Author: "Paléocéanographie (PALEOCEAN)" / Topic: 13. climate action - Searchworks@Jio Institute Digital Library Search Results

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422 results on '"Paléocéanographie (PALEOCEAN)"'

1. Impact of Indian Ocean surface temperature gradient reversals on the Indian Summer Monsoon

Author: Syee Weldeab, Carsten Rühlemann, Qinghua Ding, Vyacheslav Khon, Birgit Schneider, William R. Gray, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Geophysics, 010504 meteorology & atmospheric sciences, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 010502 geochemistry & geophysics, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: International audience
Published: 2022

2. Clumped isotopes in modern marine bivalves

Author: Damien Huyghe, Mathieu Sebilo, D. Blamart, Marc de Rafélis, Yves-Marie Paulet, Mathieu Daëron, Franck Lartaud, Centre de Géosciences (GEOSCIENCES), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'Ecogéochimie des environnements benthiques (LECOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), E2S UPPA, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Pau et des Pays de l'Adour (UPPA), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), This project was financially supported by the ANR AMOR (Data Model Reconstruction of the Cenozoic Climate). The authors thank Laurent Chauvaud and Erwan Amice (LEMAR, UBO) for the collection of A. colbecki specimens, supported by the MACARBI project (IUEM). The authors are also grateful to the captain and crew of the RV Nereis II from the UMS Service at Sea of the OOB, for their help in acquiring N. cochlear shells. Analytical facilities (a part of the PANOPLY analytical Platform) at LSCE received funding from various sources (Région Ile-de-France, Commissariat à l’Energie Atomique, Institut National des Sciences de l’Univers/Centre National de la Recherche Scientifique, Université de Versailles/St-Quentin-en-Yvelines). Thoughtful comments by Editor W. Guo, S. Petersen, N. Meckler and one anonymous reviewer helped to improve the original version of the manuscript., ANR-16-CE31-0020,AMOR,Reconstruction modèle-données des climats du Cénozoique(2016), Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Université Paris sciences et lettres (PSL), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Mollusk, 010504 meteorology & atmospheric sciences, Paleoclimate, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Mineralization (biology), Clumped isotopes, Isotopes of oxygen, chemistry.chemical_compound, Geochemistry and Petrology, Abundance (ecology), Ecosystem, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Paleo-Climat, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Abiotic component, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Isotope, Temperature, Oceanography, chemistry, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Environmental science, Carbonate, Seawater
Abstract: International audience; Oxygen-isotope measurements of fossil carbonates remain the most common method for paleoclimatic temperature reconstructions. A well-known limitation of this approach is the influence of the oxygen isotope composition of water in which mineralization occurs, which may vary significantly through space and time, and is often difficult to constrain precisely. Carbonate clumped-isotope thermometry is an alternative approach applicable to many carbonates. It is based on measurements of Δ47 (a tracer of small statistical anomalies in the abundance of rare, doubly-substituted carbonate isotopologues), and requires no independent information on the oxygen-isotope composition of parent waters. Here, we report new calibration observations of clumped isotopes in four species of calcitic marine bivalves (A. colbecki, N. cochlear, S. cucullata, M. gigas) from various ecosystems including coastal and deep-sea environments, with calcification temperatures ranging from −2 °C to 27 °C and very different amplitudes of seasonal temperature variability. At two localities with large seasonal temperature variability, calcification time intervals were constrained using a sclerochronological approach to test whether seasonal gradients of temperature can be accurately quantified based on Δ47 measurements.Our results indicate that the mature bivalves we analyzed have clumped-isotope compositions entirely consistent with earlier calibration studies processed in the I-CDES reference frame and based on biogenic/abiotic/synthetic materials. By contrast, juvenile M. gigas oysters yield substantially lower Δ47 values than expected based on their calcification environments, suggesting that their early growth phase is associated with yet poorly understood isotopic biases affecting both δ18Ο and Δ47 values. The link between seawater temperatures and bivalve Δ47 values is thus potentially applicable to seasonal reconstructions, but only if shell sections formed in cold seasons are precisely identified and precisely sampled, and taking into account that winter calcification is likely to be biased due to reduced growth rate. Moreover, the excellent agreement between our observations and the existing I-CDES calibrations further demonstrates the efficacy of the I-CDES standardization approach, and adds to the evidence that many different types of carbonates conform to statistically indistinguishable relationships between Δ47 and crystallization temperature.
Published: 2022

3. A proxy modelling approach to assess the potential of extracting ENSO signal from tropical Pacific planktonic foraminifera

Author: Didier M. Roche, Brett Metcalfe, Bryan C Lougheed, Claire Waelbroeck, Earth and Climate, Earth Sciences, Cluster Earth and Climate [Amsterdam], Department of Earth Sciences [Amsterdam], VU University Amsterdam-VU University Amsterdam, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Department of Earth Sciences [Uppsala], Uppsala University, Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), European Project: 339108,EC:FP7:ERC,ERC-2013-ADG,ACCLIMATE(2014), Vrije Universiteit Amsterdam [Amsterdam] (VU)-Vrije Universiteit Amsterdam [Amsterdam] (VU), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Vrije universiteit = Free university of Amsterdam [Amsterdam] (VU)-Vrije universiteit = Free university of Amsterdam [Amsterdam] (VU)
Subjects: 010506 paleontology, Climate Research, 010504 meteorology & atmospheric sciences, lcsh:Environmental protection, Stratigraphy, Population, 01 natural sciences, Proxy (climate), Klimatforskning, Foraminifera, lcsh:Environmental pollution, lcsh:TD169-171.8, 14. Life underwater, SDG 14 - Life Below Water, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, education, lcsh:Environmental sciences, Globigerinoides, Seabed, 0105 earth and related environmental sciences, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, education.field_of_study, biology, Paleontology, Plankton, biology.organism_classification, El Niño Southern Oscillation, Oceanography, 13. Climate action, lcsh:TD172-193.5, Environmental science, Climate model
Abstract: A complete understanding of past El Niño–Southern Oscillation (ENSO) fluctuations is important for the future predictions of regional climate using climate models. One approach to reconstructing past ENSO dynamics uses planktonic foraminifera as recorders of past climate to assess past spatio-temporal changes in upper ocean conditions. In this paper, we utilise a model of planktonic foraminifera populations, Foraminifera as Modelled Entities (FAME), to forward model the potential monthly average δ18Oc and temperature signal proxy values for Globigerinoides ruber, Globigerinoides sacculifer, and Neogloboquadrina dutertrei from input variables covering the period of the instrumental record. We test whether the modelled foraminifera population δ18Oc and Tc associated with El Niño events statistically differ from the values associated with other climate states. Provided the assumptions of the model are correct, our results indicate that the values of El Niño events can be differentiated from other climate states using these species. Our model computes the proxy values of foraminifera in the water, suggesting that, in theory, water locations for a large portion of the tropical Pacific should be suitable for differentiating El Niño events from other climate states. However, in practice it may not be possible to differentiate climate states in the sediment record. Specifically, comparison of our model results with the sedimentological features of the Pacific Ocean shows that a large portion of the hydrographically/ecologically suitable water regions coincide with low sediment accumulation rate at the sea floor and/or of sea floor that lie below threshold water depths for calcite preservation.
Published: 2020

4. Climate and the Evolution of the Ocean: The Paleoceanographic Data

Author: Natalia Vázquez Riveiros, Jean-Claude Duplessy, Elsa Cortijo, Laurent Labeyrie, Thibaut Caley, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Ramstein G., Landais A., Bouttes N., Sepulchre P., Govin A. (eds), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Gilles Ramstein, Amaëlle Landais, Nathaelle Bouttes, Pierre Sepulchre, Aline Govin, Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Water column, Oceanography, 13. Climate action, Sediment, Seawater, 14. Life underwater, Limiting, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Circumnavigation, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; The idea of reconstructing the history of oceans and climates in the past using marine sediment cores arrived quite late after the beginnings of oceanography. It was initiated in the twentieth century, well after the first attempts to measure variations in seawater temperature down the water column, which date back to the eighteenth century with the great circumnavigation expeditions. Land geologists were the first to propose paleoceanographic reconstructions from exposed marine series, limiting the collected information to former coastal waters.
Published: 2021

5. The Climate System: Its Functioning and History

Author: Jean-Claude Duplessy, Sylvie Joussaume, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Ramstein G., Landais A., Bouttes N., Sepulchre P., Govin A. (eds), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Geological evolution, business.industry, Earth science, Climate system, Biosphere, 15. Life on land, Biology, 010502 geochemistry & geophysics, 01 natural sciences, Atmosphere, 13. Climate action, Agriculture, Planet, business, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Climate plays an important role for mankind. It determines the conditions in which societies can develop as well as the resources available to them such as water and biological inputs (agriculture, forests, livestock). However, climate is a complex system. It is the result of interactions not only between the atmosphere, the oceans, landmasses and ice but also the biosphere: the living world. It varies depending on the timescale, and different mechanisms may come into play at different scales. The aim of this book is to show how a multi-disciplinary scientific community can now reconstruct, with increasing accuracy, the major features of past climates and discover how they are regulated by the geological evolution, geochemistry, physics and biology of our living planet, Earth.
Published: 2021

6. Mediterranean tephrostratigraphy and peri-Tyrrhenian explosive activity revaluated in light of the 430-365 ka record from Fucino Basin (central Italy)

Author: Monaco L.[1], Palladino D.M.[1], Gaeta M.[1], Marra F.[2], Sottili G.[1], Leicher N.[3], Mannella G.[4], Nomade S.[5], Pereira A.[6], Regattieri E.[7], Wagner B.[3], Zanchetta G.[2, 4, 12], Albert P.G.[8], Arienzo I.[9], D'Antonio M.[10], Petrosino P.[10], Manning C.J.[11], Giaccio B.[2, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Universität zu Köln = University of Cologne, University of Pisa - Università di Pisa, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), CNR Istituto di Geoscienze e Georisorse [Pisa] (IGG-CNR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Swansea University, Monaco, L., Palladino, D. M., Gaeta, M., Marra, F., Sottili, G., Leicher, N., Mannella, G., Nomade, S., Pereira, A., Regattieri, E., Wagner, B., Zanchetta, G., Albert, P. G., Arienzo, I., D'Antonio, M., Petrosino, P., Manning, C. J., and Giaccio, B.
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Pyroclastic rock, Peri-Tyrrhenian explosive volcanism, Volcanism, 010502 geochemistry & geophysics, 01 natural sciences, Marine Isotope Stage 11, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Mediterranean tephrochronology, Tephra, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, Vulcanian eruption, geography.geographical_feature_category, Volcano, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, General Earth and Planetary Sciences, Sedimentary rock, Geology, Volcanic ash
Abstract: International audience; Accurately reconstructing the scale and timing of dynamic processes, such as Middle-Late Pleistocene explosive volcanism and rapid climatic changes, requires rigorous and independent chronological constraints. In this framework, the study of distal volcanic ash layers, or tephra, transported and deposited over wide regions during explosive volcanic eruptions, is increasingly being recognised as a fundamental chronostratigraphic tool for addressing these challenging issues. Here we present a high-resolution distal tephra record preserved in the lacustrine sedimentary succession of the Fucino Basin, central Italy. The investigated record spans the 430-365 ka time interval, covering the entirety of Marine Isotope Stage 11 (MIS 11), and provides important insights into peri-Tyrrhenian potassic explosive volcanism from sources located in central Italy against a backdrop of Mediterranean palaeooclimate records. The succession of ash fall events of this time interval is reconstructed through a detailed lithostratigraphic, geochemical and 40Ar/39Ar geochronological characterization of the deposits preserved as discrete layers in the Fucino F4-F5 sediment core. This work is complemented by similarly detailed characterization of selected proximal pyroclastic units from the peri-Tyrrhenian potassic volcanoes. Geochemical fingerprinting of the tephra deposits by means of their major, minor and trace elements and Sr isotope composition indicates that all the thirty-two investigated ash layers derived from the peri-Tyrrhenian potassic volcanoes. The stratigraphically continuous succession of the Fucino tephra layers allowed the development of a fully independent, 40Ar/39Ar age-constrained, Bayesian age-depth model for the investigated time interval. The age-model allows us to establish modelled ages for the tephra layers within the succession that are not directly dated. The resulting dated tephra record clearly reveals a highly time resolved and previously unparalelled chronicle of explosive activity from the Vulsini, Vico, Sabatini, Colli Albani and Roccamonfina volcanic complexes. Our study provides a benchmark and valuable geochemical and geochronological dataset to be used as a reference for any future development and application of the tephrostratigraphic methods across the central Mediterranean area both during the investigated 430-365 ka time interval, and deeper in time. This contribution underlines the importance of integrating proximal and distal sedimentary records to more accurately establish long-term and comprehensive volcanic eruption records.
Published: 2021

7. Exploring the links between volcano flank collapse and the magmatic evolution of an ocean island volcano: Fogo, Cape Verde

Author: Patrick Bachèlery, Régis Doucelance, Abdelmouhcine Gannoun, Delphine Auclair, Chantal Bosq, Mhammed Benbakkar, Raphaël Paris, Hervé Guillou, Melodie-Neige Cornu, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Incompatible element, 010504 meteorology & atmospheric sciences, Science, Volcanology, 010502 geochemistry & geophysics, 01 natural sciences, Article, Cape verde, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Petrology, 0105 earth and related environmental sciences, geography, Multidisciplinary, geography.geographical_feature_category, Partial melting, Natural hazards, Geochemistry, Volcano, 13. Climate action, Magma, Medicine, Igneous differentiation, Geology
Abstract: Mass-wasting of ocean island volcanoes is a well-documented phenomenon. Massive flank collapses may imply tens to hundreds of km3 and generate mega-tsunamis. However, the causal links between this large-scale, low-frequency instability, and the time–space evolution of magma storage, crystal fractionation/accumulation, lithospheric assimilation, and partial melting remains unclear. This paper aims at tracking time variations and links between lithospheric, crustal and surface processes before and after a major flank collapse (Monte Amarelo collapse ca. 70 ka) of Fogo volcano, Cape Verde Islands, by analysing the chemical composition (major, trace elements, and Sr–Nd–Pb isotopes) and age-controlled stratigraphy (K–Ar and Ar–Ar dating) of lavas along vertical sections (Bordeira caldera walls). The high-resolution sampling allows detecting original variations of composition at different time-scales: (1) a 60 kyrs-long period of increase of magma differentiation before the collapse; (2) a 10 kyrs-long episode of reorganization of magma storage and evacuation of residual magmas (enriched in incompatible elements) after the collapse; and (3) a delayed impact at the lithospheric scale ~ 50 kyrs after the collapse (increasing EM1-like materiel assimilation).
Published: 2021

8. Clumped isotope evidence for Early Jurassic extreme polar warmth and high climate sensitivity

Author: Bruno Reynard, Oleg Lutikov, Guillaume Suan, Mathieu Daëron, Christophe Lécuyer, Mikhail A. Rogov, Gilles Montagnac, Thomas Letulle, Arnauld Vinçon-Laugier, Ján Schlögl, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Geological Institute of the Russian Academy of Sciences, Russian Academy of Sciences [Moscow] (RAS), Comenius University in Bratislava, and ANR-18-CE31-0020,Oxymore,Rapports isotopiques de l'oxygène des océans mésozoïques revisités(2018)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Stratigraphy, Paleontology, Atmospheric sciences, Isotopes of oxygen, TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, Arctic, 13. Climate action, Polar, Climate sensitivity, Seawater, Climate model, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Paleogene, Geology, Holocene
Abstract: Periods of high atmospheric CO2 levels during the Cretaceous–early Paleogene (∼ 140 to 34 Myr ago) were marked by very high polar temperatures and reduced latitudinal gradients relative to the Holocene. These features represent a challenge for most climate models, implying either higher-than-predicted climate sensitivity to atmospheric CO2 or systematic biases or misinterpretations in proxy data. Here, we present a reconstruction of marine temperatures at polar (> 80∘) and middle (∼ 40∘) paleolatitudes during the Early Jurassic (∼ 180 Myr ago) based on the clumped isotope (Δ47) and oxygen isotope (δ18Oc) analyses of shallow buried pristine mollusc shells. Reconstructed calcification temperatures range from ∼ 8 to ∼ 18 ∘C in the Toarcian Arctic and from ∼ 24 to ∼ 28 ∘C in Pliensbachian mid-paleolatitudes. These polar temperatures were ∼ 10–20 ∘C higher than present along with reduced latitudinal gradients. Reconstructed seawater oxygen isotope values (δ18Ow) of −1.5 ‰ to 0.5 ‰ VSMOW and of −5 ‰ to −2.5 ‰ VSMOW at middle and polar paleolatitudes, respectively, point to a significant freshwater contribution in Arctic regions. These data highlight the risk of assuming the same δ18Osw value for δ18O-derived temperature from different oceanic regions. These findings provide critical new constraints for model simulations of Jurassic temperatures and δ18Osw values and suggest that high climate sensitivity has been a hallmark of greenhouse climates for at least 180 Myr.
Published: 2021

