Author: "Marine Geology" / Topic: 010504 meteorology & atmospheric sciences - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Marine Geology"' showing total 94 results

Start Over Author "Marine Geology" Topic 010504 meteorology & atmospheric sciences

94 results on '"Marine Geology"'

1. Geochemical focusing and sequestration of manganese during eutrophication of Lake Stechlin (NE Germany)

Author: Scholtysik, Grzegorz, Dellwig, Olaf, Roeser, Patricia, Arz, Helge Wolfgang, Casper, Peter, Herzog, Christiane, Goldhammer, Tobias, Hupfer, Michael, Department of Chemical Analytics and Biogeochemistry, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany, Department of Marine Geology, Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Rostock, Germany, and Department Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
Subjects: Rhodochrosite, 010504 meteorology & atmospheric sciences, Lacustrine sediments, chemistry.chemical_element, Manganese, 010502 geochemistry & geophysics, 01 natural sciences, Diagenesis, Water column, Environmental Chemistry, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Varves, Authigenic, Eutrophication, Anoxic waters, chemistry, Environmental chemistry, ddc:551.9, Environmental science, Sedimentary rock, Geochemical focusing
Abstract: Significant sedimentation of manganese (Mn) in form of manganese oxides (MnOx) and the subsequent formation of authigenic calcium-rich rhodochrosite (Mn(Ca)CO3) were observed in the seasonally stratified hard water Lake Stechlin in north-eastern Germany. This manganese enrichment was assumed to be associated with recent eutrophication of the formerly oligotrophic lake. The mechanisms and processes involved were examined by analysing: (i) short sediment cores obtained from seven locations along a depth transect ranging from 69.5 m (the deepest point) to 38 m; (ii) sediment traps located at 20 m and 60 m water depths; (iii) water column profiles; and (iv) porewater profiles at 69.5 m and 58 m depths. Sedimentary Mn enrichment was observed at water depths below 56 m and increased to more than 25 wt% at the deepest site. Between 2010 and 2017, Mn accumulation at the deepest site was 815 g Mn m−2. Transfer of Mn from the shallower towards the deepest parts of the lake was initiated by reductive dissolution of MnOx and diffusion of dissolved Mn from the sediment to the overlying water column. Manganese was then dissipated via turbulent mixing and subsequently oxidised to MnOx before being transported towards the deepest zone. Transformation of the redeposited MnOx to Mn(Ca)CO3 favoured the final burial of Mn. We show that eutrophication and the areal spreading of anoxic conditions may intensify diagenetic processes and cause the spatial redistribution of Mn as well as its effective burial. Contrary to many previous findings, we show that increases of Mn and Mn/Fe can also be used as indicators for increasing anoxic conditions in previously oligotrophic lakes., Leibniz-Gemeinschaft http://dx.doi.org/10.13039/501100001664, Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB) im Forschungsverbund Berlin e.V. (3473)
Published: 2020
Full Text: View/download PDF

2. Enhanced terrigenous organic matter input and productivity on the western margin of the Western Pacific Warm Pool during the Quaternary sea-level lowstands: Forcing mechanisms and implications for the global carbon cycle

Author: Tiegang Li, Rongtao Sun, Shiming Wan, Fengming Chang, Dhongil Lim, Zhaojie Yu, Peter D. Clift, Zhaokai Xu, Christophe Colin, 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), Louisiana State University (LSU), CAS Institute of Oceanology (IOCAS), Chinese Academy of Sciences [Beijing] (CAS), Shandong Vocational University of Science and Technology (SDVUST), CAS Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, and South Sea Research Institute, Korea Institute of Ocean Science & Technology, Geoje 53201
Subjects: 010506 paleontology, Archeology, Global and Planetary Change, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental shelf, Terrigenous sediment, Biological pump, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 01 natural sciences, Western Hemisphere Warm Pool, Carbon cycle, Bottom water, Oceanography, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental science, 14. Life underwater, Quaternary, Ecology, Evolution, Behavior and Systematics, Sea level, 0105 earth and related environmental sciences
Abstract: International audience; Changes in terrigenous organic matter (OM) input, productivity and the associated bottom-water redox conditions, together with forcing mechanisms and global carbon cycle implications of such variations, on the western margin of the Western Pacific Warm Pool (WPWP) during the Quaternary remain controversial. In this study, we reconstructed the hydrological dynamics, terrigenous OM input, productivity, and deep-sea redox conditions using one core from the continental slope of the Philippine Sea. The new data were integrated with published proxies from the same core and two additional cores from the abyssal Philippine Sea. The results exhibited noticeable variations in the abovementioned indicators, in correspondence to changes in the supply of terrigenous material. The continental slope deposition featured signals of strong physical erosion and chemical weathering of unconsolidated sediments on the exposed continental shelf during the Quaternary sea-level lowstands, which significantly contributed to increased terrigenous OM input and productivity and, in turn, decreased bottom-water oxygenation and atmospheric CO2 concentrations. In the abyssal Philippine Sea, increased Asian dust-driven OM input and productivity also acted as a sink of atmospheric CO2 during sea-level lowstands. Analysis of the data suggested that the enhanced terrigenous OM input and biological pump and thus the decreased dissolved oxygen level of the bottom water on the western margin of the WPWP played important roles in modifying the global carbon cycle during sea-level lowstands. In contrast, the influence of hydrological dynamics on terrigenous OM input, productivity, and redox conditions therein during the Quaternary was limited.
Published: 2020
Full Text: View/download PDF

3. The Messinian erosional surface and early Pliocene reflooding in the Alboran Sea: New insights from the Boudinar basin, Morocco

Author: Johanna Lofi, Frédéric Quillévéré, Abdelkhalak Ben Moussa, Michel Séranne, Mohammed Achalhi, Gilles Merzeraud, Ali Azdimousa, Pierre Moisette, Jean-Jacques Cornée, Philippe Münch, Mihaela Carmen Melinte-Dobrinescu, Christian Chaix, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université Mohamed 1er, faculté des sciences, Oujda, 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), National Institute of Marine Geology and Geo-ecology (GeoEcoMar ), Histoire naturelle de l'Homme préhistorique (HNHP), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD), Université Abdelmalek Essaâdi (UAE), Université Mohammed Premier [Oujda], 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), National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Stratigraphy, Alluvial fan, Geology, Messinian Salinity Crisis, Late Miocene, 010502 geochemistry & geophysics, Neogene, 01 natural sciences, Onlap, Alboran Sea, Morocco, Zanclean flooding, Paleontology, Basement (geology), Subaerial, Marl, Boudinar basin, 14. Life underwater, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, 0105 earth and related environmental sciences, Marine transgression
Abstract: International audience; New investigations in the Neogene Boudinar basin (Morocco) provide new information about the Messinian Salinity Crisis (MSC) and Zanclean reflooding in the southern part of the Alboran realm (westernmost Mediterranean). Based on a new field, sedimentological and palaeontological analyses, the age and the geometry of both the Messinian erosional surface (MES) and the overlying deposits have been determined. The MES is of late Messinian age and was emplaced in subaerial settings. In the Boudinar basin, a maximum of 200 m of Miocene sediments was eroded, including late Messinian gypsum blocks. The original geometry of the MES is preserved only when it is overlain by late Messinian continental deposits, conglomeratic alluvial fans or lacustrine marly sediments. These sediments are interpreted as indicators of the sea-level fall during the MSC. Elsewhere in the basin, the contact between late Messinian and early Pliocene deposits is a low-angle dipping, smooth surface that corresponds to the early Pliocene transgression surface that subsequently re-shaped the regressive MES. The early Pliocene deposits are characterized by: (i) their onlap onto either the basement of the Rif chain or the late Miocene deposits; (ii) lagoonal deposits at the base to offshore marls and sands at the top (earliest Pliocene; 5.33–5.04 Ma interval; foraminifer zone PL1); (iii) marine recovery occurring in the 5.32–5.26 Ma interval; and (iv) the change from lagoonal to offshore environments occurring within deposits tens of metres thick. This information indicates that at least the end of the reflooding period was progressive, not catastrophic as previously thought.
Published: 2016
Full Text: View/download PDF