9. Post–glacial tephrochronology record off the Chilean continental margin (∼41° S)

Author: Julius Nouet, Elisabeth Michel, Guillaume Delpech, Consuelo Martínez Fontaine, Gustavo Villarosa, Fatima Manssouri, Giuseppe Siani, Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010506 paleontology, Archeology, Volcanic hazards, 010504 meteorology & atmospheric sciences, Sedimentology-marine cores, Post–glacial, 01 natural sciences, Quaternary, Paleontology, Continental margin, Deglaciation, Glacial period, Tephra, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Major and trace elements, Geology, South America, Post-glacial, Radiocarbon, Volcano, 13. Climate action, Southern volcanic zone, Tephrochronology
Abstract: International audience; The Southern Volcanic Zone of the Andes (∼33–46° S) is a very active volcanic zone with several volcanic centers recording recurrent historical activity (e.g. Llaima, Villarrica, Puyehue-Cordón Caulle, Osorno, Calbuco and Hudson). Tephrochronology is a valuable tool to help better understand the eruptive history of volcanic centers, essential for producing volcanic hazard maps. Additionally, tephrochronology can also be very useful to synchronize stratigraphic records of different nature such as paleoclimatological, paleoceanographical and archaeological records on land, lakes, ice and the ocean. Here we present a (crypto) tephrochronological record from two marine sediment cores retrieved in the Chilean continental margin at ∼41° S and ∼41.6° S. The records display continuous sedimentation since the late glacial, as robustly constrained by planktonic foraminifera δ18O and 14C dates. During this period, twenty three cryptotephras were identified as glass shard peaks together with two ∼25–30 cm–thick visible tephras (one in each core). The source of the (crypto) tephras was mainly constrained by major and trace element geochemistry of individual glass shards together with their stratigraphic position, since it is not possible to observe physical characteristics, such as color and grain size, when analyzing cryptotephras. From these, one cryptotephra was robustly correlated with the HW7 eruption from the Hudson volcano occurring in the Late Holocene at ∼1.5 cal ka BP; and the two visible tephra layers were identified as distant correlatives of the Lepué tephra originating from Michinmahuida volcano and occurring in the Deglaciation/Holocene transition at around 11 cal ka BP. Additionally, eight cryptotephra occurring at ∼3.6, 6.2, 7.0, 8.5, 9.6, 14.2, 15.9 and 18.2 cal ka BP were robustly identified as sourced from Michinmahuida volcano but where otherwise not correlated, providing novel evidence of pre Holocene activity of this volcanic center.
Published: 2021

10. Mediterranean faunal evolution and biochronological events during the last 24 kyr

Author: Nadine Tisnérat-Laborde, Nejib Kallel, François Thil, Sonda Zouari, Abdelaziz Kallel, Soumaya Boussetta, Elisabeth Michel, Giuseppe Siani, Université de Sfax - University of Sfax, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Mediterranean climate, 010506 paleontology, Planktonic foraminifera, 010504 meteorology & atmospheric sciences, Climate change, Biozone, Structural basin, Oceanography, 01 natural sciences, AMS(14)C, Foraminifera, Mediterranean sea, Mediterranean Sea, 14. Life underwater, Bio-event, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, biology, Paleontology, biology.organism_classification, LGM, SST, 13. Climate action, Period (geology), Geology, Chronology
Abstract: We generated high-resolution biochronological records in the Mediterranean Sea covering the period extending to the Late-glacial. The present study is based on micropaleontological, sea-surface temperature (SST) and oxygen isotopic analyses performed along three well-dated deep-sea cores: REC1353, KET80–19 and MD84–641 recovered in the Siculo-Tunisian Strait, Tyrrhenian Sea and Levantine Basin, respectively. The quantitative distributional patterns of planktic foraminifera permitted to identify seven biozones based on the apparition and/or disappearance of the main specific taxa or by their noticeable abundance peaks. Abundance records display that major changes in planktic foraminiferal assemblages have a similar pattern mainly in central and western basins. In particular, four recognized bio-events can be used to establish or to improve the chronology of Mediterranean deep-sea cores. The comparison of the SST estimates and foraminiferal records with those of NGRIP ice-core shows a similarity between the Greenland climate and the Mediterranean hydrology. This indicates that the main climate changes recorded in the North Atlantic are globally in phase with those observed in the Mediterranean region.
Published: 2021

11. Antarctic Polar Front migrations in the Kerguelen Plateau region, Southern Ocean, over the past 360 kyrs

Author: Elisabeth Michel, Xavier Crosta, Takuya Itaki, Minoru Ikehara, Giuseppe Cortese, Olivier Ther, M. Civel-Mazens, Alain Mazaud, Kochi University, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Climat et Magnétisme (CLIMAG), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: 010504 meteorology & atmospheric sciences, 02 engineering and technology, Oceanography, 01 natural sciences, Kerguelen, Latitude, Water column, Fronts, 0202 electrical engineering, electronic engineering, information engineering, 14. Life underwater, Glacial period, Southern Ocean, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Trough (meteorology), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Polar front, Diatoms, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, Plateau, geography.geographical_feature_category, Ocean current, 020206 networking & telecommunications, Radiolarians, 13. Climate action, Interglacial, Geology
Abstract: In the Southern Ocean (SO), climate-driven latitudinal migrations of the Antarctic Circumpolar Current (ACC) frontal system impact large-scale ocean circulation and primary productivity. Latitudinal migrations may not have been identical in all SO basins due to the presence or absence of regional bathymetric obstacles. The Antarctic Polar Front (APF), defined by the 3–5 °C surface temperature range and the 2 °C subsurface temperature minimum at 200 m, is particularly important for nutrient redistribution and biodiversity, influencing the soft tissue carbon pump in the modern SO. However, previous assessments of its migrations in the past, mostly based on a single metric or indirect observations, were not always robust. Here, we combine a new proxy for subsurface temperature (sub-ST) reconstructions based on radiolarian assemblages (sub-STrad), with relative abundance variations of key radiolarian species, and sea-surface temperatures (SST) reconstructions, based on diatom assemblages (SSTdiat), to refine estimations of the past mean APF locations in the Kerguelen Plateau (KP) region. Data from three sediment cores on a south (55°S) to north (47°S) transect are used to trace the mean APF locations for three climate states, glacials, peak-interglacials and mild-interglacials. Our results suggest that the APF, presently located south of Kerguelen Islands, shifted by 6–7 degrees of latitude and was located north of the KP during all glacial periods of the last 360 kyrs. This suggests that the ACC major flow interacted less with the bottom topography relative to its modern counterpart, probably resulting in less mixing of the water column over and in the lee of the KP. We propose that this process participated in the isolation of Antarctic surface waters (AASW) and in the reduction of macro-nutrient supply, thus resulting in lower regional productivity. During the warmer-than-present early interglacial periods, the APF probably migrated south by ~5 degrees of latitude relative to its modern position, to pass through the Fawn Trough. Contrary to glacial periods, the APF was forced in an “S” shape while the ACC main flow was constrained against the northern tip of the KP. In this configuration, a stronger interaction between the ACC, its associated fronts, and topography is expected, resulting in more mixing of the water column over and east of the KP. Congruently, siliceous productivity was probably restrained to latitudes south of the Fawn Trough.
Published: 2021

12. Disentangling magnetic and environmental signatures of sedimentary 10Be/9Be records

Author: Didier Bourlès, Quentin Simon, Tatiana Savranskaia, Ramon Egli, Nicolas Thouveny, Franck Bassinot, Laure Meynadier, Jean-Pierre Valet, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Central Institute for Meteorology and Geodynamics [Vienna] (ZAMG), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), European Research Council (ERC)European Commission339899INSU/CNRS, IRDFrench National Research Agency (ANR), ANR-10-EQPX-0024,ASTER-CEREGE,PLATEFORME DE GEOCHIMIE ISOTOPIQUE ASTER/CEREGE(2010), European Project: 246937,EC:FP7:PEOPLE,FP7-PEOPLE-2009-IRSES,SIMTECH(2010), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Atmospheric sciences, 01 natural sciences, Authigenic Be-10/Be-9 ratio, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Cosmogenic nuclides, Cosmogenic nuclide, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Geomagnetic field intensity, 0105 earth and related environmental sciences, Global and Planetary Change, Terrigenous sediment, Sediment, Geology, Authigenic, Moment (mathematics), Dipole, Amplitude, Earth's magnetic field, 13. Climate action, Beryllium, Matuyama-brunhes reversal
Abstract: Reconstructions of the global production rate of the cosmogenic isotope 10Be from sedimentary records of authigenic 10Be/9Be ratios have been successfully used to obtain independent estimates of geomagnetic dipole moment variations caused by field excursions or reversals. In this study, we assess the reliability of 10Be/9Be as a proxy for the cosmogenic 10Be production rate by evaluating two potential biasing sources represented by sediment composition and climatic modulation. For this purpose, we compare five high-resolution 10Be/9Be records of the Matuyama-Brunhes (M-B) field reversal from sediment cores of the Indian, West Pacific, and North Atlantic oceans. Significant increase of 10Be/9Be ratios at ∼ 774 ka is explained in terms of the dominant control of geomagnetic modulation during the M-B reversal. Results do not support the existence of a direct proportionality between measured sedimentary 10Be/9Be ratio and cosmogenic 10Be production rate, as shown by 10Be/9Be records that offset relative to each other during and outside the M-B reversal. Residual differences between offset-corrected rescaled records do not appear to be related to an incomplete correction of variable sediment scavenging efficiencies by 9Be normalization. Instead, these differences can be explained by a common climatic modulation model, assuming a linear relation between 10Be/9Be and the global 10Be production rate with site- and time-dependent additive and multiplicative coefficients. These coefficients are linear functions of a single global climate proxy identified with the benthic δ 18 O record. Additive coefficients are almost constant in time and can represent up to ∼ 60% of the average 10Be/9Be value during periods of stable field polarity. Multiplicative coefficients are also site-specific, with mean values representing the bulk scavenging efficiency of the site, and variations about this mean expressing a multiplicative climatic modulation of the 10Be production rate. The amplitude of this modulation amounts to 10–15% of the maximum variations recorded during the M-B reversal and is sufficiently large to mask minor variations of the dipole moment during stable polarity periods. Reconstructions of the geomagnetic dipole intensity can benefit from the information about climatic modulation effects gained with our modelling approach. Best suited sites for magnetic field reconstructions should be characterized by minimal Be-recycling contributions from ancient 10Be reservoirs and minimal climatic modulation, as far as it can be determined from relative comparisons with other records. These conditions are most likely encountered in open basins at sites (1) with 2.8 km water depth, (2) > 200 km offshore, and (3) located underneath a large current system extending over regions with minimum terrigenous inputs. Scaling all records with respect to a chosen reference enables to produce 10Be/9Be stacks with reduced noise and short-term local environmental effects. Differences between stacks obtained in this manner highlight global climatic effects that need to be considered when generating calibrated reconstructions of the geomagnetic dipole moment.
Published: 2021

13. Multi-tracer study of continental erosion and sediment transport to the Red Sea and the Gulf of Aden during the last 20 ka

Author: Franck Bassinot, Laure Meynadier, Virginia Rojas, Serge Miska, Jean-Pierre Valet, Christophe Colin, Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Gulf of Aden, African Humid Period, 010506 paleontology, Archeology, radiogenic isotopes, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, siliciclastic grain-size, Monsoon, 01 natural sciences, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Deglaciation, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, clay mineralogy, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Monsoon of South Asia, Global and Planetary Change, geography, geography.geographical_feature_category, Last Glacial Period, Sediment, Geology, 15. Life on land, Red Sea, Volcanic rock, Oceanography, [SDU]Sciences of the Universe [physics], 13. Climate action, Aridification, Sedimentary rock, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; Mineralogical compositions and grain-size distributions combined with 87Sr/86Sr and εNd values of the detrital fraction were studied on cores recovered from the Gulf of Aden (MD92-1002) and the Red Sea (MD92-1008) basins in order to document past changes in Indian monsoon and northwesterly winds during the last glacial-interglacial transition (the last 20 ka), encompassing the African Humid Period (AHP). The εNd vs. 87Sr/86Sr plot indicates that sediments result from the mixing of two main sedimentary sources corresponding to the Afar volcanic rocks in Ethiopia and to the Arabian-Nubian Shield. Variations of sediment isotopic and mineralogical composition point to a diminution of the volcanic source contribution during the last deglaciation. Changes of mineral-accumulation rates and grain-size distributions denote a decline in the aridity of the source regions during the Holocene, particularly of the Afar volcanic region. In this area, the reduction of detrital supply, from 15 cal ka BP, can be explained by an increase of precipitations during the AHP, which resulted in an expansion of the vegetation cover and lake extensions in East Africa. In the Arabian Peninsula, precipitations were confined to the south, allowing sediments to be transported even during the Holocene. Our data suggest that the southwest monsoon was not the main carrier of aeolian sediments to the Red Sea and Gulf of Aden basins, but the Northwesterlies. In the Red Sea, the isotopic and mineralogical tracers reveal a contribution from Saharan dust between 16 and 12 cal ka BP, transported from the Nile catchment after aridification during Heinrich event 1.
Published: 2019

14. Nonthermal Influences on Mg/Ca in Planktonic Foraminifera: A Review of Culture Studies and Application to the Last Glacial Maximum

Author: William R Gray, David Evans, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of St Andrews [Scotland], Goethe-University Frankfurt am Main, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, biology, Chemistry, Paleontology, Last Glacial Maximum, Globigerina bulloides, 010502 geochemistry & geophysics, Oceanography, biology.organism_classification, 01 natural sciences, Salinity, Foraminifera, chemistry.chemical_compound, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Environmental chemistry, Deglaciation, Carbonate, Seawater, 14. Life underwater, Globigerinoides, 0105 earth and related environmental sciences
Abstract: International audience; Planktonic foraminiferal Mg/Ca is one of the most widely applied sea surface temperature proxies. While the influence of salinity on Mg/Ca has led the accuracy of Mg/Ca-temperatures to be questioned, the effect of seawater carbonate chemistry (pH) is seldom accounted for down-core. Using published data sets, we review controls on Mg/Ca in laboratory cultures of planktonic foraminifera Globigerinoides ruber (white), Trilobatus sacculifer, Globigerina bulloides, and Orbulina universa. All are characterized by a temperature sensitivity of~6% per°C and a salinity sensitivity of~4% per salinity unit; all except T. sacculifer are sensitive to carbonate chemistry (−5 to −9% per 0.1 pH units). We demonstrate the down-core manifestation of these sensitivities using data spanning the last deglaciation and an Earth System Model forced with last glacial maximum conditions. While the effects of salinity are relatively minor, seawater carbonate chemistry exerts a large bias on Mg/Ca temperature if unaccounted for; however, as local pH changes beyond the effect of atmospheric CO 2 are relatively small across most of the ocean (less than ±0.05 pH units, 2σ), atmospheric CO 2 can be used to accurately correct Mg/Ca temperatures. We present protocols to correct Mg/Ca for pH down-core using either atmospheric CO 2 or (preferably) boron isotopes in a new software package "MgCaRB.
Published: 2019

15. Spatial variability of Quaternary denudation rates across a volcanic ocean island (Santo Antão, Cape Verde) from cosmogenic 3 He

Author: Raphaël Pik, Camille Litty, Pierre-Henri Blard, Julien Charreau, Sébastien Nomade, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and TelluS Program of CNRS/INSU, France
Subjects: Basalt, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Structural basin, 010502 geochemistry & geophysics, Spatial distribution, 01 natural sciences, Cape verde, Denudation, Volcano, 13. Climate action, Spatial variability, Physical geography, Quaternary, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: International audience; Denudation of volcanic ocean islands creates remarkable landscapes and contributes to Earth's carbon cycle, since the chemical alteration of basalts is a CO2 sink. Because many volcanic islands have large climate gradients and relatively low variations in lithology and tectonic history, they represent excellent natural laboratories for studying climatic effects on landscape evolution. However, little is known about the control of denudation rates in ocean islands and the respective influences of climatic gradients and morphological parameters. Here, we present new measurements of long-term denudation rates from Santo Antão Island, Cape Verde (17°N). In this 779 km 2 island, mean annual precipitation ranges from 40 mm.yr-1 in the southwest to 1100 mm.yr-1 in the north. To constrain the spatial distribution of denudation rates, we measured the cosmogenic 3 He concentration in river-transported pyroxene grains from 23 river bedload samples. We obtained basin wide denudation rates ranging from 2.7 ± 0.1 to 57.5 ± 0.3 m/Ma. The denudation rates display a significant spatial variability, with the highest rates in catchments located in the northeast side of the island where modern precipitation are the highest and low denudation rates in the southern and western dry basins. Our study shows that precipitation is the main control on denudation and landscape development of the Santo Antão volcanic island. This study provides for the first time the spatial distribution of denudation rates across a volcanic island located in a tropical zone.
Published: 2021

16. InterCarb: A community effort to improve inter-laboratory standardization of the carbonate clumped isotope thermometer using carbonate standards

Author: A. Piasecki, John M. Eiler, Stefano M. Bernasconi, Ilja Kocken, Matthieu Clog, Kristin D. Bergmann, Sierra V. Petersen, Julia R. Kelson, Damien Calmels, M. Hermoso, Jamie Lucarelli, Elise M. Pelletier, Deepshikha Upadhyay, D. Liang, Landon Burgener, N. Meinicke, Ben Elliott, Thomas Jan Leutert, Inigo A. Müller, Ethan G. Hyland, Sean T. Murray, D. Blamart, Miquela Ingalls, Cédric M. John, Andrew J. Schauer, F. Dux, M. Bonifacie, Carine Chaduteau, A. Neary, Peter K. Swart, B. H. Passey, Ian Z. Winkelstern, Anne C. Fetrow, Xavier Mangenot, A. B. Jost, Eugeni Barkan, Aradhna Tripati, N. Packard, Madalina Jaggi, Martin Ziegler, Kathryn E. Snell, Emily J. Beverly, S. L. Goldberg, Naohiro Yoshida, Hagit P. Affek, Naizhong Zhang, D. Yarian, K. W. Huntington, David Bajnai, Jens Fiebig, Tobias Kluge, Amzad H. Laskar, Tyler J. Mackey, Mathieu Daëron, Brett Davidheiser-Kroll, Noah Anderson, S. E. Modestou, Anna Nele Meckler, Torsten Vennemann, Amelia J. Davies, S. A. Katz, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Université du Littoral Côte d'Opale (ULCO), 1156134, 1713275, 1933130, 206021‐164032 National Science Foundation, NSF: 1925973 David and Lucile Packard Foundation, DLPF National Aeronautics and Space Administration, NASA: 80NSSC19K0464 Basic Energy Sciences, BES: DE‐FG02‐13ER16402 University of Michigan, U-M: 1854873, 724097 University of Colorado Boulder: 1524785 North Carolina State University, NCSU Horizon 2020 Framework Programme, H2020: 638467 Trond Mohn stiftelse European Research Council, ERC Japan Society for the Promotion of Science, KAKEN: JP17H06105 Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF: 200020_160046, 200021_143485 Eidgenössische Technische Hochschule Zürich, ETH Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO: 016.161.365 Israel Science Foundation, ISF: 1000/16, 171/16, DE‐SC0016561 Institut national des sciences de l'Univers, INSU,CNRS Centre National de la Recherche Scientifique, CNRS Qatar Science and Technology Park, QSTP Institut de Physique du Globe de Paris, IPGP, S. M. Bernasconi acknowledges instrumentation funding from ETH Zürich and support from Swiss National Science Foundation grants 200021_143485, 200020_160046. M. Daëron acknowledges the clumped‐isotope facility at LSCE is part of PANOPLY (Plateforme Analytique Géosciences Paris‐Saclay) and was supported by the following institutions: Région Ile‐de‐France, Direction des Sciences de la Matière du Commissariat à l’Energie Atomique, Institut National des Sciences de l’Univers, Centre National de la Recherche Scientifique, Universtité de Versailles/Saint‐Quentin‐en‐Yvelines. K. D. Bergmann and the MIT carbonate clumped isotope facility acknowledge support from the Packard Foundation, the Agouron Foundation and NASA Exobiology Grant 80NSSC19K0464. M. Bonifacie acknowledges the program Emergences Ville de Paris for early funding that allowed building her clumped isotope laboratory at Institut de Physique du Globe de Paris. M. Bonifacie also thanks IPGP and Université de Paris for support for the organization of the VIth Clumped Isotope Workshop in Paris in 2017. Funding was provided to C. M. John and the Imperial College Clumped Isotope Laboratory by Qatar Petroleum, Shell, and the Qatar Science and Technology Panel. Funding was provided to K. W. Huntington at University of Washington from NSF EAR grants 1933130, 1713275, and 1156134. T. Vennemann acknowledges the support of the Swiss National Science Foundation grant 206021‐164032. A. N. Meckler acknowledges funding from the Trond Mohn Foundation and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 638467). Funding was provided to the Tripati Laboratory at UCLA for these analyses from DOE BES grant DE‐FG02‐13ER16402. Funding was provided to the Hyland Laboratory at NCSU for these analyses from NSF EAR‐FRES grant 1925973. Funding was provided to the Yoshida Laboratory at Tokyo Tech. for these analyses from JSPS grant JP17H06105. Funding was provided to the CLIMB Lab at the University of Bergen for these analyses by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 638467) and by the Trond Mohn Foundation. Funding was provided to the UU Clumped Laboratory at Utrecht University by the Netherlands Research Organization (NWO) through VIDI grant 016.161.365. Funding was provided to the CUBES‐SIL at CU Boulder by startup funds from the University of Colorado Boulder and NSF EAR grant 1524785. The UM SCIPP Laboratory was supported by startup funds from the University of Michigan. J. R. Kelson was supported by NSF PRF grant 1854873. HPA acknowledges support by ERC (Grant no.724097) and ISF (Grant no. 171/16 and 1000/16). Funding was provided to the Eiler lab at Caltech from the DOE BES program, award number DE‐SC0016561., European Project: 638467,H2020,ERC-2014-STG,C4T(2015), European Project: 0724097(2007), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Geochemistry & Geophysics, Stable Isotope Geochemistry, 010504 meteorology & atmospheric sciences, Standardization, Geography & travel, Mineralogy, carbonate, clumped isotopes, interlaboratory calibration, mass spectrometry, reference materials, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, interlaboratory calibration, Biogeosciences, 010502 geochemistry & geophysics, 01 natural sciences, Oceanography: Biological and Chemical, chemistry.chemical_compound, carbonate, Clumped Isotope Geochemistry: From Theory to Applications, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Data Analysis: Algorithms and Implementation, Instruments and Techniques, Nuclear Experiment, ddc:910, 0105 earth and related environmental sciences, mass spectrometry, Isotopic Composition and Chemistry, Isotope, Stable Isotopes, 010401 analytical chemistry, clumped isotopes, reference materials, 0104 chemical sciences, Geochemistry, Geophysics, chemistry, 13. Climate action, Thermometer, Physical Sciences, Earth Sciences, Carbonate, Computational Geophysics, Geology, Research Article
Abstract: Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth‐system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ47) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ47 and Δ47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ47 (I‐CDES) values for Intercarb‐Carbon Dioxide Equilibrium Scale., Key Points The exclusive use of carbonate reference materials is a robust method for the standardization of clumped isotope measurementsMeasurements using different acid temperatures, designs of preparation lines, and mass spectrometers are statistically indistinguishableWe propose new consensus values for a set of seven carbonate reference materials and updated guidelines to report clumped isotope measurements
Published: 2021

17. Paleoproductivity modes in central Mediterranean during MIS 20 ‐ MIS 18: Calcareous plankton and alkenone variability

Author: Franck Bassinot, Maria Marino, Neri Ciaranfi, Timothy D Herbert, Adele Bertini, Patrizia Maiorano, Angela Girone, Sébastien Nomade, Pietro Bazzicalupo, University of Bari Aldo Moro (UNIBA), Brown University, Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro (UNIBA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Università degli Studi di Firenze = University of Florence (UniFI)
Subjects: Mediterranean climate, Marine isotope stage, 010506 paleontology, Atmospheric Science, Alkenone, 010504 meteorology & atmospheric sciences, Paleontology, 15. Life on land, Oceanography, 01 natural sciences, Productivity (ecology), 13. Climate action, Interglacial, Environmental science, 14. Life underwater, Stadial, Glacial period, Surface water, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: International audience; Paleoproductivity is reconstructed across a Mediterranean benchmark record, the Early/Middle Pleistocene Montalbano Jonico section, cropping out in southern Italy. High-resolution coccolithophore and alkenone data (C37 and C37:2/C38:2 ratio) were collected in order to extend the data set on Mediterranean paleoproductivity pattern and forcing mechanisms. The multi-proxy record indicates low productivity during glacial and stadial phases and enhanced productivity during interglacial and interstadials. Increased surface water turbidity, cold-water temperature and polar-subpolar low salinity water incursion appear as the dominant controls for low productivity during Marine Isotope Stage (MIS) 20. Enhanced productivity during MIS 19c was sustained by warmer surface waters, coupled with a seasonal precipitation regime, providing higher nutrient availability. Productivity increases during interstadials with respect to stadials, in relation with enhanced land-derived nutrient input through river discharge during wetter winters. The productivity scenario we propose is similar to those reconstructed from deep-sea records in the central and western Mediterranean during Dansgaard-Oeschger oscillations over the last 70 ka. This indicates that similar forcing mechanisms acted on productivity dynamics on a regional scale over different times. We suggest that migration of the westerly wind system over the Mediterranean and the polar water inflow influenced productivity on a regional scale. The acquired data set provides new evidences on the environmental significance of the C37:2/C38:2 ratio and on its relation with surface water productivity.
Published: 2021

18. A Unified Clumped Isotope Thermometer Calibration (0.5–1,100°C) Using Carbonate‐Based Standardization

Author: J Horita, K. W. Huntington, Sándor Kele, Mathieu Daëron, Tyler J. Mackey, Cédric M. John, M. Bonifacie, Stefano M. Bernasconi, A. B. Jost, Kristin D. Bergmann, Tobias Kluge, Julia R. Kelson, P Petschnig, Noah Anderson, Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Calcite, 010504 meteorology & atmospheric sciences, Dolomite, Carbonate minerals, Mineralogy, 010502 geochemistry & geophysics, 01 natural sciences, Temperature measurement, Isotopes of oxygen, chemistry.chemical_compound, Paleothermometer, Geophysics, chemistry, 13. Climate action, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Calibration, General Earth and Planetary Sciences, Environmental science, Carbonate, 0105 earth and related environmental sciences, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; The potential for carbonate clumped isotope thermometry to independently constrain both the formation temperature of carbonate minerals and fluid oxygen isotope composition allows insight into long-standing questions in the Earth sciences, but remaining discrepancies between calibration schemes hamper interpretation of temperature measurements. To address discrepancies between calibrations, we designed and analyzed a sample suite (41 total samples) with broad applicability across the geosciences, with an exceptionally wide range of formation temperatures, precipitation methods, and mineralogies. We see no statistically significant offset between sample types, although the comparison of calcite and dolomite remains inconclusive. When data are reduced identically, the regression defined by this study is nearly identical to that defined by four previous calibration studies that used carbonate-based standardization; we combine these data to present a composite carbonate-standardized regression equation. Agreement across a wide range of temperature and sample types demonstrates a unified, broadly applicable clumped isotope thermometer calibration.
Published: 2021

19. Modern relationships between microscopic charcoal in marine sediments and fire regimes on adjacent landmasses to refine the interpretation of marine paleofire records: an Iberian case study

Author: Florent Mouillot, Polychronis C Tzedakis, Filipa Naughton, Maria Fernanda Sánchez-Goñi, Anne-Laure Daniau, Muriel Georget, Pierre Anschutz, Thierry Mulder, David A. Hodell, Fatima F Abrantes, Bernard Dennielou, Marion Genet, Vincent Hanquiez, Jérôme Bonnin, Valérie David, Linda Rossignol, Franck Bassinot, Sabine Schmidt, Frédérique Eynaud, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ANR BRAISEFrench INSU (Institut National des Sciences de l'Univers) programme LEFE (Les Enveloppes Fluides et l’Environnement) CAMPFIRE projectESA FIRECCI, ANR-19-CE01-0001,BRAISE,Reconstruction des surfaces brulées à partir des particules de microcharbon préservées dans le sédiment marin(2019), and EPOC - CNRS, UMR 5805
Subjects: Mediterranean climate, Archeology, 010504 meteorology & atmospheric sciences, Microcharcoal, Climate, Marine surface sediments, 010502 geochemistry & geophysics, 01 natural sciences, Iberian peninsula, Western europe, River mouth, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Vegetation, Fire regime, Sediment, Geology, 15. Life on land, 13. Climate action, [SDU]Sciences of the Universe [physics], Interglacial, Calibration, Physical geography
Abstract: Marine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies of the current fire-microcharcoal relationship. Here, we present the analysis of microcharcoal concentration and morphology in 102 core-top sediment samples collected in the Iberian margin and the Gulf of Cadiz. We show that microcharcoal concentrations are influenced by the water depth or the distance from the river mouth. At regional scale, the mean microcharcoal concentrations and microcharcoal elongation (length to width ratio) show a marked latitudinal variation in their distribution, primarily controlled by the type of burnt vegetation in the adjacent continent. High microcharcoal concentrations in marine sediments represent rare, large and intense fires in open Mediterranean woodlands. Based on these results, the increasing trend of microcharcoal concentrations recorded since 8 ka in the well-known marine sedimentary core MD95-2042 off the Iberian margin indicates the occurrence of large and infrequent fires of high intensity due to the progressive degradation of the Mediterranean forest and the expansion of shrublands. info:eu-repo/semantics/publishedVersion
Published: 2021