4. Increased seasonality and aridity drove the C4 plant expansion in Central Asia since the Miocene–Pliocene boundary

Author: Christophe Colin, Wenqiang Pei, Shiming Wan, Xuefa Shi, Xingyan Shen, Yang Tan, Xuejun Jiang, Ryuji Tada, Anchun Li, Key Laboratory of Marine Geology and Environment [China, Institute of Oceanology [China], University of Chinese Academy of Sciences [Beijing] (UCAS), Qingdao National Laboratory for Marine Science and Technology, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Science [Tokyo], The University of Tokyo (UTokyo), SOA, Inst Oceanog 1, Key Lab Marine Sedimentol & Environm Geol, Qingdao, Peoples R China., Institut des Systèmes Intelligents et de Robotique (ISIR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Qingdao Institute of Marine Geology, China Geological Survey, Qingdao 266071, China, Université Paris Diderot - Paris 7 (UPD7), State Key Laboratory of Marine Geology [Shanghai], Tongji University, Graduate School of Science [Tokyo], and The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo)
Subjects: Biomass (ecology), 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Westerlies, Vegetation, 15. Life on land, Seasonality, Late Miocene, 010502 geochemistry & geophysics, medicine.disease, 01 natural sciences, Arid, Geophysics, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Isotopes of carbon, [SDU]Sciences of the Universe [physics], Earth and Planetary Sciences (miscellaneous), medicine, Physical geography, Precipitation, Geology, 0105 earth and related environmental sciences
Abstract: Continuous and high-resolution records of the content, mass accumulation rate (MAR) and δ 13 C values of black carbon obtained from Integrated Ocean Drilling Program (IODP) Site U1430 in the southwestern Japan Sea have been established and combined with previous results obtained from Central Asia. The main objective of this work is to reconstruct the historical changes in vegetation types (C3–C4), and to constrain the driving force of C4 plant expansion over the last 13 Ma. The stable carbon isotope value of black carbon ( δ 13 CBC) shows a major shift since the Miocene–Pliocene boundary (∼5.3 Ma), suggesting significant expansion of C4 plants in broad areas of Central Asia, including the inland basins of northwestern China and the Loess Plateau. However, a decline in the content and MAR of black carbon reveals the absence of any link between fire and C4 plant expansion in Central Asia, due to the dramatic decrease in biomass under a drying regime. On a global scale, asynchronous expansion of C4 plants suggests that regional hydroclimatic change, rather than decline in CO2 concentration, was the most important factor to influence C4 expansion. We propose that the increased seasonality and the enhanced long-term aridity driven by the concurrent decline in winter westerly vapor, and increase in East Asian summer monsoon precipitation, were the main driving forces of C4 plant expansion in broad areas of Central Asia. Variations in winter westerly moisture have played a significant role in changes of regional climate and vegetation in Central Asia since the late Miocene.
Published: 2018
Full Text: View/download PDF

5. Antarctic Intermediate Water penetration into the Northern Indian Ocean during the last deglaciation

Author: Christophe Colin, Arnaud Dapoigny, Zhaojie Yu, F. Bassinot, Shiming Wan, Qiong Wu, Laure Meynadier, Ruifang Ma, Nejib Kallel, Sophie Sépulcre, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Marine Geology and Environment [China, Institute of Oceanology [China], Center for Ocean Mega-Science, Chinese Academy of Sciences, 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), College of Oceanography, Hohai University, Unité GEOGLOB, Faculté des Sciences de Sfax, Université de Sfax - University of Sfax-Université de Sfax - University of Sfax, 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), Géochrononologie Traceurs Archéométrie (GEOTRAC), 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), This work was supported by the National Natural Science Foundation of China (41622603 and 41576034), National Programme on Global Change and Air–Sea Interaction (GASI-GEOGE-03), Innovation Project (2016ASKJ13) and Aoshan Talents programme (2017ASTCP-ES01) of Qingdao National Laboratory for Marine Science and Technology and CAS Interdisciplinary Innovation Team, Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy of Sciences (No. MGE2018KG01). Z. Yu acknowledges the China Scholarship Council for providing funding for his study in France. This study was supported by the Labex L-IPSL and the MONOPOL projects, which are funded by the ANR (grant nos. ANR-10-LABX-0018 and ANR 2011 Blanc SIMI 5-6 024 04), ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), ANR-11-BS56-0024,MONOPOL,Paléo-variabilité de la mousson indienne(2011), 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), 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), 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-10-LABX-0018/10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010)
Subjects: 010504 meteorology & atmospheric sciences, Climate change, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Panoply, law.invention, Foraminifera, Geochemistry and Petrology, law, Earth and Planetary Sciences (miscellaneous), Deglaciation, 14. Life underwater, Radiocarbon dating, 0105 earth and related environmental sciences, Carbon dioxide in Earth's atmosphere, Antarctic Intermediate Water, biology, Northern Hemisphere, biology.organism_classification, Geophysics, Oceanography, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Upwelling, Geology
Abstract: The two-stage increase in atmospheric carbon dioxide (CO2), and the associated decrease in radiocarbon (14C) during the last deglaciation, are thought to have been linked to enhanced Southern Ocean upwelling and the rapid release of sequestered 14C-depleted CO2. Antarctic Intermediate Water (AAIW), originating from the Southern Ocean, reflects variations in the Southern Ocean and, crucially, mirrors the chemical signature of upwelling deep water. However, the penetration of AAIW into the Northern Indian Ocean and its relationship with deglacial climate changes have not been thoroughly elucidated to date. Here, we present the neodymium isotopic composition ( e Nd ) of mixed planktonic foraminifera from core MD77-176 from an intermediate depth in the Northern Indian Ocean to reconstruct the past evolution of intermediate water during deglaciation. The e Nd record in the Northern Indian Ocean displays two pulse-like shifts towards more radiogenic Southern Ocean values during the deglaciation, and these shifts coincide with excursions in Δ 14 C and e Nd records in the Pacific and Atlantic Oceans. These results suggest invasion of AAIW into the Northern Hemisphere oceans associated with enhanced Southern Ocean ventilation during deglaciation. Our new e Nd record strongly supports the close linkage of AAIW propagation and atmospheric CO2 rise through Southern Ocean ventilation during deglaciation.
Published: 2018
Full Text: View/download PDF

6. Are Paleomagnetic Records From U-Channels Appropriate for Studies of Reversals and Excursions?

Author: Édouard G. H. Philippe, Jean-Pierre Valet, Guillaume St-Onge, Anojh Thevarasan, Institut des Sciences de la MER de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), ERCAdvanced grant GA 339899-EDIFICEunder the ERC’s 7th FrameworkProgram (FP7-IDEAS-ERC) and by anNSERC Discovery Grant., 2Institut des sciences de la mer de Rimouski, Canada Research Chair in Marine Geology and GEOTOP, Université du Québec à Rimouski, Rimouski, Quebec, Canada, 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), and Institut des sciences de la mer de Rimouski, Canada Research Chair in Marine Geology and GEOTOP, Université du Québec à Rimouski, Rimouski, Quebec, Canada
Subjects: Paleomagnetism, 010504 meteorology & atmospheric sciences, geomagnetic excursions, paleomagnetic measurements, Magnetometer, Polarity (physics), Rapid Time Variations, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, geomagnetic reversals, 010502 geochemistry & geophysics, 01 natural sciences, Geomagnetic reversal, law.invention, Geomagnetism and Paleomagnetism, Geomagnetic Induction, Geochemistry and Petrology, law, Instruments and Techniques, Magnetism in the Geosciences ‐ Advances and Perspectives, Research Articles, 0105 earth and related environmental sciences, Geomagnetic secular variation, Excursion, Sampling (statistics), Geodesy, Geophysics, Earth's magnetic field, 13. Climate action, [SDU]Sciences of the Universe [physics], Geology, Research Article
Abstract: Sampling of sediment cores using plastic U‐channels has made possible the acquisition of detailed records of paleomagnetic secular variation, geomagnetic polarity, environmental magnetic studies, and relative paleointensity over the past several million years. U‐channel measurements provide the great advantage of rapid measurements of long sediment cores, but the signal resolution is attenuated by the response function of the magnetometer sensors, which therefore restrains the recovery of rapid and large‐amplitude field changes. Here we focus on the suitability of the dynamics of reversals and excursions derived from U‐channel measurements. We compare successive individual paleomagnetic directions of 1.5 cm × 1.5 cm × 1.5 cm cubic discrete samples with those of a 1.5‐m equivalent U‐channel sample train obtained by placing the samples adjacent to each other. We use varying excursion and transition lengths and generate transitional directions that resemble those of the most detailed paleomagnetic records. Excursions with opposite polarity directions recorded over less than 7.5 cm are barely detected in U‐channel measurements. Regarding reversals, U‐channel measurements smooth the signal of low‐resolution records and generate artificial transitional directions. Despite producing misleading similarities with the overall structure of transition records, longer transitional intervals fail also to reproduce the complexity of field changes. Finally, we test the convolution of magnetization by different response functions. The simulation reveals that even small response function changes can generate significant differences in results., Key Points U‐channel measurements fail to detect rapid excursions, except in the presence of high deposition ratesU‐channel fails to duplicate the original features of the field changes during polarity transitionsDiscrete samples of small size are thus required to fully reconstruct the detailed dynamics of reversals and excursions
Published: 2018
Full Text: View/download PDF

7. Crustal strain in the Marmara pull-apart region associated with the propagation process of the North Anatolian Fault

Author: Mihaela Carmen Melinte-Dobrinescu, Cagil Karakas, Roland Armijo, Robin Lacassin, Jean-Pierre Suc, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-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), National Institute of Marine Geology and Geo-ecology (GeoEcoMar ), 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), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), and Earth Observatory of Singapore
Subjects: bepress|Physical Sciences and Mathematics, Dardanelles, 010504 meteorology & atmospheric sciences, bepress|Physical Sciences and Mathematics|Earth Sciences|Tectonics and Structure, Ganos-Gelibolu Fold, North Anatolian Fault, bepress|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Stratigraphy, Fault (geology), Late Miocene, Messinian Salinity Crisis, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Deposition (geology), crustal shortening, Paleontology, Geochemistry and Petrology, Lithosphere, continental lithosphere, structural unconformity, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geology, bepress|Physical Sciences and Mathematics|Earth Sciences|Geology, Anticline, fault propagation, bepress|Physical Sciences and Mathematics|Earth Sciences|Stratigraphy, EarthArXiv|Physical Sciences and Mathematics, Tectonics, Geophysics, 13. Climate action, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Tectonics and Structure, Sedimentary rock, Geology
Abstract: Propagation processes of plate‐scale faults through continental lithosphere are poorly documented. The North Anatolian Fault (NAF) is a continental right‐lateral transform with striking evidence for propagation processes in the Marmara Sea pull‐apart region. Earlier work (Armijo et al., 1999, https://doi-org.ezlibproxy1.ntu.edu.sg/10.1130/0091‐7613(1999)0272.3.CO;2) suggests that in the Dardanelles, where the principal, northern branch of that fault (NNAF) enters into the Aegean: (1) a fold‐thrust system has progressively developed above the NNAF fault tip, at the WSW corner of the Marmara Sea pull‐apart. The main anticline formed there was sheared and its SW half laterally offset by ~70 km to the SW; (2) the timing of structure development appears correlated with sea level changes associated with the Messinian Salinity Crisis. Our new description of the Dardanelles (or Ganos‐Gelibolu) fold‐thrust system is based on structural mapping, field observations, and calcareous nannoplankton analyses to date key sedimentary units. Our results provide tight constraints on the main pulse of folding associated with propagation of the tip of the NNAF: it took place in the late Miocene to earliest Pliocene (5.60 to 5.04 Ma), before deposition of undeformed Pliocene marine sediments. The folding is mostly coeval with the Messinian Salinity Crisis and accommodated several kilometers of shortening at the fault tip. After full propagation of the NNAF up to the surface, the folded structure was sheared and right laterally offset, with an average 14 mm/year of slip rate during the past ~5 Myrs. A reconstruction of tectonic evolution suggests a flower structure nucleating and taking root at the tip of the fault. Published version
Published: 2018
Full Text: View/download PDF

8. ENSO-Like Modulated Tropical Pacific Climate Changes Since 2.36 Myr and Its Implication for the Middle Pleistocene Transition

Author: Zhaojie Yu, Shiming Wan, Tiegang Li, Hanjie Sun, Debo Zhao, Jie Huang, Christophe Colin, Zhaokai Xu, Lina Song, Anchun Li, Institute of Oceanology [China], Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China, Université Paris Diderot - Paris 7 (UPD7), Key Laboratory of Marine Geology and Environment [China, State Key Laboratory of Marine Geology [Shanghai], and Tongji University
Subjects: Early Pleistocene, 010504 meteorology & atmospheric sciences, Pleistocene, Middle Pleistocene Transition, Climate change, West Philippine Sea, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Geochemistry and Petrology, ENSO‐like system, 14. Life underwater, ENSO-like system, 0105 earth and related environmental sciences, grain size, myr, East Asian monsoon precipitation, Sea surface temperature, Geophysics, Oceanography, 13. Climate action, [SDU]Sciences of the Universe [physics], Upwelling, Walker circulation, Quaternary, Geology
Abstract: International audience; El Niño/Southern Oscillation (ENSO) activity and the Pacific Walker Circulation are controlled by the zonal sea surface temperature (SST) gradient between the western and Eastern Equatorial Pacific (EEP) and the corresponding barometric difference. Variations in the zonal SST gradient since the early Pleistocene have primarily been triggered by changes in the SST in the Eastern Equatorial Pacific. However, the response of the ENSO‐like long‐term state to the cooling of the EEP and its coupling role with tropical Pacific climate changes are still not well established. Here we present a high‐resolution grain‐size record spanning the last 2.36 Myr, obtained from marine core sediment located in the West Philippine Sea in order to decipher the tropical pacific climate changes and reveal its controlling mechanism. By combining our data with other long‐term climatic records from the Equatorial Pacific, we demonstrate that the cooling of SST and enhanced upwelling in the EEP resulted in the development of the Walker Circulation and increased monsoon precipitation in Luzon from 2.2 to 1.6 Myr, from 1.2 to 0.8 Myr, and since 0.2 Myr ago. The progressive cooling of the high‐latitudes in the Quaternary may be responsible for our observation here. A newly identified 100 kyr dominant period between 2.2 and 1.6 Myr in the ENSO‐like modulated Pacific climate records indicates that the ENSO‐like system may play a key role in facilitating or responding to the global climate changes.
Published: 2018
Full Text: View/download PDF