20. Calibration of the dual clumped isotope thermometer for carbonates

Author: Gaby Schneider, Miguel Bernecker, Jens Fiebig, Mathieu Daëron, Weifu Guo, Stefano M. Bernasconi, Ronny Boch, Martin Dietzel, Josué J. Jautzy, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Calcite, Materials science, 010504 meteorology & atmospheric sciences, Isotope, Analytical chemistry, Atmospheric temperature range, 010502 geochemistry & geophysics, 01 natural sciences, Mineralization (biology), Dual (category theory), chemistry.chemical_compound, chemistry, Geochemistry and Petrology, 13. Climate action, Thermometer, Carbon dioxide, Dissolved organic carbon, Calibration, Carbonate, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, Isotope analysis
Abstract: The Δ47 (paleo)thermometer has opened a new avenue to determine carbonate formation temperatures independent of the oxygen isotopic composition of the fluid from which the carbonate crystallized. A major limitation of this thermometer is related to kinetic effects if homogeneous isotopic equilibrium is not attained during carbonate precipitation. Dual clumped isotope thermometry – the high-precision analysis of Δ48 along with Δ47 in CO2 evolved from phosphoric acid digestion of carbonates – makes it possible to resolve temperature from the kinetic information recorded in an individual carbonate phase. Therefore, it provides a new opportunity to identify (bio)mineralization pathways and to determine carbonate formation temperatures devoid of a kinetic bias, based solely on isotopic analysis of a single carbonate phase. Identification of the nature and extent of kinetic effects as well as the reconstruction of accurate formation temperatures requires knowledge of the position of equilibrium in Δ47 vs Δ48 space. Here, we present Δ47 and Δ48 data of carbonates that were previously considered as having crystallized closest to equilibrium in a temperature range of 8 to 1100 °C. Across this range, the temperature dependences of Δ47 and Δ48 are best expressed by the following fourth order polynomials of 1/T: Δ47 (CDES 90) (‰) = 1.038 (−5.897 1/T − 3.521 103 1/T2 + 2.391 107 1/T3 − 3.541 109 1/T4) + 0.1856 Δ48 (CDES 90) (‰) = 1.028 (6.002 1/T − 1.299 104 1/T2 + 8.996 106 1/T3 − 7.423 108 1/T4) + 0.1245 with CDES 90 representing the Carbon Dioxide Equilibrium Scale at a reaction temperature of 90 °C. In its entire temperature range, our Δ47 (CDES 90) - T - relationship agrees within 2 ppm with two previous Δ47 (I-CDES) - T - relationships reported by Jautzy et al. (2020) and Anderson et al. (2021). Accuracy of our proposed Δ47 (CDES 90) − Δ48 (CDES 90) equilibrium relationship is independently confirmed by additional dual clumped isotope data of experimental and geothermal carbonates which precipitated from potentially equilibrated dissolved inorganic carbon pools at a temperature range of 25–100 °C. Furthermore, we reprocessed original dual clumped isotope data of natural carbonates (Bajnai et al., 2020) and compared their composition to the position of equilibrium in Δ47 vs Δ48 space. These results corroborate preliminary evidence that the hydration/hydroxylation reactions became rate-limiting during the calcification of a speleothem-like sample, a warm water coral, a cold water coral and a brachiopod, finally evoking significant departures of carbonate-Δ47 and -Δ48 from dual clumped isotope equilibrium. An anti-clumped Δ48 value of −419 (±16) ppm (95% confidence interval level) is obtained for a technical calcite that was precipitated by the injection of CO2 into a Ca(OH)2-saturated solution. Its negative Δ48 value largely arises from a combinatorial effect, i.e. the carbonate oxygen derives from two sources with different bulk isotopic compositions. Besides the identification of the nature and the extent of (bio)mineralization kinetics and the reconstruction of carbonate formation temperatures unbiased by kinetics, dual clumped isotope analysis, therefore, allows tracing the isotopic heterogeneity of oxygen pools contributing to carbonate formation.
Published: 2021

21. Late Quaternary vegetation and climate of SE Europe - NW Asia according to pollen records in three offshore cores from the Black and Marmara seas

Author: Séverine Fauquette, Speranta Maria Popescu, Liviu Giosan, M. Namık Çağatay, Michel Calleja, Gonzalo Jiménez-Moreno, Gilles Lericolais, Stefan Klotz, François Guichard, Jean-Pierre Suc, GeoBioStratData.Consulting, University of Granada [Granada], Eberhard Karls Universität Tübingen, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Istanbul Technical University (ITÜ), Woods Hole Oceanographic Institution (WHOI), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226, Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GeoBioStratData.Consulting, Rillieux la Pape, France, Departamento de Estratigrafia y paleontologia, Université de grenade, Karl-Eberhardt Universität Tübingen, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Faculty of Mining, Istanbul, Geology and Geophysics Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS)
Subjects: Mediterranean climate, 010506 paleontology, Last Glacial – Holocene pollen flora, Steppe, [SDE.MCG]Environmental Sciences/Global Changes, Climate reconstruction, 010502 geochemistry & geophysics, medicine.disease_cause, 01 natural sciences, Last Glacial&#8211, Vegetation dynamics, Marmara Sea regions, W Black Sea&#8211, Pollen, medicine, Younger Dryas, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, biology, Zelkova, Paleontology, Geology, Vegetation, 15. Life on land, biology.organism_classification, Climatostratigraphy, W Black Sea – Marmara Sea regions, Plant diversity, 13. Climate action, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Physical geography, Quaternary, Holocene pollen flora
Abstract: International audience; High-resolution pollen analyses were performed on two cores from the western Black Sea and one core from the Marmara Sea, covering the Late Glacial-Holocene transition using 14C chronology. Particular effort was invested in the botanical identification of pollen grains thereby significantly improving our knowledge of regional flora. When interpreted with respect to modern vegetation, pollen records revealed all the major changes caused by climatic fluctuations over the last 20,000 years. The results of this study provide evidence for the occurrence of relict thermophilous-hygrophilous trees (papillate Cupressaceae, Carya, Liquidambar, Zelkova) in certain refugia up to the Holocene. Vegetation dynamics is specified for some taxa (e.g. Cupressus–Juniperus, Fagus, Cedrus) and some ecosystems (e.g. mesophilous forests, Mediterranean sclerophyllous populations, steppes). Pollen data enabled palaeoclimatic reconstructions which were compared with available estimates in the region. The use of a powerful pollen ratio between ‘thermophilous and steppe taxa’ led to fruitful climatostratigraphic relationships with the oxygen isotope curve from the NGRIP core. The Younger Dryas and cooling at 8.2 ka are among the most obvious climatic phases identified in the three cores studied here.
Published: 2021

22. Tephrochronological constraints on the timing and nature of sea-level change prior to and during glacial termination V

Author: Gianluca Marino, Gianluca Sottili, Hervé Guillou, Sébastien Nomade, Danilo M. Palladino, Fabrizio Marra, Alison Pereira, Lorenzo Monaco, Niklas Leicher, Mario Gaeta, Biagio Giaccio, Vincent Scao, Giovanni Zanchetta, Istituto di Geologia Ambientale e Geoingegneria, CNR, Rome, Italy, Consiglio Nazionale delle Ricerche [Roma] (CNR), Universidade de Vigo, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento di Scienze della Terra, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Scienze della Terra [Pisa], University of Pisa - Università di Pisa, University of Cologne, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), G.M. acknowledges support from the University of Vigo's programme to attract excellent research talent (RR04092017), a Beatriz Galindo Fellowship (2020), and a generous start-up package., Istituto di Geologia Ambientale e Geoingegneria (IGAG), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Marine isotope stage, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Pleistocene, 40Ar/39Ar geochronology, Fluvial, 01 natural sciences, Paleontology, Ar, 39, Ar geochronology, Aggradational successions, Heinrich-like events, Meltwater pulse events, Middle pleistocene, MIS 12 to MIS 11 transition, Aggradation, Glacial period, Tephra, Meltwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Sea level, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, meltwater pulse events, Global and Planetary Change, aggradational successions, Geology, 13. Climate action
Abstract: International audience; Glacial-interglacial variations in ice volume and sea level are essential components of the Pleistocene global climate evolution. Deciphering the timing of change of these key climate parameters with respect to the insolation forcing is central to understanding the processes controlling glacial terminations. Here we exploit the sensitivity of the Paleo Tiber River (central Italy) to sea-level forced changes in the base level and the frequent occurrence of datable tephra layers in its sedimentary successions to reconstruct the timing of the relative sea-level (RSL) change between 450 and 403 ka, i.e., across the glacial termination (T-V) that marks the transition between Marine Isotope Stage (MIS) 12 and MIS 11. The analysis hinges on new stratigraphic data, tephra geochemical fingerprinting, and 40Ar/39Ar dating from a fluvial section that represents the inland counterpart of the near mouth, coastal aggradational successions of the San Paolo Formation (SPF). Tephra correlation indicates that the morpho-stratigraphic record of the inland section is as sensitive to the sea-level change as its coastal counterparts, which makes it ideal to complement previous RSL reconstructions from the Tiber River catchment basin, thereby providing a more detailed picture of the sea-level history across T-V. Combined sedimentological and morphological proxies of the composed inland-coastal SPF record document the occurrence of two phases of relatively rapid sea-level rise, here interpreted as meltwater pulse (MWP) events. The earlier MWP occurred between ∼450 and ∼445 ka and matches a relatively minor episode of the sea-level rise documented in an existing RSL record, while the younger MWP at ∼430 ka corresponds to the high amplitude sea-level rise that marks T-V. We find that both MWPs coincide with episodes of ice-rafted debris deposition in the North Atlantic (Heinrich-like events) and with attendant Southern Hemisphere warming, plausibly associated with the bipolar seesaw.
Published: 2021

23. Southern Ocean upwelling, Earth’s obliquity, and glacial-interglacial atmospheric CO 2 change

Author: Elisabeth Michel, Julia Gottschalk, Gerald H. Haug, Anja S Studer, Lena M Thöle, Daniel M. Sigman, Mareike Schmitt, Laura Arnold, Sergey Oleynik, Alfredo Martínez-García, Simone Moretti, Samuel L Jaccard, Xuyuan E. Ai, François Fripiat, Department of Geosciences [Princeton], Princeton University, Department of Environmental Sciences [Basel], University of Basel (Unibas), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Université libre de Bruxelles (ULB), Institute of Geological Sciences [Bern], University of Bern, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Carbon dioxide in Earth's atmosphere, Multidisciplinary, 010504 meteorology & atmospheric sciences, Pleistocene, 010502 geochemistry & geophysics, 01 natural sciences, Sciences de la terre et du cosmos, chemistry.chemical_compound, Oceanography, chemistry, 13. Climate action, Interglacial, Carbon dioxide, Ice age, Deglaciation, Upwelling, 14. Life underwater, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Previous studies have suggested that during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean’s Antarctic Zone, which reduced the leakage of deeply sequestered carbon dioxide and thus contributed to the lower atmospheric carbon dioxide levels of the ice ages. Here, high-resolution diatom-bound nitrogen isotope measurements from the Indian sector of the Antarctic Zone reveal three modes of change in Southern Westerly Wind–driven upwelling, each affecting atmospheric carbon dioxide. Two modes, related to global climate and the bipolar seesaw, have been proposed previously. The third mode—which arises from the meridional temperature gradient as affected by Earth’s obliquity (axial tilt)—can explain the lag of atmospheric carbon dioxide behind climate during glacial inception and deglaciation. This obliquity-induced lag, in turn, makes carbon dioxide a delayed climate amplifier in the late Pleistocene glacial cycles., info:eu-repo/semantics/published
Published: 2020

24. Overturning circulation, nutrient limitation, and warming in the Glacial North Pacific

Author: Andrea Burke, Patrick A. Rafter, Ian Eisenman, Ben Fitzhugh, Eloise Littley, Andy Ridgwell, James W. B. Rae, William R Gray, Rhian L. Rees-Owen, Ben J Taylor, Robert C. J. Wills, M. Fotheringham, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), NERC, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Subtropics, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Beringia, Latitude, Nutrient, SDG 13 - Climate Action, 14. Life underwater, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, R2C, ComputingMilieux_MISCELLANEOUS, Research Articles, 0105 earth and related environmental sciences, GC, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, SciAdv r-articles, Last Glacial Maximum, DAS, social sciences, humanities, Salinity, Climate Action, 13. Climate action, Environmental science, Thermohaline circulation, GC Oceanography, BDC, geographic locations, Research Article
Abstract: Enhanced overturning circulation in the glacial North Pacific caused warming, nutrient limitation, and lower atmospheric CO2., Although the Pacific Ocean is a major reservoir of heat and CO2, and thus an important component of the global climate system, its circulation under different climatic conditions is poorly understood. Here, we present evidence that during the Last Glacial Maximum (LGM), the North Pacific was better ventilated at intermediate depths and had surface waters with lower nutrients, higher salinity, and warmer temperatures compared to today. Modeling shows that this pattern is well explained by enhanced Pacific meridional overturning circulation (PMOC), which brings warm, salty, and nutrient-poor subtropical waters to high latitudes. Enhanced PMOC at the LGM would have lowered atmospheric CO2—in part through synergy with the Southern Ocean—and supported an equable regional climate, which may have aided human habitability in Beringia, and migration from Asia to North America.
Published: 2020

25. Climate variability during MIS 20–18 as recorded by alkenone-SST and calcareous plankton in the Ionian Basin (central Mediterranean)

Author: Marina Addante, Maria Marino, Ornella Quivelli, Salvatore Gallicchio, Angela Girone, Franck Bassinot, Neri Ciaranfi, Adele Bertini, Patrizia Maiorano, Pietro Bazzicalupo, Timothy D Herbert, Sébastien Nomade, University of Bari Aldo Moro (UNIBA), Brown University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro (UNIBA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Università degli Studi di Firenze = University of Florence (UniFI)
Subjects: Marine isotope stage, Mediterranean climate, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, Paleontology, Sapropel, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Mediterranean Basin, Sea surface temperature, 13. Climate action, 14. Life underwater, Stadial, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Geology, Sea level, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Teleconnection
Abstract: This study shows the first Mediterranean high-resolution record of alkenone-derived sea surface temperature (SST) in the marine sediments outcropping at the Ideale section (IS) (southern Italy, central Mediterranean) from late marine isotope stage (MIS) 20 - through early MIS 18. The SST pattern evidences glacial-interglacial up to submillennial-scale temperature variation, with lower values (~13 °C) in late MIS 20 and substage 19b, and higher values (up to 21 °C) in MIS 19c and in the interstadials of MIS 19a. The SST data are combined with the new calcareous plankton analysis and the available, chronologically well-constrained carbon and oxygen isotope records in the IS. The multi-proxy approach, together with the location of the IS near the Italian coasts, the lower circalittoral-upper bathyal depositional setting, and high sedimentation rate allow to document long-and short-term paleoenvironmental modifications (sea level, rainfall, inorganic/organic/fresh water input to the basin), as a response to regional and global climate changes. The combined proxies reveal the occurrence of a terminal stadial event in late MIS 20 (here Med-HTIX), and warm-cold episodes (here Med-BATIX and Med-YDTIX) during Termination IX (TIX), which recall those that occurred through the last termination (TI). During these periods and the following ghost sapropel layer (insolation cycle 74, 784 ka) in the early MIS 19, high frequency internal changes are synchronously recorded by all proxies. The substage MIS 19c is warm but quite unstable, with several episodes of paleoenvironmental changes, associated with fluctuating tropical-subtropical water inflow through the Gibraltar Strait, variations of the cyclonic regime in the Ionian basin, and the southward shift of westerly winds and winter precipitation over southern Europe and Mediterranean basin. Three high-amplitude millennial-scale oscillations in the patterns of SST and calcareous plankton key taxa during MIS 19a are interpreted as linked to changes in temperature as well as in salinity due to periodical water column stratification and mixing. The main processes involved in the climate variability include changes in oceanographic exchanges through the Gibraltar Strait during modulations of Atlantic meridional overturning circulation and/or variations in atmospheric dynamics related to the influence of westerly and polar winds acting in the paleo-Ionian basin. A strong climate teleconnection between the North Atlantic and Mediterranean is discussed, and a prominent role of atmospheric processes in the central Mediterranean is evidenced by comparing data sets at the IS with Italian and extra-Mediterranean marine and terrestrial records.
Published: 2020

26. Dynamics of primary productivity in the northeastern Bay of Bengal over the last 26 000 years

Author: Stéphanie Duchamp-Alphonse, Franck Bassinot, Xinquan Zhou, Masa Kageyama, Christophe Colin, Luc Beaufort, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, lcsh:Environmental protection, Stratigraphy, Stratification (water), 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Bølling-Allerød, Water column, lcsh:Environmental pollution, Deglaciation, lcsh:TD169-171.8, Stadial, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Paleontology, Last Glacial Maximum, 15. Life on land, Oceanography, 13. Climate action, lcsh:TD172-193.5, BENGAL, Geology
Abstract: At present, variations of primary productivity (PP) in the Bay of Bengal (BoB) are driven by salinity-related stratification, which is controlled by the Indian summer monsoon (ISM). The relationships between PP, precipitation, and more generally climate in the past are not clearly understood. Here, we present a new record of PP based on the examination of coccolithophore assemblages in a 26 000-year sedimentary series retrieved in the northeastern BoB (core MD77-176). We compare our PP records to published climate and monsoon records, as well as outputs from numerical experiments obtained with the Earth system model IPSL-CM5A-LR, including the marine biogeochemical component PISCES, and with the transient climate simulation TraCE-21. Our results show that PP was most probably controlled by nutrient contents and distribution within the upper water column, which were predominantly influenced by (i) regional river systems between 26 and 19 ka, i.e. when sea level was relatively low and climate was relatively dry, and (ii) salinity-related stratification over the last 19 kyr, i.e. when sea level rose and more humid conditions prevailed. During that period, salinity and stratification were directly related to monsoon precipitation dynamics, which were chiefly forced by both insolation and Atlantic meridional overturning circulation (AMOC) strength. During Heinrich Stadial 1 and the Younger Dryas, i.e. when the AMOC collapsed, weaker South Asian precipitation diminished stratification and enhanced PP. During Bølling–Allerød, i.e. when the AMOC recovered, stronger South Asian precipitation increased stratification and subdued PP. Similarly, the precipitation peak recorded around the middle–early Holocene is consistent with a stronger stratification that drives PP minima.
Published: 2020