9. First evidence of a mid-holocene earthquake-triggered megaturbidite south of the chile triple junction

Author: Catherine Kissel, Maarten Van Daele, Alvaro Tamayo Hernando, Ricardo De Pol-Holz, Sebastien Bertrand, Loic Piret, Snecma Propulsion Solide (SPS), SAFRAN Group, 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), Departamento de Oceanografía [Concepción], Universidad de Concepción [Chile], Renard Centre of Marine Geology (RCMG), Universiteit Gent, Snecma Propulsion Solide ( SPS ), 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 ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Renard Centre of Marine Geology ( RCMG ), 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), Universidad de Concepción - University of Concepcion [Chile], and Universiteit Gent = Ghent University (UGENT)
Subjects: [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, Earthquake, 010504 meteorology & atmospheric sciences, Stratigraphy, Glacial lake outburst flood, Outburst flood, 010502 geochemistry & geophysics, Turbidite, 01 natural sciences, law.invention, Sedimentary depositional environment, Paleontology, law, Patagonia, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Radiocarbon dating, Sedimentology, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Subduction, Triple junction, food and beverages, Geology, Sediment provenance
Abstract: Megaturbidites have been the focus of many paleoseismic and paleoenvironmental studies because they can provide evidence for catastrophic and/or hazardous events with potentially major environmental implications. During a recent research cruise in Baker Fjord, Chile (47°54′S–74°30′W), a megaturbidite was described between the Northern and Southern Patagonian Icefields. Here, we aim to determine the depositional processes of the megaturbidite and identify its origin. Based on the turbidite's location, a possible origin was the early Holocene drainage of paleo-lake General Carrera, which was recently proposed in the literature as having produced a Glacial Lake Outburst Flood (GLOF) that drained through Baker Fjord. Due to the fjord's location in a subduction zone, and close to the Chile Triple Junction, however, seismic activity must also be considered as a potential triggering mechanism. To achieve our goals, we undertook a multi-proxy analysis of sediment core MD07-3121, including sedimentology (grain size, loss-on-ignition, foraminifera counts), magnetic properties, bulk organic geochemistry, and radiocarbon dating, and we analysed bathymetric maps and sub-bottom profiles. Our grain-size results display a diagnostic fining upward trend and show evidence of seiching in the 733-cm-thick megaturbidite. The age of the event (5513–5211 cal yr BP) contradicts the hypothesis of an early Holocene GLOF origin. Bulk organic geochemical results indicate that the sediments that compose the turbidite are clearly of marine origin, which further goes against a GLOF origin. In addition, the megaturbidite is underlain by a 1136 cm thick mass transport deposit (MTD), also composed of marine sediments. According to the sub-bottom profiles, the MTD and the megaturbidite originate from the reworking of thick packages of sediment previously deposited on nearby sills and on the fjord's flanks. Furthermore, similar coeval deposits are found in an adjacent sub-basin. We therefore interpret these deposits to be triggered by an earthquake during the late mid-Holocene. While megathrust and intraslab earthquakes are possible in the region, we argue that a crustal earthquake is the most likely seismic trigger in the study area. This study reveals the first earthquake-triggered megaturbidite south of the Chile Triple Junction.
Published: 2018
Full Text: View/download PDF

10. Holocene Event Record of Aysén Fjord (Chilean Patagonia): An Interplay of Volcanic Eruptions and Crustal and Megathrust Earthquakes

Author: Maarten Van Daele, Giuseppe Siani, Galderic Lastras, Frank Lamy, Katleen Wils, Catherine Kissel, Renard Centre of Marine Geology (RCMG), Department of Geology, Ghent University, Ghent, Belgium, Renard Centre of Marine Geology (RCMG), Universiteit Gent, GRC Geociències Marines, Department of Earth and Ocean Dynamics, Universitat de Barcelona, Barcelona, Spain, 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), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University (UGENT), 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, seismic stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Paleoseismology, fjord, 010502 geochemistry & geophysics, Megathrust earthquake, 01 natural sciences, law.invention, Geochemistry and Petrology, law, Earth and Planetary Sciences (miscellaneous), Radiocarbon dating, Holocè, Chile, Holocene, 0105 earth and related environmental sciences, landslides, Paleosismologia, Geophysics, Seismic hazard, Stratigraphy, 13. Climate action, Space and Planetary Science, Esllavissades, [SDU]Sciences of the Universe [physics], Epicenter, Estratigrafia sísmica, Patagònia (Argentina i Xile), Patagonia (Argentina and Chile), Tephrochronology, paleoseismology, Seismology, Geology
Abstract: International audience; In the first months of 2007, the Aysén region in southern Chile was affected by a crustal seismic swarm. Its largest earthquake (M w 6.2) occurred in April and had its epicenter in Aysén Fjord. Seismic intensities became so high that hundreds of onshore mass movements were triggered, several of which entered into the fjord, resulting in mass transport deposits (MTDs) preserved at the fjord bottom. Here we present a Holocene record of paleo-earthquakes in the previously unstudied Patagonian fjordland based on MTD stratigraphy. High-resolution seismic data retrieved using two different seismic systems (sparker and TOPAS) reveal multiple older MTDs on different stratigraphic levels. Correlation of the seismic stratigraphy with sedimentological data obtained from a long Calypso core (MD07-3117) allows conclusion on the seismic origin of these deposits. Additionally, radiocarbon dating permits constructing an age model, validated by tephrochronology, providing an age for the different MTD levels. We thus present a highly detailed paleoseismological history of the Aysén region, including at least six major Holocene earthquakes, one of which is likely related to a known megathrust earthquake. Other earthquakes are related to activity of the Liquiñe-Ofqui Fault Zone (LOFZ), forming the main source of seismic hazard in the area. We can infer a general average recurrence time for LOFZ earthquakes of~2,100 years in the vicinity of Aysén Fjord with clustered events during the early and late Holocene. Finally, we argue that cascading events (causal link between volcanic and seismic events) may be a frequent phenomenon along the LOFZ.
Published: 2018
Full Text: View/download PDF

11. Distinct control mechanism of fine-grained sediments from Yellow River and Kyushu supply in the northern Okinawa Trough since the last glacial