27. Marine and terrestrial climate variability in the western Mediterranean Sea during marine isotope stages 20 and 19

Author: Franck Bassinot, Maria Marino, Francesco Toti, Patrizia Maiorano, Nathalie Combourieu-Nebout, Sébastien Nomade, Antonella Buccianti, Adele Bertini, Angela Girone, Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Università degli studi di Bari Aldo Moro (UNIBA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Histoire naturelle de l'Homme préhistorique (HNHP), Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence (UniFI), Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro (UNIBA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Palynology, Mediterranean climate, Marine isotope stage, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, Archeology, Global and Planetary Change, 010504 meteorology & atmospheric sciences, Orbital forcing, biology, Geology, 15. Life on land, biology.organism_classification, 01 natural sciences, Foraminifera, Oceanography, Mediterranean sea, 13. Climate action, 14. Life underwater, Stadial, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences
Abstract: The climate variability within late Marine Isotope Stage (MIS) 20 and MIS 19 is examined with particular reference to the response of marine and terrestrial realms in the area surrounding the Alboran Sea (western Mediterranean Sea). Sediment samples from the Ocean Drilling Program Site 976 were used to derive high temporal resolution (average resolution of 450 years) palynological (pollen and spores) and calcareous plankton (coccolithophores and foraminifera) records. These data, together with the new δ18OG.bulloides, make it possible to discuss the paleoenvironmental changes within a well constrained chronological frame. Cooler phases, including late MIS 20 and several cold spells during MIS 19b-a, are marked, on land, by the expansion of open vegetation formations dominated by steppe and semi-desert taxa. At the same time, the western Mediterranean Sea is marked by the incursion of North Atlantic polar-water planktonic taxa. MIS 19c and interstadials of MIS 19b-a are characterized by the spread of prevalent temperate forest taxa that parallel the expansion of warm-water calcareous plankton taxa during periods of lighter δ18O. Climate variations at both precessional and millennial to sub-millennial time-scales, expressed by on land and marine signals, highlight the sensitivity of the western Mediterranean area to both orbital forcing and rapid internal oscillations of the climate systems involving remote connections with North Hemisphere high latitudes. The correlation within the central-western Mediterranean and North Atlantic climate dynamics including the time/spatial gradients related to regional and global climate processes contributes to the reconstruction of the Earth climate dynamics and marine vs land responses, in full Early-Middle Pleistocene transition. These new evidences also provide an opportunity to improve knowledge of MIS 19c now considered, due to its orbital geometry, the best orbital analogue to the Holocene.
Published: 2020

28. Tephrochronology of the central Mediterranean MIS 11c interglacial (∼425–395 ka): New constraints from the Vico volcano and Tiber delta, central Italy

Author: Mario Gaeta, Danilo M. Palladino, Vincent Scao, Niklas Leicher, Hervé Guillou, Fabrizio Marra, Alison Pereira, Biagio Giaccio, Sébastien Nomade, Gianluca Sottili, Lorenzo Monaco, Ecole française de Rome (EFR), Muséum national d'Histoire naturelle (MNHN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Dipartimento di Scienze della Terra, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institute of Geology and Mineralogy, University of Cologne, Zuelpicher Str. 49b, 50674 Cologne, Germany, Istituto di Geologia Ambientale e Geoingegneria, Consiglio Nazionale delle Ricerche (CNR), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of Cologne, Istituto di Geologia Ambientale e Geoingegneria (IGAG), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)
Subjects: Marine isotope stage, Archeology, 40Ar/39Ar, central Mediterranean, MIS 11c interglacial, tephrochronology, Vico volcano, 010504 meteorology & atmospheric sciences, Pyroclastic rock, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, 40 39 Ar/ Ar, Glacial period, Tephra, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Geology, Volcanology, Volcano, 13. Climate action, Interglacial, Tephrochronology
Abstract: Through a systematic integrated approach, which combined lithostratigraphic, geochronological and geochemical analyses of tephra from near-source sections of the peri-Tyrrhenian volcanoes and mid to distal settings, here we provide an improved tephrochronological framework for the Marine Isotope Stage 11c interglacial (MIS 11c, ∼425–395 ka) in the Central Mediterranean area. Specifically, we present the complete geochemical dataset and new high-precision 40Ar/39Ar ages of the previously poorly characterized earliest pyroclastic products of the Vico volcano (420–400 ka), including the Plinian eruptions of Vico α and Vico β and the immediately post-dating lower magnitude explosive events. Furthermore, we also provide new geochronological and geochemical data for the distal tephra layers preserved in the aggradational succession of the Tiber delta (San Paolo Formation), Roman area, which records sea level rise relating to the MIS 12 (glacial) to MIS 11 (interglacial) transition. Five pyroclastic units were recognized in Vico volcanic area, four out of which, Vico α, Vico β, Vico βtop (a minor eruption immediately following Vico β and temporally very close to it) and Vico δ were directly dated at 414.8 ± 2.2 ka, 406.5 ± 2.4 ka, 406.4 ± 2.0 ka and 399.7 ± 3.2 ka respectively (2σ analytical uncertainties). These new data allow a critical reappraisal of the previously claimed identifications of Vico tephra from mid-distal to ultra-distal successions (i.e., Vico-Sabatini volcanic districts, Roman San Paolo Formation and Castel di Guido archaeological site, Sulmona Basin, Valdarno and Lake Ohrid), which were unavoidably biased by the poor and incomplete geochemical and geochronological reference datasets previously available. Such an improvement of the tephrochronological framework brings great benefits to any future investigations (e.g., paleoclimatology, archaeology, active tectonic, volcanology) in the dispersal areas of the studied eruptions at the key point in time that is MIS 11.
Published: 2020

29. Ventilation and Expansion of Intermediate and Deep Waters in the Southeast Pacific During the Last Termination

Author: Fabien Dewilde, E. Michel, Giuseppe Siani, N. A. Haddam, L. Licari, Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, Paleontology, 16. Peace & justice, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, law.invention, 13. Climate action, law, Ventilation (architecture), 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, Geology, 0105 earth and related environmental sciences
Abstract: We investigate the geometry and ventilation of the water masses within bathyal depths (~1500 – ~2500 m) of the Southeast Pacific (SEP), inferring the lower depth limit variations of the Antarctic Intermediate Water (AAIW) since ~22 kyr cal. BP. We use three cores collected at the upper limit of the Pacific Deep Waters, between 41°S and 49°S and one core at a greater depth within this same water mass, at 46°S. The benthic foraminiferal assemblages and carbon and oxygen isotopes are used to show strong linkages between the timing of the deglacial Southern Ocean upwelling events and changes in the vertical extension and ventilation of the AAIW. In accordance with local/sub‐local oxygen reconstructions, we propose at least 3 states of ventilation–AAIW vertical extension; i) the late glacial and the Antarctic Cold Reversal (ACR): AAIW depth‐limit shoals, as its formation zone moves northward, ii) the deglaciation (excluding the ACR): the [O2] enrichment of the AAIW and the dominance of benthic species Trifarina angulosa indicate ventilated AAIW, along with a deepening of its lower limit, iii) the Holocene: enhanced influence of the Pacific Deep Water at bathyal depths (1500‐2500 m) in the SEP north of ~46°S, and the Circumpolar Deep Water south of ~46°S.
Published: 2020

30. North Indian Ocean circulation since the last deglaciation as inferred from new elemental ratio records for benthic foraminifera Hoeglundina elegans

Author: Frédéric Haurine, Franck Bassinot, Nadine Tisnérat-Laborde, Sophie Sépulcre, Christophe Colin, Ruifang Ma, Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géochrononologie Traceurs Archéométrie (GEOTRAC), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, carbonate ion concentration, 010502 geochemistry & geophysics, Oceanography, deglaciation, 01 natural sciences, Foraminifera, Deglaciation, North Indian Ocean, Circulation (currency), 14. Life underwater, Hoeglundina elegans, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, benthic elemental ratios, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, atmospheric CO2, biology, AAIW, Paleontology, biology.organism_classification, Indian ocean, 13. Climate action, Benthic zone, Geology
Abstract: International audience; The evolution of intermediate circulation in the northern Indian Ocean since the last deglaciation has been reconstructed from two marine cores located at intermediate depths off the southern tip of India (MD77‐191) and in the northern Bay of Bengal (BoB) (MD77‐176). Benthic foraminiferal δ13C, seawater carbonate ion concentration ([CO32−]) estimated from the Sr/Ca, and paleotemperature reconstructed on the basis of the Mg/Li of aragonite benthic species Hoeglundina elegans were used to trace the evolution of past intermediate‐deepwater masses and to constrain ocean‐atmosphere exchanges during the two‐stage increase in atmospheric CO2 across the last deglaciation. The intermediate water [CO32−] was mainly affected by changes in the ocean alkalinity inventory, associated with the modulation of atmospheric CO2 on glacial‐interglacial timescales. Higher benthic foraminiferal δ13C, depleted [CO32−], and decreased benthic‐planktonic 14C age offsets at intermediate water depths suggest a release of deep‐sea CO2 to the atmosphere through the Antarctic Intermediate Water (AAIW) in the Southern Ocean during the 17–15.2 and 12.6–10.5 cal kyr BP time intervals. In addition, the decreased H. elegans Mg/Li record seems to reflect an increased contribution of cold water mass during the 17–15.2 and 12.6–11.9 cal kyr BP intervals and throughout the Holocene. In contrast, two warm events occurred in the 15–13.3 and 11–10.3 cal kyr BP time intervals. During the late Holocene, a decrease in the intermediate water [CO32−] indicates a contribution to atmospheric CO2 rise since 8 cal kyr BP, due to the depleted global ocean alkalinity and/or the variations in surface productivity (at least for MD77‐191).
Published: 2020

31. Changes in temperature and oxygen isotopic composition of Mediterranean water during the Mid-Pleistocene transition in the Montalbano Jonico section (southern Italy) using the clumped-isotope thermometer

Author: Dominique Blamart, Mathieu Daëron, Sébastien Nomade, Angela Girone, Marion Peral, Franck Bassinot, Maria Marino, Patrizia Maiorano, Helene Rebaubier, Neri Ciaranfi, Fabien Dewilde, Analytical, Environmental & Geo-Chemistry, Chemistry, Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro (UNIBA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and University of Bari Aldo Moro (UNIBA)
Subjects: Mediterranean climate, 010506 paleontology, δ18O, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Mg/Ca, Paleothermometer, Mediterranean sea, Paleoceanography, paleothermometry, MIS 31, stable isotope, 14. Life underwater, Glacial period, MIS 19, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, foraminifera, Paleontology, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Interglacial, Seawater, Thermocline, Geology
Abstract: International audience; Taking advantage of the recent clumped-isotope methodological developments, the present study focuses on the reconstruction of temperatures and seawater δ18O in the central Mediterranean Sea across the Mid-Pleistocene section from Montalbano Jonico (south of Italy). Our results suggest that Mg/Ca paleothermometer can be biased over several intervals, making clumped-isotope a promising choice to reconstruct past changes in seawater temperature and isotopic composition in the Mediterranean Sea. Our results provide the first clumped-isotope temperature and δ18OSW reconstruction across several glacial and interglacial Marine Isotope Stages from MIS 36 to MIS 19 in the central Mediterranean Sea.During the climatic optimums of MIS 31 and MIS 19, considered as close analogues to the current interglacial in terms of insolation forcing, reconstructed average sub-surface temperatures from benthic foraminifer analyses (13.8 ± 1.5 °C and 14.8 ± 1.3 °C, respectively) and isotopic composition of seawater (between 1.6 ± 0.4‰ and 2.0 ± 0.3‰) are similar to the ones measured today below the thermocline in the Gulf of Taranto. Our results show that bottom water conditions remained similar in all the studied glacial periods, with cold temperatures around ~ 8 °C in average. The lack of a clear cooling across the Mid-Pleistocene either suggest that glacial oceanographic conditions in the Mediterranean Sea remained relatively stable between the 41 ka-world and the 100 ka-world or that the tectonic uplift that took place during this transition balanced out the MPT cooling trend through the shallowing of the deposition site.
Published: 2020

32. Volcanoes and climate: the triggering of preboreal Jökulhlaups in Iceland

Author: Oskar Knudsen, Céline Liorzou, Agust Guðmundsson, Hervé Guillou, Jessica Langlade, Philippe Nonnotte, Brigitte Van Vliet-Lanoë, Gilles Chazot, Laboratoire Géosciences Océan (LGO), Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS), Reykjavík University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Askja S, Iceland, Permafrost, 010502 geochemistry & geophysics, 01 natural sciences, Flood, Saksunarvatn tephra, Glacio-isostatic rebound, Saksunarvatn event, Deglaciation, Glacial, Younger Dryas, Glacial period, Tephra, Meltwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Geomorphology, Sedimentology, Preboreal, 13. Climate action, General Earth and Planetary Sciences, Physical geography, Geology
Abstract: International audience; The Early Holocene (12-8.2 cal ka) deglaciation and pulsed warming was associated in Iceland with two major generations of jökulhlaups around the Vatna ice-cap (Vatnajökull), at ca 11.4-11.2 cal ka and ca 10.4-9.9 cal ka, and major tephra emissions from the Grímsvötn and Bárðarbunga subglacial volcanoes. The earliest flood events were recorded inland during the Middle Younger Dryas and their deposits were overlain by the Early Preboreal Vedde Ash (11.8 cal ka). The first Holocene flood events (ca 11.4-11.2 cal ka) are issued from a glacial advance. The second, and major, set of floods was partly driven by the Erdalen cold events and advances (10.1-9.7 10Be ka) initially issued from the Bárðarbunga (10.4, 10.1-9.9 ka) and Grímsvötn volcanoes (Saksunarvatn tephra complex, ca. 10.2-9.9 cal ka). These floods were also fed by the residual glacio-isostatic depressions below the Vatnajökull that enabled the storage of meltwaters in large subglacial lakes or aquifers until ca. 9.3 cal ka. This storage was enhanced by icedamming and permafrost, especially during the twinned Erdalen events. Due to the glacio-isostatic rebound, the general slope was nearly flat, and the valley was partly filled with sediments until ca 10.8 cal ka. Temporary lacustrine deposits in this valley resulted from the very broad splay of waters as for the ca 11.2 cal ka and ca 10.1-9.9 cal ka flood, due to regional permafrost. These floods had a potential duration of several months as they were mostly fed by climate-driven meltwater. The maximal volume evacuated by these events did not greatly exceed 1 × 106 m3 s−1 from the flood-affected transverse profile of the valleys that remain partly filled with sediments.
Published: 2020

33. Seawater paleotemperature and paleosalinity evolution in neritic environments of the Mediterranean margin: insights from isotope analysis of bivalve shells