Author: Hanchao Jiang, Yoshimi Kubota, Sidonie Révillon, Xuefa Shi, Xufeng Zheng, Zhaokai Xu, Ryuji Tada, Debo Zhao, Shiming Wan, Peter D. Clift, Zhaojie Yu, Samuel Toucanne, Anchun Li, Jie Huang, Institute of Oceanology [China], Qingdao National Laboratory for Marine Science and Technology, Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao, Peoples R China, 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), 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), IFREMER, Unite Rech Geosci Marines, Lab Geophys & Enregistrements Sedimentaires, Plouzane, France., Louisiana State University (LSU), Department of Earth and Planetary Science [Tokyo], The University of Tokyo (UTokyo), Laboratoire Géosciences Océan (LGO), 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), Natl Museum Nat & Sci, Dept Geol, Ibaraki, Japan., Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou, Guangdong, Peoples R China., Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), China Earthquake Adm, Inst Geol, State Key Lab Earthquake Dynam, Beijing, Peoples R China., Key Laboratory of Marine Geology and Environment [China, SOA, Inst Oceanog 1, Key Lab Marine Sedimentol & Environm Geol, Qingdao, Peoples R China., State Key Laboratory of Marine Geology [Shanghai], Tongji University, Université de Bretagne Sud (UBS)-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 de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Graduate School of Science [Tokyo], and The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo)
Subjects: Provenance, 010504 meteorology & atmospheric sciences, Tsushima Warm Current, Trough (geology), Fluvial, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Yellow River, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Okinawa Trough, Geochemistry and Petrology, River mouth, 14. Life underwater, Glacial period, 0105 earth and related environmental sciences, Kyushu Island, geography, geography.geographical_feature_category, clay-sized sediments, Sediment, Silicate, sea-level change, Geophysics, Oceanography, chemistry, 13. Climate action, [SDU]Sciences of the Universe [physics], Kuroshio Current, Sediment transport, Geology
Abstract: High-resolution multi-proxy records, including clay minerals and Sr-Nd-Pb isotopes of the clay-sized silicate fraction of sediments from IODP Site U1429 in the northern Okinawa Trough, provide reliable evidence for distinct control mechanism on fine-grained sediments input from the Yellow River and the southern Japanese Islands to the northern Okinawa Trough since 34 ka BP. Provenance analysis indicates that the sediments were mainly derived from the Yellow River and the island of Kyushu. Since the last glacial, clay-sized sediments transported from the Yellow River to the study site were strongly influenced by sea-level fluctuation. During low sea-level stage (∼34‒14 ka BP), the paleo-Yellow River mouth was positioned closer to the northern Okinawa Trough, favoring large fluvial discharge or even direct input of detrital sediments, which resulted about four times more flux of clay-sized sediments supply to the study area as during the relatively high sea-level stage (∼14‒0 ka BP). The input of Kyushu-derived clay-sized sediments to the study site was mainly controlled by the Kuroshio Current and Tsushima Warm Current intensity, with increased input in phase with weakened Kuroshio Current/Tsushima Warm Current. Our study suggests that the Kuroshio Current was very likely flowed into the Okinawa Trough and thus influenced the fine-grained sediment transport in the area throughout the last glacial and deglacial. During ∼34‒11 ka BP, the Kyushu clay-sized sediment input was mainly controlled by the Kuroshio Current. Since ∼11 ka BP, the occurrence of Tsushima Warm Current became important in influencing the Kyushu fine-grained sediment input to the northern Okinawa Trough.
Published: 2017
Full Text: View/download PDF

12. Seismic stratigraphy of the late Quaternary sedimentary infill of Lac d'Armor (Kerguelen archipelago): a record of glacier retreat, sedimentary mass wasting and southern Westerly intensification

Author: Katrien Heirman, Fabien Arnaud, Marc De Batist, Jacques-Louis de Beaulieu, Renard Centre of Marine Geology, RCMG, Royal Belgian Institute of Natural Science, Geological Survey of Belgium, Renard Centre of Marine Geology (RCMG), Universiteit Gent = Ghent University [Belgium] (UGENT), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-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), and Environnements, Dynamiques et Territoires de Montagne (EDYTEM)
Subjects: 010504 meteorology & atmospheric sciences, Mass wasting, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Paleontology, Wind-driven currents, drift deposit, Deglaciation, lacustrine sedimentation, 14. Life underwater, Geomorphology, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Geology, Westerlies, Lacustrine sedimentation, Facies, Archipelago, wind-driven currents, Sedimentary rock, Quaternary, glacial sedimentation, Glacial sedimentation
Abstract: Lac d'Armor (49°27′S, 69°42′E) is a medium-sized, fjord-type lake located on the ‘Grande Terre’ island of the Kerguelen archipelago. A dense grid of high-resolution reflection seismic profiles was collected from this lake basin. The seismic stratigraphic facies reveal a last deglaciation to Holocene infill comparable to the seismic facies found in other glacigenic lakes all over the world. Remarkable features in the seismic stratigraphy are mounded structures found at the southern edge of both sub-basins. The sediment mounds can be interpreted as sediment drifts created by wind-induced bottom currents. The onset of the build-up of these drifts initiated at some point in the Holocene and indicates a strengthening of the southern Westerlies, which are currently the dominant winds on this island.
Published: 2012
Full Text: View/download PDF

13. Major and trace element distributions in manganese nodules and micronodules as well as abyssal clay from the Clarion-Clipperton abyssal plain, Northeast Pacific

Author: V. E. Alexe, O.G. Duliu, S.A. Szobotca, Jacques Moutte, Department of Atomic & Nuclear Physics, University of Bucharest (UniBuc), Geological Institute of Romania, Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Géochimie, environnement, écoulement, réacteurs industriels et cristallisation (GENERIC-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), (1) University of Bucharest, and National Institute for Marine Geology and Geoecology
Subjects: Nodule (geology), 010504 meteorology & atmospheric sciences, manganese micronodules, trace elements, Mineralogy, Environmental Science (miscellaneous), engineering.material, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, manganese nodules, Abyssal zone, hydrothermal origin, Earth and Planetary Sciences (miscellaneous), [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, 0105 earth and related environmental sciences, Basalt, geography, geography.geographical_feature_category, abyssal clay, Continental crust, major elements, ICP-AE spectrometry, Trace element, Abyssal plain, Sediment, Geotechnical Engineering and Engineering Geology, Igneous rock, Clarion-Clipperton abyssal plain, 13. Climate action, engineering, Geology
Abstract: International audience; The contents of seven major components (TiO2, Fe2O3, MgO, CaO, Na2O, K2O and P2O5) and 15 trace elements (Sc, V, Cr, Ni, Cu, Sr, Y, Zr, Ba, La, Ce, Nd, Eu, Yb and Th) were determined by ICP-AE spectrometry in 27 samples of manganese nodules, micronodules as well as abyssal clay collected by dredging from an area of nearly 1,9802 nautical miles in the central Clarion-Clipperton abyssal plain at a depth of about 4,500 m. Statistical analyses were used to compare among individual as well as pooled datasets, in addition to different indicators such as La/Th, Ni/Cu and LREE/HREE ratios for the Clarion-Clipperton samples, as well as between these and corresponding values for the upper continental crust (UCC), North America Shale Composite (NASC), and igneous Indian and Pacific Mid-Ocean Ridge Basalts (MORBs). The results show significant correlations between major components in the Clarion-Clipperton samples and Pacific Ocean MORB, whereas trace elements (excepting Ni and Cu) correlate better with the UCC and NASC. There is also depletion in LREEs, together with a Ce negative anomaly for all Clarion-Clipperton samples. The nodule, micronodule and abyssal clay datasets each reveal typical clusters of components such as P2O5 and Y, La, Nd, Eu, Tb, or Ni and Cu. Compared to abyssal clay, the nodule as well as micronodules show significant enrichment in Ni and Cu; nevertheless, an essentially constant Ni/Cu ratio indicates that all samples come from the sediment surface. The distributions of major components as well as trace elements for the Clarion-Clipperton samples present, to different degrees, characteristics common to both the upper continental crust and Mid-Ocean Ridge Basalt, strongly implying a hydrothermal origin, most probably from East Pacific Rise material transported by the Pacific North Equatorial Current.
Published: 2008
Full Text: View/download PDF

14. Trace element contamination in the arms of the Danube Delta (Romania/Ukraine): Current state of knowledge and future needs