Author: Valérie Chavagnac, M. de Rafélis, Romuald Jaillet, Didier Merle, Emmanuelle Vennin, Mathieu Daëron, J. Briard, Emmanuelle Pucéat, Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche en Paléontologie - Paris (CR2P), Muséum national d'Histoire naturelle (MNHN)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE31-0020,AMOR,Reconstruction modèle-données des climats du Cénozoique(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Mediterranean climate, Hydrological cycle, 010506 paleontology, Paleoclimate, δ18O, Coastal environment, Holocene climatic optimum, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Clumped isotopes, Foraminifera, Mediterranean sea, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Paleoclimatology, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Earth-Surface Processes, biology, Paleontology, 15. Life on land, biology.organism_classification, 6. Clean water, Middle Miocene, Climatic Optimum, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Paleosalinity, Seawater, Geology
Abstract: 19 pages; International audience; The first step of ice-sheet build-up on Antarctica at the Eocene-Oligocene boundary was followed by a phase of climate instability culminating during the Miocene with a warming event called the Middle Miocene Climate Optimum (MMCO), that ended with a marked cooling phase identified as the Middle Miocene Climate Transition (MMCT). While numerous benthic foraminifera δ18O and Mg/Ca data have been used to capture the global climate evolution during this interval of climate and ice-sheet instability, geochemical records from shallow-water carbonates still remain scarce. Yet such records are crucial to capture the diversity of regional environmental responses to global climate changes, and thus to better understand the behavior of our climate system during this critical interval. In this work, we test the potential of a multi-proxy approach (δ18O, clumped isotope (Δ47), strontium isotopes (87Sr/86Sr)) applied to bivalves recovered from the Liguro-Provencal Basin and Rhodano-Provencal basin (Northwestern of the Mediterranean Sea) to reconstruct the evolution of shallow seawater temperature and salinity in this region over the latest Oligocene to Middle Miocene interval (~10 Myrs). Our results highlight a local cooling in the northwestern Mediterranean Sea during the MMCO that contrasts with the warming observed in other regions, with seawater temperatures inferred from Δ47 analyses in the 13–18 °C range. These cool seawater temperatures recorded in the studied region during the MMCO are much cooler than those recorded in the open oceans, but are in agreement with the proliferation of bryozoan observed in the Castillon-Du-Gard area during this interval. Low bivalve δ18O values (−3.24‰ in average) are recorded during this episode are interpreted to reflect enhanced freshwater inputs, lowering local salinity and seawater δ18O. Such enhanced freshwater inputs point to a phase of enhanced hydrological cycle in the studied region, possibly linked to the global mid-Miocene warming event. Bivalve 87Sr/86Sr data mostly fall within the global seawater Sr isotope reference curve, but remain compatible with enhanced freshwater inputs during the Aquitanian and during the Langhian, as these inputs were probably not important enough to induce a large departure from the seawater curve at a regional scale.
Published: 2020

34. The nature of deep overturning and reconfigurations of the silicon cycle across the last deglaciation

Author: Matthew Dumont, Steven Grahame Moreton, Raja S. Ganeshram, Elisabeth Michel, Keira Dobby, Laetitia Pichevin, Xavier Crosta, Walter Geibert, Centre d'Etudes de la Neige (CEN), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), University of Edinburgh, School of Geosciences [Edinburgh], Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Scottish Universities Environmental Research Centre (SUERC), University of Glasgow-University of Edinburgh, University of St Andrews. School of Earth & Environmental Sciences, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Silicon, 010504 meteorology & atmospheric sciences, Pleistocene, Science, Antarctic Regions, General Physics and Astronomy, Antarctic sea ice, Oceanography, 010502 geochemistry & geophysics, 01 natural sciences, Deep sea, Article, General Biochemistry, Genetics and Molecular Biology, Abyssal zone, Palaeoceanography, Isotopes, Water Movements, Deglaciation, Ice Cover, Seawater, 14. Life underwater, Younger Dryas, lcsh:Science, Atlantic Ocean, History, Ancient, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, GE, Atmosphere, Ocean current, Temperature, Paleontology, Biological pump, DAS, General Chemistry, Biogeochemistry, Carbon Dioxide, Ocean sciences, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, lcsh:Q, Geology, GE Environmental Sciences
Abstract: Changes in ocean circulation and the biological carbon pump have been implicated as the drivers behind the rise in atmospheric CO2 across the last deglaciation; however, the processes involved remain uncertain. Previous records have hinted at a partitioning of deep ocean ventilation across the two major intervals of atmospheric CO2 rise, but the consequences of differential ventilation on the Si cycle has not been explored. Here we present three new records of silicon isotopes in diatoms and sponges from the Southern Ocean that together show increased Si supply from deep mixing during the deglaciation with a maximum during the Younger Dryas (YD). We suggest Antarctic sea ice and Atlantic overturning conditions favoured abyssal ocean ventilation at the YD and marked an interval of Si cycle reorganisation. By regulating the strength of the biological pump, the glacial–interglacial shift in the Si cycle may present an important control on Pleistocene CO2 concentrations., Global atmospheric CO2 varies between glacial–interglacial cycles. Here, the authors study these changes using Si records and how the Si flux and ocean circulation changes controlled the global Si distribution across the last deglaciation, based on high-resolution Si-isotope records from the Indian Sector Southern Ocean.
Published: 2020

35. Wind-driven evolution of the North Pacific subpolar gyre over the last deglaciation

Author: Andrea Burke, Paul J. Valdes, Robert C. J. Wills, David Ferreira, Ruza F. Ivanovic, James W. B. Rae, William H. G. Roberts, William R Gray, NERC, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Department of Atmospheric Sciences [Seattle], University of Washington [Seattle], School of Earth and Environmental Sciences [University St Andrews], University of St Andrews [Scotland], School of Earth and Environment [Leeds] (SEE), University of Leeds, Newcastle University [Newcastle], Department of Meteorology [Reading], University of Reading (UOR), School of Geographical Sciences [Bristol], University of Bristol [Bristol], Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: bepress|Physical Sciences and Mathematics, EarthArXiv|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology, 010504 meteorology & atmospheric sciences, Atmospheric circulation, bepress|Physical Sciences and Mathematics|Earth Sciences, Wind stress, F800, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, F600, 010502 geochemistry & geophysics, 01 natural sciences, Westerlies, Climate models, bepress|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology|Climate, Ocean gyre, bepress|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology, Deglaciation, SDG 13 - Climate Action, QE, 14. Life underwater, North Pacific, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, QC, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, EarthArXiv|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology|Climate, Last Glacial Maximum, DAS, 15. Life on land, Gyre circulation, EarthArXiv|Physical Sciences and Mathematics, Polar easterlies, QE Geology, Geophysics, Oceanography, QC Physics, 13. Climate action, Oxygen isotopes, General Earth and Planetary Sciences, Ice sheet, Geology
Abstract: International audience; North Pacific atmospheric and oceanic circulations are key missing pieces in our understanding of the reorganization of the global climate system since the Last Glacial Maximum. Here, using a basin-wide compilation of planktic foraminiferal δ 18 O, we show that the North Pacific subpolar gyre extended~3°further south during the Last Glacial Maximum, consistent with sea surface temperature and productivity proxy data. Climate models indicate that the expansion of the subpolar gyre was associated with a substantial gyre strengthening, and that these gyre circulation changes were driven by a southward shift of the midlatitude westerlies and increased wind stress from the polar easterlies. Using single-forcing model runs, we show that these atmospheric circulation changes are a nonlinear response to ice sheet topography/albedo and CO 2. Our reconstruction indicates that the gyre boundary (and thus westerly winds) began to migrate northward at~16.5 ka, driving changes in ocean heat transport, biogeochemistry, and North American hydroclimate. Plain language summary Despite the North Pacific's importance in the global climate system, changes in the circulation of this region since the last ice age are poorly understood. Today, the North Pacific Ocean has distinct properties north and south of~40°N: To the south, the warm surface waters form a circulation cell that moves clockwise (the subtropical gyre); to the north, the cold surface waters form a circulation cell that moves anticlockwise (the subpolar gyre). This difference in surface ocean circulation north and south of~40°N is determined by the wind patterns. Here, using a compilation of oxygen isotopes measured in the carbonate shells of fossil plankton from sediment cores across the basin, which tracks changes in the spatial pattern of temperature, we reconstruct how the position of the boundary between the gyres changed since the last ice age. Our results show that the boundary between the gyres was shifted southward by~3°during the last ice age; this indicates that the westerly winds were also shifted southward at this time. Using numerical simulations of the climate, we find that this ice age shift in the westerly winds is primarily due to the presence of a large ice sheet over North America.
Published: 2020

36. Chronostratigraphy, depositional patterns and climatic imprints in Lake Acigol (SW Anatolia) during the Quaternary

Author: Demory, F., Rambeau, C., Lebatard, A.-E., Perrin, M., Blawal, S., Andrieu-Ponel, V., Rochette, P., Alçiçek, Hülya, Boulbes, N., Bourlès, D., Helvaci, C., Petschick, R., Mayda, S., Moigne, A.-M., Nomade, S., Ponel, P., Vialet, A., Alçiçek, Mehmet Cihat, Aumaître, G., Keddadouche, K., ASTER Team, Ege Üniversitesi, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Albert-Ludwigs-Universität Freiburg, Laboratoire Image, Ville, Environnement (LIVE), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Pamukkale University, Department of Geology, Histoire naturelle de l'Homme préhistorique (HNHP), Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Dokuz Eylül University Department of Geology, J.W. Goethe Universität, Institut für Geowissenschaften, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany, Ege University, Department of Biology, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ECCOREV Research Federation, projet EPICA, ANR-11-LABX-0061,OTMed,Objectif Terre : Bassin Méditerranéen(2011), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Sedimentology, Albert-Ludwigs-Universität Freiburg, Centre Européen de Recherches Préhistoriques de Tautavel, Museum National d’Histoire Naturelle – UMR 7194, CNRS – Université de Perpignan Via Domitia, Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), and ANR: 11-LABX-0061,Labex OT- Med,ANR-11-LABEX-0061
Subjects: Paleomagnetism, paleoenvironment, reconstruction, 010504 meteorology & atmospheric sciences, Evaporite, Turkey, Stratigraphy, chronostratigraphy, 010502 geochemistry & geophysics, 01 natural sciences, Quaternary, Sedimentary depositional environment, Paleontology, paleoclimate, Earth and Planetary Sciences (miscellaneous), Chronostratigraphy, Paleoenvironmental reconstructions, Tephra, depositional environment, 0105 earth and related environmental sciences, lacustrine deposit, paleomagnetism, Geology, Quaternary paleoclimatic records, Lake sediment, 13. Climate action, Facies, [SDE]Environmental Sciences, Sedimentary rock, Paleomagnetic dating
Abstract: A 601 m long sedimentary sequence was drilled in Lake Acigöl, located in the lakes region of SW Anatolia, near the Denizli travertine from which the oldest hominin of Turkey was unearthed. Among all dating methods applied to the sedimentary sequence, paleomagnetism, through the recognition of geomagnetic chrons, was the most successful and led to a quasi linear age model, with the 601 m long sedimentary record covering the last 2.3 Ma. An attempt to use the atmospherically deposited 10Be as a dating method was not very successful but provides interesting clues on this new method. Long-term lake level changes are depicted through lithological variations, in particular the carbonates and evaporites abundance. This change could be influenced by both long term cooling during the last 2 Ma and tectonic activity, which may in particular be responsible for a maximum water depth at around 1.8 Ma. Despite active tectonic influence, the sedimentary facies description and the magnetic susceptibility record (cleaned from tephra intervals) show that climate fluctuations (i.e., glacial-interglacial alternations) are likely recorded in the sedimentary succession, with warm periods marked by enhanced carbonate precipitation and cold and dry periods characterized by more detrital input linked to reduced vegetation cover and consequently more erosion in the catchment area. Preliminary pollen data, used to interpret magnetic susceptibility fluctuations, show that an average dry and open landscape prevailed around Acigöl lake during the whole record. © 2019, 114Y723 Agricultural Marketing Service, AMS Agence Nationale de la Recherche, ANR Aligarh Muslim University, AMU Centre National de la Recherche Scientifique, CNRS, This research was funded by TUBITAK-CNRS bilateral cooperation with the grant number of 114Y723 during 2015–2017. The funds by 1) the ECCOREV Research Federation (OSU PYTHEAS, CNRS, AMU) for the project “ACIGOL”, 2) the Labex OT-MED (OSU PYTHEAS, CNRS, AMU) for the project BILAT, 3) and the projet EPICA (INSU 2018; Programme Tellus-INTERVIE) were received during 2017–2018. We thank the Wissenschaftliche Gesellschaft Freiburg im Breisgau for additional funding. We acknowledge the ALKIM Company for permitting us access and sampling to the core with special gratitude to Mr Hüseyin Ünlü (MSc) who was the director of ALKIM Company in Acigöl during the sampling and Mr. Mahmut Eser (MSc), the manager of the exploitation and Mr. Ünal Arık, present director of the company. The ASTER AMS national facility (CEREGE, Aix en Provence) is supported by the program INSU/CNRS INTERVIE, the ANR through the “Projets thématiques d'excellence” program for the “Equipements d'excellence” ASTER-CEREGE action and IRD. We thank S. Choy and L. Gacem for their help in the 9 Be measurements using the AAS of the LN2C (CEREGE). The data are archived at https://dx.doi.org/10.1594/PANGAEA.907658 . Appendix A, This research was funded by TUBITAK-CNRS bilateral cooperation with the grant number of 114Y723 during 2015?2017. The funds by 1) the ECCOREV Research Federation (OSU PYTHEAS, CNRS, AMU) for the project ?ACIGOL?, 2) the Labex OT-MED (OSU PYTHEAS, CNRS, AMU) for the project BILAT, 3) and the projet EPICA (INSU 2018; Programme Tellus-INTERVIE) were received during 2017?2018. We thank the Wissenschaftliche Gesellschaft Freiburg im Breisgau for additional funding. We acknowledge the ALKIM Company for permitting us access and sampling to the core with special gratitude to Mr H?seyin ?nl? (MSc) who was the director of ALKIM Company in Acig?l during the sampling and Mr. Mahmut Eser (MSc), the manager of the exploitation and Mr. ?nal Ar?k, present director of the company. The ASTER AMS national facility (CEREGE, Aix en Provence) is supported by the program INSU/CNRS INTERVIE, the ANR through the ?Projets th?matiques d'excellence? program for the ?Equipements d'excellence? ASTER-CEREGE action and IRD. We thank S. Choy and L. Gacem for their help in the 9Be measurements using the AAS of the LN2C (CEREGE). The data are archived at https://dx.doi.org/10.1594/PANGAEA.907658.
Published: 2020

37. Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: High-resolution calcareous plankton and molecular biomarker signals

Author: F. Bassinot, Teresa Rodrigues, Maria Marino, Emilia Salgueiro, Patrizia Maiorano, Ornella Quivelli, Fatima F Abrantes, Angela Girone, Università degli studi di Bari Aldo Moro (UNIBA), Dipartimento di Geologia e Geofisica, Universita di Bari, Universidade do Porto, Dipartimento Geol & Geofis, University of Bari Aldo Moro (UNIBA), Instituto Português de Investigação do Mar e da Atmosfera (IPMA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro (UNIBA), Universidade do Porto = University of Porto, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Marine isotope stage, Planktonic foraminifera, 010506 paleontology, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Terrigenous biomarkers, Foraminifera, Coccolithophores, C-37-alkenones, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, MIS 19, Organic-rich layer, Ecology, Evolution, Behavior and Systematics, Sea level, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Total organic carbon, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, biology, Paleontology, Globigerina bulloides, Plankton, biology.organism_classification, Sea surface temperature, 13. Climate action, Surface water, Geology
Abstract: We reconstructed changes in productivity and surface/subsurface and deep-water dynamics in the Western Mediterranean through a multi-proxy study of Ocean Drilling Program Site 975 between late Marine Isotope Stage (MIS) 20 and early interglacial MIS 19. Our high-resolution study (down to similar to 200-year resolution) combines calcareous plankton assemblages (coccolithophores and foraminifera), biomarkers (C-37-alkenones, n-alkanes, n-alcohols) and elemental proxies (total organic carbon, total nitrogen, calcium carbonate). Surface water conditions are derived (i) from high-resolution delta O-18 and delta C-13 records obtained from the planktonic foraminifer Globigerina bulloides, and (ii) from summer and winter, foraminifera-based sea surface temperature reconstructions (SSTJAS-foram, SSTJFM-foram) achieved through transfer function. The integration of the whole dataset makes it possible to identify in the Balearic Sea, and to accurately characterize for the first time, an Organic Rich Layer (ORL) during latest MIS 20-early MIS 19, close to i-cycle 74. Its presence is marked firstly by higher values of total nitrogen (TN) and an increase of total C-37-alkenone and total organic carbon (TOC) preserved in the sediments. The multi-proxy approach reveals that the deglacial phase played a prominent role for ORL formation that was characterized by centennial scale phases. The alcohol preservation index (API) suggests that the shoaling of the circulation, which boosted marine productivity, started in the deglaciation and, in combination with freshening by Atlantic water inflow/riverine input and surface water buoyancy during sea level rising, culminated during the ORL event. At this time calcareous plankton proliferated on subsurface-surface waters, benefiting from ameliorating conditions, which promoted maximum marine productivity and higher organic matter preservation on the seafloor. Geoscience PhD scholarship, University degli Studi di Bari Fundacao para a Ciencia e a TecnologiaPortuguese Foundation for Science and TechnologyEuropean Commission [SFRH/BPD/111433/2015] dell'Universita degli Studi di Bari, Laboratorio per lo Sviluppo Integrato delle Scienze e delle Tecnologie dei Materiali Avanzati e per dispositivi innovativi (SISTEMA) [PONa3_00369] info:eu-repo/semantics/publishedVersion
Published: 2020