Author: Gheorghe Oaie, Janusz Dominik, Adrian Stanica, Davide A.L. Vignati, Régis Céréghino, Dan Secrieru, Nikolai A. Berlinsky, Stefan Szobotka, Yuliya I. Bogatova, Université de Genève (UNIGE), Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Terre et Environnement de Lorraine (OTELo), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), National Institute of Marine Geology and Geoecology (Romania), Research Center (RC) Noosphera (Ukraine), Istituto di Science Marine (ISMAR ), Consiglio Nazionale delle Ricerche (CNR), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), 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)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique - CNRS (FRANCE), Consiglio Nazionale delle Ricerche - CNR (ITALY), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de Genève (SWITZERLAND), National Institute of Marine Geology and geoecology - GeoEcomar (ROMANIA), Istituto di Science Marine - ISMAR (ITALY), Research Center (RC) Noosphera (UKRAINE), Université de Lorraine (FRANCE), Laboratoire Interdisciplinaire des Environnements Continentaux - LIEC (Vandoeuvre-Les-Nancy, France), Laboratoire Ecologie fonctionnelle et Environnement - EcoLab (Toulouse, France), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Université de Genève = University of Geneva (UNIGE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Terre et Environnement de Lorraine (OTELo), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-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)-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 Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: Delta, Geologic Sediments, Environmental Engineering, 010504 meteorology & atmospheric sciences, Drainage basin, 010501 environmental sciences, Management, Monitoring, Policy and Law, 01 natural sciences, Sediments, Contamination, Sediments Contamination, Environmental protection, Danube delta, ddc:550, Waste Management and Disposal, Baseline metals, 0105 earth and related environmental sciences, Self-Organizing Maps, Hydrology, Total organic carbon, Ecologie, Environnement, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, Trace elements, geography.geographical_feature_category, Trace element, Sediment, General Medicine, 6. Clean water, Current (stream), Environmental science, Danube Delta, Water Pollutants, Chemical, Environmental Monitoring
Abstract: Ecolab, Laboratoire Ecologie Fonctionnelle et Environnement, UMR 5245 UPS-CNRS-INPT, Universite de Toulouse, 118 route de Narbonne, 31062 Toulouse cedex 4, France This paper provides the first critical synopsis of contamination by selected trace elements in the whole Danube Delta (Romania/Ukraine) to: identify general patterns of contamination by trace elements across the Delta, provide recommendations to re fine existing monitoring networks and discuss the potential toxicity of trace elements in the whole Delta. Sediment samples were collected between 2004 and 2007 in the three main branches of the Delta (Chilia, Sulina and Sfantu Gheorghe) and in the secondary delta of the Chilia branch. Samples were analyzed for trace elements (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) and TiO 2, Fe 2O3, MnO, CaCO 3 and total organic carbon. Cluster analysis (CA) and Principal Component Analysis (PCA) showed that levels of Cd, Cu, Pb, and Zn were in fluenced by anthropogenic activities. At the opposite, concentrations of Cr and Ni largely originated from the weathering of rocks located in the Romanian part of the Danube catchment and naturally rich in these elements. Data analysis using Self- Organizing Maps con firmed the conclusions of CA/PCA and further detected that the contamination tended to be higher in the Chilia and Sulina arms than in the Sfantu Gheorghe arm. The potential ecological risks due to trace element contamination in the Danube Delta could be identi fied as moderate and localized, provided that the presence of the natural sources of Cr and Ni was properly considered. The available results suggest that monitoring sediment quality at the mouths of Sulina and Sfantu Gheorghe arms is probably enough to get a picture of the sediment quality along their entire lengths. However, a larger network of monitoring points is necessary in the Chilia and secondary Chilia delta to account for the presence of local point sources and for the more complex hydrodynamic of this part of the Danube Delta.
Published: 2013
Full Text: View/download PDF

15. A two-step process for the reflooding of the Mediterranean after the Messinian Salinity Crisis

Author: Ferran Estrada, Daniel Aslanian, Rolando Armijo, Jean-Loup Rubino, Gülsen Uçarkuş, Dragana Tomić, M. Namık Çağatay, Speranta-Maria Popescu, Nikola Dumurdžanov, Ziyadin Cakir, Jean-Pierre Brun, Georges Clauzon, Ivan Zagorchev, Estelle Leroux, Jean-Pierre Suc, Laurent Jolivet, Jean-Louis Olivet, François Bache, Vesna Lesić, Bertrand Meyer, Gwenaël Jouannic, Laurent Londeix, Mihaela Carmen Melinte-Dobrinescu, Marina Rabineau, Antonio Tadeu dos Reis, Ludovic Mocochain, Dimitrios Sokoutis, Istvan Csato, Christian Gorini, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), GNS Science [Lower Hutt], GNS Science, Institut de Physique du Globe de Paris (IPGP), 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), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-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 (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), National Institite of Marine Geology & Geoecology, National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), Instituto de Ciencias del Mar de Barcelona (ICM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), 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), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Departamento de Oceanografia Geologica, Universidade do Estado do Rio de Janeiro [Rio de Janeiro] (UERJ), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Ss. Cyril and Methodius University in Skopje (UKIM), Geological Institute of BAS, Bulgarian Academy of Sciences (BAS), Geolomagnetic Institute, ITU (GEOLOGY AND MINING DEPARTMENT), Istanbul Technical University (ITÜ), ISES, Vrije Universiteit Amsterdam [Amsterdam] (VU), Department of Geology, Collin Collège, Maden Fakültesi = Faculty of mines [Istanbul], Sytèmes Tectoniques, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-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 de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-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 de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), CNRS-INSU AMEDITER CNRS-INSU TerMex, ANR-06-BLAN-0156,EGEO,Rhéologie et déformation de la lithosphère égéenne(2006), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), 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), Unité de recherche Géosciences Marines (Ifremer) (GM), 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 d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Sts Cyril and Methodius University, Faculty of mining and geology, University of Belgrade [Belgrade]-University of Belgrade [Belgrade], Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - 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), National Institute of Marine Geology and Geo-ecology (GeoEcoMar ), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), 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)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Geological Institute, Istanbul Technical University, Systèmes Tectoniques, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), School of Mines and eurasia Institute of Earth Sciences, and Tectonics
Subjects: decic basin, 010504 meteorology & atmospheric sciences, Evaporite, Aardwetenschappen, [SDE.MCG]Environmental Sciences/Global Changes, northern apennines, Diachronous, Structural basin, sea level, 010502 geochemistry & geophysics, di tetto formations, 01 natural sciences, Mediterranean Basin, Paleontology, miocene pliocene boundary, Stratotype, Mediterranean sea, paleo environmental changes, earliest zanclean age, 14. Life underwater, SDG 14 - Life Below Water, reflooding, Sea level, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, desiccated deep basin, southern France, Geology, 6. Clean water, subsidence studies, Oceanography, 13. Climate action, Subaerial, section marche province, depositional environments
Abstract: Bache, François ... et. al.-- 29 pages, 22 figures, 1 table, additional supporting information may be found in the online version of this article: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2117.2011.00521.x/suppinfo, The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re-visited onshore data from Italy and Turkey that lead to a new concept of a two-step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600-900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub-basins led to diachronous events such as the so-called 'Lago Mare'.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two-step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies. © 2011 Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists, This work is a contribution to ANR ‘EGEO’ Project, to CNRS/INSU ‘Actions Marges’ Project (AMEDITER), and to ‘Bassins ne´oge`nes et manteau en Méditerranée’ (TerMEx CNRS/INSU)
Published: 2012
Full Text: View/download PDF