38. Tectonism and volcanism enhanced by deglaciation events in southern Iceland

Author: Agust Guðmundsson, Sophie Passot, Christophe Innocentd, F. Bergerat, Jean-Luc Schneider, Gilles Chazot, Céline Liorzou, Pascal Allemand, Philippe Grandjean, Hervé Guillou, Brigitte Van Vliet-Lanoë, Thibault Cavailhes, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), University of Iceland [Reykjavik], Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Eemian, geography, geography.geographical_feature_category, Rift, 010504 meteorology & atmospheric sciences, Volcanism, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Arts and Humanities (miscellaneous), Volcano, 13. Climate action, Interglacial, Deglaciation, General Earth and Planetary Sciences, Glacial period, Ice sheet, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Southern Iceland is one of the main outlets of the Icelandic ice sheet and is subject to seismicity of both tectonic and volcanic origins along the South Iceland Seismic Zone (SISZ). A sedimentary complex spanning Marine Isotopic Stage 6 (MIS 6) to the present includes evidence of both activities. It includes a continuous sedimentary record since the Eemian interglacial period, controlled by a rapid deglaciation, followed by two marine glacioisostasy-forced transgressions, separated by a regression phase connected to an intra-MIS 5e glacial advance. This record has been constrained by tephrostratigraphy and dating. Analysis of this record has provided better insights into the interconnectedness of hydrology and volcanic and tectonic activity during deglaciations and glaciations. Low-intensity earthquakes recurrently affected the water-laid sedimentation during the early stages of unloading, accompanying rifting events, dyke injection, and fault reactivations. During full interglacial periods, earthquakes were significantly less frequent but of higher magnitude along the SISZ, due to stress accumulation, favored by low groundwater levels and more limited magma production. Occurrence of volcanism and seismicity in Iceland is commonly related to rifting events. Subglacial volcanic events seem moreover to have been related to stress unlocking related to limited or full unloading/deglaciation events. Major eruptions were mostly located at the melting margin of the ice sheet.
Published: 2020

39. Southern Ocean link between changes in atmospheric CO2 levels and northern-hemisphere climate anomalies during the last two glacial periods

Author: Luke C Skinner, Claire Waelbroeck, Laurie Menviel, Christoph Nehrbass-Ahles, Julia Gottschalk, Samuel L Jaccard, Oeschger Centre for Climate Change Research (OCCR), University of Bern, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM), Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA Research Centre), School of Biological, Earth and Environmental Sciences [Sydney] (BEES), University of New South Wales [Sydney] (UNSW)-University of New South Wales [Sydney] (UNSW), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Godwin Laboratory for Palaeoclimate Research, University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern]-Universität Bern [Bern], Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), European Project: 339108,EC:FP7:ERC,ERC-2013-ADG,ACCLIMATE(2014), Climate Change Research Centre, PANGEA, University of New South Wales, Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Convection, Interstadials, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, sub-01, [SDE.MCG]Environmental Sciences/Global Changes, Foraminifera, 01 natural sciences, Carbon cycle, Paleoclimatology, Ekman transport, Atmospheric CO2 variations, 14. Life underwater, Stadial, Glacial period, Southern Ocean, Dansgaard-Oeschger cycles, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Glacials, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, biology, Northern Hemisphere, Geology, biology.organism_classification, Oceanography, Stadials, Palaeoclimatology, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Environmental science, Redox-sensitive elements
Abstract: International audience; Past millennial-scale changes in atmospheric CO2 (CO2,atm) concentrations have often been attributed to variations in the overturning timescale of the ocean that result in changes in the marine carbon inventory. Yet, there remains a paucity of proxy evidence that documents changes in marine carbon storage globally, and that links them to abrupt climate variability in the northern hemisphere associated with perturbations of the Atlantic Meridional Overturning Circulation (AMOC). The last two glacial periods were suggested to differ in the spatial extent of the AMOC and its sensitivity to perturbations. This provides an opportunity to compare the nature of marine carbon cycle-climate feedbacks between them. Here, we reconstruct variations in respired carbon storage (via oxygenation) and the AMOC “geometry” (via carbonate ion saturation) in the deep South Atlantic. We infer decreases in deep South Atlantic respired carbon levels at times of weakened AMOC and rising CO2,atm concentrations during both glacial periods. These findings suggest a consistent pattern of increased Southern Ocean convection and/or air-sea CO2 fluxes during northern-hemisphere stadials accompanying AMOC perturbations and promoting a rise in CO2,atm levels. We find that net ocean carbon loss, and hence the magnitude of CO2,atm rise, is largely determined by the stadial duration. North Atlantic climate anomalies therefore affect Southern Ocean carbon cycling in a consistent manner, through oceanic (e.g., ventilation seesaw) and/or atmospheric processes (e.g., Ekman pumping).
Published: 2020

40. Geomorphology and tephrochronology review of the Hasandağ volcano (southern Cappadocia, Turkey)

Author: Catherine Kuzucuoğlu, Jean-François Pastre, Ahmet Türkecan, E. Gündoğdu Atakay, Hervé Guillou, Gokhan Atıcı, Damase Mouralis, Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Identités et Différenciation de l'Environnement des Espaces et des Sociétés (IDEES), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Identité et Différenciation de l’Espace, de l’Environnement et des Sociétés (IDEES), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire Homme et Société (IRIHS), Normandie Université (NU), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, Pyroclastic rock, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, General Medicine, 010502 geochemistry & geophysics, Dacite, 01 natural sciences, Paleontology, Volcano, 13. Climate action, Pumice, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Stratovolcano, Caldera, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Tephrochronology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: International audience; This research proposes a suite of volcanic events that took part in the edification of the double-peaked Hasandağ stratovolcano in southern Cappadocia. Inter-correlations of sections dispatched along geographic transects across the volcano evidence continuities/discontinuities and stratigraphic relationships using key layers identified through this process which is, later, framed by a radiometric dating control of some of these formations. The main goal is to provide some chronological markers of the geomorphological evolution of the volcano. The stratigraphy, lithology and facies, the landform definitions and new dates provide information about eruption types and their role in shaping the morphologies of the volcano through time. Recent ages from literature and seven new K/Ar dates contribute in enriching the story of the volcanic activity that built the Hasandağ stratovolcano landforms. The part of the story exposed in this article starts mainly c. 700/650 ka ago with the construction of a Mid-Pleistocene volcano. Later, between 220 and 120 ka ago, main events occurred in the NE part of the volcano. After an initial Plinian eruption, a caldera collapse is recorded by pumice flows. Close to the emission point, a small collapse structure is today filled with a much younger dacite flow. After the Plinian eruption, the partial destruction of a volcano caused one or two avalanches containing several meters-thick distinct blocks that flew north c. 16–18 km over the roof of the Cappadocian Miocene ignimbrites. Remains of the destructed volcano flanks are not visible. Either they are buried below younger lava flows forming the Küçük Hasandağ cone, or a seism in the Tuz Gölü Fault Zone during the avalanche may have resulted in an explosion. This event was followed by extrusion of rhyolitic domes positioned on the caldera rim, emitting pumice falls now filling-in the Güvercin valley stream down to Ihlara village. During Late Pleistocene emission of andesite and dacite flows and domes, accompanied by several pyroclastic flows formed today’s terminal cones of the stratovolcano.
Published: 2020

41. Insect decline: immediate action is needed

Author: Louis Lambrechts, Anna-Bella Failloux, Yvon Le Maho, Hervé Jactel, Jean-Dominique Lebreton, Philippe Grandcolas, Pascale Cossart, Jean-Luc Imler, Jean-Claude Duplessy, Biodiversité, Gènes & Communautés (BioGeCo), Université de Bordeaux (UB)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Modèles Insectes de l'Immunité Innée (M3I), Institut de biologie moléculaire et cellulaire (IBMC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Interactions Virus-Insectes - Insect-Virus Interactions (IVI), Centre National de la Recherche Scientifique (CNRS)-Institut Pasteur [Paris], Arbovirus et Insectes Vecteurs - Arboviruses and Insect Vectors, Institut Pasteur [Paris], Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Département Ecologie, Physiologie et Ethologie (DEPE-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Centre Scientifique de Monaco (CSM), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Interactions Bactéries-Cellules (UIBC), Institut National de la Recherche Agronomique (INRA)-Institut Pasteur [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), Institut Pasteur [Paris] (IP), Université Paul-Valéry - Montpellier 3 (UPVM)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Muséum national d'Histoire naturelle (MNHN)-École Pratique des Hautes Études (EPHE)
Subjects: 0106 biological sciences, 0301 basic medicine, Insecta, Pollination, media_common.quotation_subject, [SDV]Life Sciences [q-bio], Population, Biodiversity, Insect, Conservation, Biology, Extinction, Biological, 01 natural sciences, 03 medical and health sciences, Decline, Animals, Humans, Ecosystem, education, Global change, media_common, 2. Zero hunger, education.field_of_study, Agroforestry, business.industry, fungi, Agriculture, General Medicine, 15. Life on land, Pesticide, 030104 developmental biology, Habitat, 13. Climate action, [SDE]Environmental Sciences, business, 010606 plant biology & botany
Abstract: Insects appeared more than 400 million years ago and they represent the richest and most diverse taxonomic group with several million species. Yet, under the combined effect of the loss of natural habitats, the intensification of agriculture with massive use of pesticides, global warming and biological invasions, insects show alarming signs of decline. Although difficult to quantify, species extinction and population reductions are confirmed for many ecosystems. This results in a loss of services such as the pollination of plants, including food crops, the recycling of organic matter, the supply of goods such as honey and the stability of food webs. It is therefore urgent to halt the decline of Insects. We recommend implementing long-term monitoring of populations, tackling the causes of insect decline by reducing the use of synthetic insecticides, preserving natural habitats, and reinventing a positive relationship between humans and insects.Apparus il y a plus de 400 millions d’années, les Insectes représentent le groupe taxonomique le plus riche et diversifié, avec plusieurs millions d’espèces. Sous l’effet de la disparition des habitats, de l’intensification de l’agriculture avec l’usage massif des pesticides, du réchauffement climatique et des invasions biologiques, les Insectes montrent des signes alarmants de déclin. Bien que difficiles à quantifier, la disparition des espèces et la réduction de leurs populations sont avérées et communes à de nombreux écosystèmes. Elles se traduisent par une perte des services rendus, comme la pollinisation des plantes vivrières, le recyclage de la matière organique, la fourniture de biens comme le miel, et l’équilibre des réseaux trophiques. Il est donc urgent de freiner le déclin des Insectes. Pour cela, il faut mettre en œuvre des suivis à long terme des populations, réduire l’usage des insecticides de synthèse, préserver les habitats naturels, et réinventer la relation de l’Homme à l’Insecte en revalorisant son image et ses usages.
Published: 2020

42. Adaptation planning in France: Inputs from narratives of change in support of a community-led foresight process

Author: Charlotte da Cunha, Marianne Cardon, Florentin Breton, Laurent Labeyrie, Ana Paula Farias Rocha, Jean-Paul Vanderlinden, Cultures, Environnements, Arctique, Représentations, Climat (CEARC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Freelance designer, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Bretagne Sud (UBS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Atmospheric Science, Process management, 010504 meteorology & atmospheric sciences, Process (engineering), Geography, Planning and Development, Chronotopes, Narratives of changes, 010501 environmental sciences, Management, Monitoring, Policy and Law, lcsh:QC851-999, 01 natural sciences, [SHS]Humanities and Social Sciences, Political science, 11. Sustainability, Narrative, Local population, Adaptation (computer science), 0105 earth and related environmental sciences, Global and Planetary Change, Interpretation (philosophy), Gulf of Morbihan, Co-community-led foresight process, Identification (information), Futures studies, 13. Climate action, lcsh:Meteorology. Climatology, Prerogative, Art and science experimentation
Abstract: International audience; In France, integrating adaptation to climate change into planning policies is a prerogative that has recently been delegated to municipalities. There are also various injunctions to engage the local population in this decision-making process. How can municipalities co-construct an adaptive future with their citizens? This article critically describes a community-led foresight process, based on the mapping, analysis and interpretation of narratives of change. Based on empirical results, we explore and discuss the role past, present and future narratives may play in the process of outlining incremental scenarios and how these might enable the identification of pathways and hinge points. The role of design in supporting the process by proposing an innovative foresight workshop is also discussed. We then highlight how these narratives stimulated reflections through an art, design and science foresight experiment.
Published: 2020

43. Two Records of Relative Paleointensity for the Past 4 Myr

Author: Franck Bassinot, Jean-Pierre Valet, Tatiana Savranskaia, Anojh Thevarasan, Naoufel Haddam, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Paleomagnetism, 010504 meteorology & atmospheric sciences, Natural remanent magnetization, reversals, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Sediment, paleomagnetism, 010502 geochemistry & geophysics, magnetization, 01 natural sciences, paleointensity, Paleontology, Magnetization, Earth's magnetic field, 13. Climate action, Remanence, geomagnetic field, General Earth and Planetary Sciences, lcsh:Q, Sedimentary rock, lcsh:Science, Geology, Magnetostratigraphy, 0105 earth and related environmental sciences
Abstract: International audience; We performed new high-resolution magnetic measurements of sedimentary cores from the east northern Pacific ODP Site 1021 and the East equatorial Pacific ODP Site 851. ODP Site 1021 is characterized by a high clay content with less than 10% carbonates in contrast to ODP Site 851 which is highly carbonated (% CaCO 3 of at least 70%). The time scale of both records was obtained by orbital tuning of sediment density and/or susceptibility variations and whenever possible tested against the reversal positions. Previous magnetic studies at both sites have been concentrated on the past 1.2 Ma using U-channels. We extended this period and performed high resolution and detailed studies of 4210 sediment levels that cover the past 4.4 Ma. Natural remanent magnetization (NRM) and anhysteretic remanent magnetization (ARM) were both stepwise demagnetized by alternating fields. The new results confirm the magnetostratigraphy derived from the shipboard measurements but improve the definition of the polarity intervals and identify zones or events that were either unclear or hidden by unremoved secondary components. Studies of relative paleointensity were conducted following the standard rules and yielded determinations with the exception of intervals that were either too weakly magnetized or disturbed. The evolution of relative paleointensity displays similar behavior during the reversal periods at both sites, but the two curves show strikingly different patterns outside the transitional intervals that are characterized by the largest intensity changes. Spectral analyses revealed that magnetic concentration was strongly dependent on paleoenvironmental components at ODP Site 1021 which likely affected the results of relative paleointensity. It is assumed that the absence of any long-term geomagnetic trend during the stable polarity intervals at this site results from the interplay between climatic and geomagnetic factors. The large amplitude of field intensity decrease during the reversal periods dominates all other factors and is thus visible over the entire record.
Published: 2020

44. Climate‐Driven Weathering Shifts Between Highlands and Floodplains

Author: Christophe Colin, Germain Bayon, Shiming Wan, Franck Bassinot, Zhaojie Yu, Key Laboratory of Marine Geology and Environment [China, Institute of Oceanology [China], Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Géosciences Marines (GM)
Subjects: %22">carbon cycle, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Floodplain, %22">highlands and floodplains, Earth science, Climate change, Weathering, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Carbon cycle, Geophysics, 13. Climate action, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, %22">climate change, %22">continental weathering, %22">Himalaya, Geology, 0105 earth and related environmental sciences, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; Chemical weathering of silicate rocks on continents is thought to have played an important role in the evolution of past atmospheric carbon dioxide over geologic timescales. However, the detailed links between continental weathering and climate change over shorter timescales, and their potential impact on sediment records deposited in the ocean, remain poorly understood. Here, we present clay mineralogy and strontium-neodymium isotopic data for marine sediment records from the Northern Indian Ocean, with the aim of investigating the weathering response of large Himalayan river basins to orbital and millennial climate forcing. We show that past glaciated episodes of the late Quaternary corresponded to periods of increased physical erosion, associated with the preferential export of illite and chlorite assemblages from the Himalayan highlands having relatively radiogenic Sr isotopic signatures. In contrast, the warm periods of enhanced monsoon rainfall coincided with the transport of intensively weathered smectite-dominated soils derived from the floodplains, characterized by lower 87 Sr/ 86 Sr signatures. This finding suggests that the short-term climatic variability over late Quaternary timescales was accompanied by concomitant changes between high mountain-versus floodplain-dominated weathering regimes, with possible impact on the nature of weathered rocks and, as a consequence, on the carbon cycle.
Published: 2020