16. Magnetochronology of synorogenic Miocene foreland sediments in the Fars arc of the Zagros Folded Belt (SW Iran)

Author: E. Khademi, Jean-Pierre Suc, Jaume Vergés, Elisabet Beamud, Frédéric Mouthereau, Juan C. Larrasoaña, Mihaela Carmen Melinte-Dobrinescu, Sh. Khadivi, Olivier Lacombe, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), National Geoscience Databas of Iran, National Geoscience Database, Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Geological Survey of Iran, National Institute of Marine Geology and Geo-ecology, and National Institute for Marine Geology and Geo-ecology (GeoEcoMar )
Subjects: Sabkha, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Tectonics, Stratigraphy, Alluvium, Sedimentary rock, Syncline, Zagros fold and thrust belt, Foreland basin, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: The timing of deformation in the northern Zagros Folded Belt is poorly constrained because of the lack of an accurate absolute chronology of the syntectonic sedimentary sequences. The foreland basin infill in the northern part of the Fars arc is composed of supratidal sabkha deposits (Razak Fm), medium-grained deltaic deposits (Agha Jari Fm) and coarse conglomerates of nearshore fan delta deposits at the base (Bakhtyari Fm, Bk1) and continental alluvial deposits at the top of the section (Bakhtyari Fm, Bk2). A magnetostratigraphic study was carried out in a composite section spanning about 1300 m on the northern flank of the Chahar-Makan syncline. Magnetostratigraphic correlation of the Razak Fm with chron C6n yields an age of 19.7 Ma at the base of the composite section. The transition to Agha Jari Fm is correlated with chron C5Cn, yielding an age of 16.6 Ma. The transition to the conglomerates of the Bakhtyari Fm (Bk1) correlates with the chron C5AD at approximately 14.8 Ma, which is considerably older than previously thought. The base of the Bakhtyari Fm growth strata, and thus the beginning of the deformation in northern Fars, is dated at 14-15 Ma. The topmost preserved Bakhtyari Fm (Bk1) is folded and unconformably overlain by Bakhtyari Fm (Bk2) conglomerates. This indicates that tectonic deformation in northern Zagros was already underway in the Middle Miocene. © 2009 The Authors. Basin Research © 2009 Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.
Published: 2010
Full Text: View/download PDF

17. Flow and sediment processes in a cutoff meander of the Danube Delta during episodic flooding

Author: Laura Jugaru Tiron, Nicolae Panin, Philippe Dussouillez, Jérôme Le Coz, Guillaume Raccasi, Mireille Provansal, Guillaume Dramais, National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), Hydrologie-Hydraulique (UR HHLY), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), 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), National Institute of Marine Geology and Geo-ecology (GeoEcoMar ), 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), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-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)
Subjects: 010504 meteorology & atmospheric sciences, 0207 environmental engineering, 02 engineering and technology, DANUBE DELTA, SEDIMENT, FORMER MEANDER, 01 natural sciences, SEDIMENT FLUXES, MORPHOLOGIE FLUVIALE, Aggradation, RIVER MORPHODYNAMICS, 020701 environmental engineering, Sedimentary budget, Geomorphology, ACOUSTIC DOPPLER CURRENT PROFILER, Stream power, 0105 earth and related environmental sciences, Earth-Surface Processes, Bed material load, MEANDRE, MODELE NUMERIQUE, Sediment, Point bar, ACOUSTIC DOPPLER CURRENT PROFILER (ADCP), ST. GEORGE BRANCH, 6. Clean water, Flow velocity, [SDE]Environmental Sciences, Meander, HYDRODYNAMIQUE, CRUE, DANUBE COURS D'EAU, TRANSPORT SOLIDE, Geology
Abstract: [Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU; This article analyzes the water and suspended solid fluxes through a straightened meander of the southern branch of the Danube Delta (the St. George branch) during episodic flooding. The Mahmudia study site corresponds to a vast natural meander which was cut off in 19841988 by an artificial canal opened to shipping. The meander correction accelerated fluxes through the artificial canal and dramatically enhanced deposition in the former meander. After his formation, the cutoff meander acted as sediment storage locations, essentially removing channel and point bar sediments from the active sediment budget of the main channel. Increases in slope and stream power in reaches upstream and downstream have also occurred, but to a lesser degree. During the one-hundred-year recurrent flood in April 2006, bathymetry, flow velocity and discharge data were acquired across several sections of both natural and artificial channels with an acoustic Doppler current profiler (aDcp Workhorse Sentinel 600 kHz, Teledyne RDI) in order to investigate the distribution of the flow and sediment and his impact on sedimentation in a channelized reach and its adjacent cutoff. The contrasting hydro-sedimentary processes at work in both channels and bifurcation/ confluence nodal points are analyzed from the measured flux distribution, morphological profiles and velocity and concentration patterns. In the cutoff, a diminishing of the intensity of the flow velocity (c. 50%) and of the SSC was observed correlated with the aggradation of the river bed. In the bifurcation/confluence nodal points and in the artificial canal were observed the most intensive hydrodynamic activity (high flow velocity, SSC concentration, degradation of the river bad). Both the event-scale and long-term morphological trends of the alluvial system are discussed analyzing the boundary shear stress and SSC variability. Excess boundary shear stress in the sub-reaches directly affected by cutoffs resulted in scour that increased downstream bed material load. These high sediment loads play a key role in driving morphological adjustments towards equilibrium in the cutoff channel. The approach followed in this paper combines detailed episodic in-situ aDcp measurements and robust numerical 1D modeling in order to provide a practical comprehension of the relevant morphodynamical processes. The 1D model reproduces robustly the continuity of hydrodynamical variables along the streamwise axes of the two-channel network. The simulated are used in the paper for highlighting reachscale morphological processes, at both event and long-term scales.
Published: 2009
Full Text: View/download PDF

18. The Role of Fluid Seepage in the Erosion of Mesozoic Carbonate Escarpments

Author: Or M. Bialik, Aaron Micallef, Nader Saadatkhah, Charles K. Paull, Paull, Charles K., 3 Monterey Bay Aquarium Research Institute Moss Landing CA USA, Saadatkhah, Nader, 1 Helmholtz Centre for Ocean Research GEOMAR Kiel Germany, Bialik, Or, and 2 Department of Geosciences Marine Geology and Seafloor Surveying University of Malta Msida Malta
Subjects: 010504 meteorology & atmospheric sciences, Escarpment, 010502 geochemistry & geophysics, 01 natural sciences, Head (geology), chemistry.chemical_compound, Fluid-structure interaction, Marine geophysics, Carbonate minerals, Geomorphology, Joint (geology), 0105 earth and related environmental sciences, Earth-Surface Processes, Submarine topography, Canyon, geography, geography.geographical_feature_category, Bedrock, Sedimentology, 15. Life on land, Geophysics, chemistry, 13. Climate action, Subaerial, Erosion, Carbonate, Submarine geology, ddc:551.3, Geology
Abstract: Mesozoic submarine carbonate escarpments are erosional features that host box canyons, the formation of which had been attributed to seepage erosion in view of their similarity to subaerial box canyons. The latter had been cited as diagnostic of groundwater activity, although the efficacy of fluid seepage as an erosive agent in bedrock remains controversial. Here we use multibeam echosounder data from the Blake, Campeche, Malta and Florida Escarpments to demonstrate that box canyon formation is, in general, a significant process eroding carbonate escarpments. Numerical modeling based on parameters from the Florida Escarpment shows that box canyons can initiate and retrogressively evolve by fluid seeping via joints, which causes a reduction in rock strength due to fluid pressure and dissolution, resulting in periodic block failure at the canyon head. Box canyon elongation is promoted by an exponential distribution of joint density, an increase in joint density, joints oriented perpendicular and parallel to the escarpment, or an increase in the thickness of the flowing groundwater zone and slope gradient of the escarpment. The angularity of the canyon head decreases with a decrease in joint density and when joint density is uniform, whereas the canyon width is regulated by the extent of the joint set zone. Since the key factors contributing to box canyon formation along the Florida Escarpment appear to characterize the Blake, Campeche and Malta Escarpments, the groundwater model for box canyon formation should be applicable to these escarpments as well., Plain Language Summary: Submarine carbonate escarpments are cliffs of limestone and dolomite that form anomalously steep topography on the Earth's surface. Box canyons—wide canyons with steep walls and semi‐circular heads—are a common feature in carbonate escarpments and they have been associated with groundwater seepage. In this study, we use seafloor depth information from four carbonate escarpments to show that box canyon erosion is a key process driving their evolution. Numerical modeling, on the other hand, suggests that fluid seeping in conditions similar to those of the Florida Escarpment can result in box canyon formation via periodic failure of the canyon head. Since these conditions at the Florida Escarpment can also be found in other escarpments such as the Blake, Campeche and Malta Escarpments, box canyon formation by groundwater seepage is likely a widespread geological process. The location of box canyons may suggest where fluid is seeping along escarpments and where specialized biological communities may be located. Box canyon formation is unlikely to pose a risk to coastal communities and offshore infrastructure., Key Points: Box canyon formation is a significant erosive process across carbonate escarpments. Fluid seeping through joints can drive initiation and retrogressive evolution of box canyons via periodic block failure at the canyon head., EC, H2020, H2020 Priority Excellent Science, H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663, EC, H2020, H2020 Priority Excellent Science, Marie Skłodowska‐Curie Actions, EC, FP7, FP7 Marie Curie Actions (MCA), Fulbright Association (FULBRIGHT) http://dx.doi.org/10.13039/100010629, David and Lucile Packard Foundation (PF) http://dx.doi.org/10.13039/100000008
Published: 2021
Full Text: View/download PDF