45. Radiogenic isotopic and clay mineralogical signatures of terrigenous particles as water-mass tracers: New insights into South Atlantic deep circulation during the last termination

Author: F. Beny, Aloys Bory, Nicolas Tribovillard, M. Delattre, Claire Waelbroeck, Viviane Bout-Roumazeilles, Gareth Davies, R. Abraham, Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Geology and Geochemistry, Earth Sciences, CLUE+, Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Université de Lille-Université du Littoral Côte d'Opale-Centre National de la Recherche Scientifique (CNRS), CNRS, UMR8187, Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: 010506 paleontology, Archeology, Water mass, 010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Last deglaciation, Grain size distribution, 01 natural sciences, Bottom water, South Atlantic, Paleoceanography, Circumpolar deep water, Deglaciation, 14. Life underwater, Younger Dryas, SDG 14 - Life Below Water, Southern Ocean, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Radiogenic isotopes, [PHYS]Physics [physics], Global and Planetary Change, Terrigenous sediment, North Atlantic Deep Water, Geology, Clay mineralogy, Oceanography, Antarctic Bottom Water, 13. Climate action, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences
Abstract: International audience; The past evolution of the Southern Ocean, one of the major components of the climatic system, is still a matter of debate. This study provides new insights into the deep Southern Ocean circulation based on the radiogenic isotopes and clay mineralogical signature of the terrigenous fractions transported by the main deep water masses to sediments recovered in core MD07-3076Q from the central South Atlantic. This approach successfully permits: (1) provenance identification of the various grain-size fractions (clay, cohesive silt and sortable silt); (2) assignment of each grain-size fraction to a specific water-mass; (3) reconstruction of past changes in the main deep water-mass pathways. These data document the evolution of deep-water masses in the South Atlantic Ocean during the last deglaciation. The Antarctic Bottom Water (AABW) speed and northward extension were maximum at the end of the Last Glacial Maximum (LGM), associated with strong bottom water production in the Weddell Sea, together with a vigorous Lower Circumpolar Deep Water (LCDW). In contrast the North Atlantic Deep Water (NADW) circulation was weaker than today. The onset of the deglaciation (from 17.5 ka to 15 ka,~Heinrich Stadial 1, HS 1) was marked by weakening and southerly retreat of the AABW and by an increase of mixing between AABW and LCDW. The speed of the AABW remained at its lowest during the Bølling Allerød (B/ A) and the Younger Dryas (YD), and the LCDW slowed and retreated to the south, while the NADW progressively migrated southward, deepened, and strengthened between the beginning of the Bølling Allerød and the Holocene (from~15 to 10 ka).
Published: 2020

46. Ventilation of the Deep Ocean Carbon Reservoir During the Last Deglaciation: Results From the Southeast Pacific

Author: Consuelo Martínez Fontaine, Lowell D. Stott, Ricardo De Pol-Holz, D Reyes-Macaya, Elisabeth Michel, John Southon, Giuseppe Siani, Tim DeVries, Dierk Hebbeln, Gema Martínez-Méndez, Mahyar Mohtadi, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Univ Chile, Dept Geol, Santiago, Univ Magallanes, Ctr Invest GAIA Antarct CIGA & Network Extreme En, Punta Arenas, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Univ Bremen, Ctr Marine Environm Sci, MARUM, Bremen, Department of Atmospheric and Oceanic Sciences [Los Angeles] (AOS), University of California [Los Angeles] (UCLA), University of California-University of California, Univ Southern Calif, Dept Earth Sci, Los Angeles, CA 90007, University of California [Irvine] (UCI), University of California, Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of California (UC)-University of California (UC), University of California [Irvine] (UC Irvine), and University of California (UC)
Subjects: Atmospheric Science, Antarctic Intermediate Water, 010504 meteorology & atmospheric sciences, biology, Ocean current, Paleontology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Last Glacial Maximum, 010502 geochemistry & geophysics, Oceanography, biology.organism_classification, 01 natural sciences, Deep sea, Foraminifera, Continental margin, 13. Climate action, [SDU]Sciences of the Universe [physics], Deglaciation, 14. Life underwater, Glacial period, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Coeval changes in atmospheric CO2 and C-14 contents during the last deglaciation are often attributed to ocean circulation changes that released carbon stored in the deep ocean during the Last Glacial Maximum (LGM). Work is being done to generate records that allow for the identification of the exact mechanisms leading to the accumulation and release of carbon from the oceanic reservoir, but these mechanisms are still the subject of debate. Here we present foraminifera C-14 data from five cores in a transect across the Chilean continental margin between similar to 540 and similar to 3,100 m depth spanning the last 20,000 years. Our data reveal that during the LGM, waters at similar to 2,000 m were 50% to 80% more depleted in Delta C-14 than waters at similar to 1,500 m when compared to modern values, consistent with the hypothesis of a glacial deep ocean carbon reservoir that was isolated from the atmosphere. During the deglaciation, our intermediate water records reveal homogenization in the Delta C-14 values between similar to 800 and similar to 1,500 m from similar to 16.5-14.5 ka cal BP to similar to 14-12 ka cal BP, which we interpret as deeper penetration of Antarctic Intermediate Water. While many questions still remain, this process could aid the ventilation of the deep ocean at the beginning of the deglaciation, contributing to the observed similar to 40 ppm rise in atmospheric pCO(2).
Published: 2019

47. Extending the tephra and palaeoenvironmental record of the Central Mediterranean back to 430 ka: A new core from Fucino Basin, central Italy

Author: Laura Sadori, Polychronis C Tzedakis, Gianluca Sottili, Lorenzo Monaco, Jonathan R. Dean, Thomas Wonik, Patrizia Macrì, Fabrizio Marra, Giovanni Zanchetta, Stephanie Scheidt, Camille Thomas, Melanie J. Leng, Niklas Leicher, Mario Gaeta, Paul R. Renne, Sébastien Nomade, Christian Rolf, Daniel Ariztegui, Alison Pereira, Biagio Giaccio, Fabio Florindo, Elizabeth M. Niespolo, Gian Paolo Cavinato, Bernd Wagner, Eleonora Regattieri, Christian Zeeden, Danilo M. Palladino, Sabine Wulf, Giorgio Mannella, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Marine isotope stage, Mediterranean climate, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, explosive volcanism, Structural basin, 01 natural sciences, Global and planetary change, Paleontology, central Mediterranean, Tephra, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Sediment core, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, potassic volcanism, paleoclimatology, Ecology, Evolution, Behavior and systematics, Geology, Archaeology, 13. Climate action, Geochronology, Fucino, Tephrochronology, tephrochronology
Abstract: Here we present the first tephrostratigraphic, palaeomagnetic, and multiproxy data from a new ∼98 m-deep sediment core retrieved from the Fucino Basin, central Italy, spanning the last ∼430 kyr. Palaeoenvironmental proxy data (Ca-XRF, gamma ray and magnetic susceptibility) show a cyclical variability related to interglacial-glacial cycles since the Marine Isotope Stage (MIS) 12-MIS 11 transition. More than 130 tephra layers are visible to the naked eye, 11 of which were analysed (glass-WDS) and successfully correlated to known eruptions and/or other equivalent tephra. In addition to tephra already recognised in the previously investigated cores spanning the last 190 kyr, we identified for the first time tephra from the eruptions of: Tufo Giallo di Sacrofano, Sabatini (288.0 ± 2.0 ka); Villa Senni, Colli Albani (367.5 ± 1.6 ka); Pozzolane Nere and its precursor, Colli Albani (405.0 ± 2.0 ka, and 407.1 ± 4.2 ka, respectively) and Castel Broco, Vulsini (419–490 ka). The latter occurs at the bottom of the core and has been 40Ar/39Ar dated at 424.3 ± 3.2 ka, thus providing a robust chronological constrain for both the eruption itself and the base of the investigated succession. Direct 40Ar/39Ar dating and tephra geochemical fingerprinting provide a preliminary radioisotopic-based chronological framework for the MIS 11-MIS 7 interval, which represent a foundation for the forthcoming multiproxy studies and for investigating the remaining ∼110 tephra layers that are recorded within this interval. Such future developments will contribute towards an improved MIS 11-MIS 7 Mediterranean tephrostratigraphy, which is still poorly explored and exploited.
Published: 2019

48. Glacial-interglacial dust and export production records from the Southern Indian Ocean

Author: H. Eri Amsler, Alexandra Auderset, Simone Moretti, Samuel L Jaccard, James Gilgannon, Xavier Crosta, Lena M Thöle, Elisabeth Michel, Alfredo Martínez-García, Alain Mazaud, Joerg Lippold, Hendrik Vogel, Oeschger Centre for Climate Change Research (OCCR), University of Bern, Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Climat et Magnétisme (CLIMAG), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Marine isotope stage, Polar front, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Iron fertilization, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, Oceanography, Ice core, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Interglacial, Earth and Planetary Sciences (miscellaneous), Ice age, Upwelling, 14. Life underwater, Glacial period, Geology, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: We present 230Th-normalized dust and export production fluxes for two contrasted marine sediment cores spanning the Antarctic Polar Front, close to the Kerguelen Plateau in the Southern Indian Ocean, covering the last glacial cycle. We report glacial lithogenic fluxes comparable to the South Atlantic and higher than in the South Pacific sectors of the Southern Ocean. Structural and temporal discrepancies with dust reconstructions from Antarctic ice cores and the Atlantic and Pacific sectors of the Subantarctic Zone (SAZ) point towards Southern Africa and/or the Kerguelen Plateau as an additional source of lithogenic material to the Southern Indian Ocean during the last ice age. In the SAZ, export production proxies respond to iron (Fe) fertilization with total organic carbon (TOC) fluxes as high as those previously reported from the Atlantic sector of the Southern Ocean. However, the correlation between export production and dust proxies is weaker than in the other sectors, and shows a muted response of export production during peak glacials. We hypothesize that this muted response may be related to macronutrient (co-)limitation imposed on phytoplankton growth possibly induced by a northward displacement of wind-driven upwelling and/or the polar frontal system during peak glacials. The Antarctic Zone (AZ) record depicts the typical pattern of enhanced export production during interglacials and comparatively low productivity during glacials suggesting a decrease in the supply of macronutrients to the AZ surface during ice ages compared to warm periods, as previously proposed. However, a muted response of opal fluxes during marine isotope stage (MIS) 5e argues for a southward migration of the frontal system during warmer MIS 5e, possibly causing silicic acid (co-)limitation at this site. These results illustrate the important role of Fe fertilization and changes in wind-driven upwelling intensities in modulating the strength and efficiency of the biological carbon pump in the Southern Ocean, but also highlight the potential role of frontal movements in explaining export production variability at sites located close to the Antarctic Circumpolar Current (ACC) fronts. Overall, our new datasets provide new insights on the regional differences in dust and export production patterns that need to be considered in order to evaluate the efficiency of carbon sequestration in the different sectors of the Southern Ocean during ice ages.
Published: 2019

49. Atmosphere‐Ocean CO2 Exchange Across the Last Deglaciation from the Boron Isotope Proxy

Author: James W. B. Rae, Helen L. Neil, Lowell D. Stott, Richard B. Coffin, Jun Shao, Ingo Pecher, William R Gray, Bryan Davy, Rosanna Greenop, University of Southern California (USC), School of Earth and Environmental Sciences [University St Andrews], University of St Andrews [Scotland], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), School of Environment [Auckland, New Zealand], University of Auckland [Auckland], National Institute of Water and Atmospheric Research [Auckland] (NIWA), Texas A&M University [Corpus Christi], GNS Science [Lower Hutt], GNS Science, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), NERC, University of St Andrews. School of Earth & Environmental Sciences, and University of St Andrews. St Andrews Isotope Geochemistry
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, GE, 010504 meteorology & atmospheric sciences, NDAS, Paleontology, Isotopes of boron, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Proxy (climate), 13. Climate action, Paleoceanography, Paleoclimatology, Deglaciation, SDG 13 - Climate Action, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Co2 exchange, Geology, 0105 earth and related environmental sciences, GE Environmental Sciences, SDG 15 - Life on Land
Abstract: J. Shao and L.D. Stott were supported by an NSF grant (MG&G 1558990). W. R. Gray and R. Greenop were supported by NERC grants NE/N011716/1 and NE/N011716/1 to J.W.B. Rae. I. Pecher, H.L. Neil, and B. Davy were supported by RSNZ Marsden Fund grant UOA1022. R. Coffin was supported by a DOE-NETL contract to NRL subcontract to TAMUCC (#601970). Identifying processes within the Earth System that have modulated atmospheric pCO2 during each glacial cycle of the late Pleistocene stands as one of the grand challenges in climate science. The growing array of surface ocean pH estimates from the boron isotope proxy across the last glacial termination may reveal regions of the ocean that influenced the timing and magnitude of pCO2 rise. Here we present two new boron isotope records from the subtropical‐subpolar transition zone of the Southwest Pacific that span the last 20 kyr, as well as new radiocarbon data from the same cores. The new data suggest this region was a source of carbon to the atmosphere rather than a moderate sink as it is today. Significantly higher outgassing is observed between ~16.5‐14 kyrBP, associated with increasing δ13C and [CO3]2‐ at depth, suggesting loss of carbon from the intermediate ocean to the atmosphere. We use these new boron isotope records together with existing records to build a composite pH/pCO2 curve for the surface oceans. pH disequilibrium/CO2 outgassing was widespread throughout the last deglaciation, likely explained by upwelling of CO2 from the deep/intermediate ocean. During the Holocene, a smaller outgassing peak is observed at a time of relatively stable atmospheric CO2, which may be explained by regrowth of the terrestrial biosphere countering ocean CO2 release. Our stack is likely biased toward upwelling/CO2 source regions. Nevertheless, the composite pCO2 curve provides robust evidence that various parts of the ocean were releasing CO2 to the atmosphere over the last 25 kyr. Publisher PDF
Published: 2019

50. Variability of the Indonesian Throughflow in the Makassar Strait over the Last 30 ka

Author: Weijia Fan, Haowen Dang, Zhihui Chu, Zhimin Jian, Xiqiu Han, Yue Wang, Yeping Bian, Franck Bassinot, State Oceanic Administration (SOA), Tongji University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Throughflow, Multidisciplinary, 010504 meteorology & atmospheric sciences, lcsh:R, lcsh:Medicine, Hiatus, 010502 geochemistry & geophysics, 01 natural sciences, Western Hemisphere Warm Pool, Article, Oceanography, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Outflow, lcsh:Q, 14. Life underwater, Glacial period, Ocean heat content, lcsh:Science, Thermocline, Geology, Holocene, 0105 earth and related environmental sciences
Abstract: The hydrological characteristics, including temperatures and salinities, of the upper water over the last 30 ka from two sites connected by the Indonesian Throughflow (ITF) across the Makassar Strait are reconstructed and compared. The thermocline hydrological gradient in the strait was larger during 13.4~19 ka BP and 24.2~27 ka BP than that in the Holocene. The weakened ITF during those periods in the last glacial period, corresponding to the decreased trade wind stress under an El Niño-like climate mean state, likely accounts for the increased thermocline gradient. The thermocline water temperature variabilities of the two sites, in particular the highest peaks at ~7 ka BP, are different from the records of the open western Pacific. Reoccurrence of the South China Sea Throughflow and thus a decreased surface throughflow along the Makassar Strait perhaps led to a warmer peak of thermocline temperature at ~7 ka BP than at ~11 ka BP.
Published: 2018

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422 results on '"Paléocéanographie (PALEOCEAN)"'

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