19. Late Holocene Changes in Erosion Patterns in a Lacustrine Environment: Landscape Stabilization by Volcanic Activity Versus Human Activity

Author: Sabine Schmidt, Osamu Fujiwara, Jacqueline Vander Auwera, Aurélia Hubert-Ferrari, Yusuke Yokoyama, Gilles Lepoint, Marc De Batist, Shinya Yamamoto, Evelien Boes, Meriam El Ouahabi, Laura Lamair, Vanessa M.A. Heyvaert, Department of Geography, University of Liège, Clos Mercator 3, 4000 Liège, Belgium, Université de Liège, Graduate School of Information Systems, University of Electro-Communications [Tokyo] (UEC), 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), L.A. Géologie, Pétrologie et Géochimie, MARE Centre, Laboratory for Oceanology, Atmosphere and Ocean Research Institute [Kashiwa-shi] (AORI), The University of Tokyo (UTokyo), Renard Centre of Marine Geology, and RCMG
Subjects: geography, geography.geographical_feature_category, Vulcanian eruption, 010504 meteorology & atmospheric sciences, Geochemistry, Sediment, 15. Life on land, Sedimentation, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, Volcano, 13. Climate action, Geochemistry and Petrology, Erosion, Scoria, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Tephra, ComputingMilieux_MISCELLANEOUS, Holocene, Geology, 0105 earth and related environmental sciences
Abstract: The most recent eruption of Mount Fuji (Japan), the VEI 5 Hoei plinian eruption (CE 1707) heavily impacted Lake Yamanaka, a shallow lake located at the foot of Mount Fuji. Here we discuss the influence of the Hoei eruption on the lacustrine sedimentation of Lake Yamanaka using high-resolution geophysical and geochemical measurements on gravity cores. Hoei scoria fallout had two major impacts on Lake Yamanaka: (i) reduction of the sedimentation rate (from similar to 0.16 to similar to 0.09 cm/year) and (ii) the increase of in situ lake productivity. Sedimentation rates after the eruption were relatively low due to the thick scoria layer, trapping underlying sediments in the catchment. The lacustrine system took more than similar to 170 years to begin to recover from the Hoei eruption: most recently sedimentation recovery has been accelerated by changes in land use. Since the beginning of the twentieth century, vegetated strips delimited cultivated parcels, trapping sediment and minimizing anthropogenic impacts on the sedimentation rate. Over the last decade, the decline of agriculture and the increase of other human activities has led to an increase in the sedimentation rate (similar to 1 cm/year). This study highlights the effect of the grainsize of the volcanic ejecta on the sedimentation rate following a volcanic eruption. Coarse-grained tephra are difficult to erode. Therefore, their erosion and remobilization is largely limited to intense typhoons when porous scoria deposits are saturated by heavy rains. Moreover, this study suggests that recent anthropogenic modifications of the catchment had a greater impact on the sedimentation rate than the Hoei eruption.
Published: 2019
Full Text: View/download PDF

20. Lost islands in the northern Lesser Antilles: possible milestones in the Cenozoic dispersal of terrestrial organisms between South-America and the Greater Antilles

Author: Cornée, Jean-jacques, Münch, Philippe, Philippon, Mélody, Boudagher-fadel, Marcelle, Quillévéré, Frédéric, Melinte-dobrinescu, Mihaela, Lebrun, Jean-frédéric, Gay, Aurelien, Meyer, Solène, Montheil, Lény, Lallemand, Serge, Marcaillou, Boris, Laurencin, Muriel, Legendre, Lucie, Garrocq, Clément, Boucard, Milton, Beslier, Marie-odile, Laigle, Mireille, Schenini, Laure, Fabre, Pierre-henri, Antoine, Pierre-olivier, Marivaux, Laurent, The Garanti And Antithesis Scientific Parties, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Université des Antilles (Pôle Guadeloupe), Université des Antilles (UA), Cardiac Unit, Institute of Child Health (UCL), University College of London [London] (UCL), 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), National Institute of Marine Geology and Geoecology (Romania), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), 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 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)-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, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), 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), 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]), 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: Lesser Antilles, 010504 meteorology & atmospheric sciences, Pleistocene, seismic stratigraphy, Cenozoic basins, palaeogeography, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Vertical motions, Biostratigraphy, Structural basin, 010502 geochemistry & geophysics, 01 natural sciences, Unconformity, Sedimentary depositional environment, Paleontology, 14. Life underwater, 0105 earth and related environmental sciences, vertical motions, Stratigraphy, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, General Earth and Planetary Sciences, Sedimentary rock, biostratigraphy, Cenozoic, Palaeogeography, Geology, Seismic stratigraphy
Abstract: Our study aims to reconstruct the palaeogeography of the northern part of the Lesser Antilles in order to analyse whether emerged areas might have existed during the Cenozoic, favouring terrestrial faunal dispersals between South America and the Greater Antilles along the present-day Lesser Antilles arc. The stratigraphy and depositional environments of the islands of Anguilla, St Martin, Tintamarre, St Barthélemy, Barbuda and Antigua are reviewed in association with multichannel reflection seismic data acquired offshore since the 80's in the Saba, Anguilla and Antigua Banks and in the Kalinago Basin, including the most recent academic and industrial surveys. Seven seismic megasequences and seven regional unconformities are defined, and calibrated from deep wells on the Saba Bank and various dredges performed during marine cruises since the 70's in the vicinity of the islands. Onshore and offshore correlations allow us to depict an updated and detailed sedimentary organisation of the northern part of the Lesser Antilles from the late Eocene to the late Pleistocene. Paleogeographic reconstructions reveal sequences of uplift and emergence across hundredswide areas during the late Eocene, the late Oligocene, the early middle-Miocene and the latest Miocene-earliest Pliocene, interspersed by drowning episodes. The ∼200 km-long and ∼20 km-wide Kalinago Basin opened as an intra-arc basin during the late Eocene - early Oligocene. These periods of emergence may have favoured the existence of episodic mega-islands and transient terrestrial connections between the Greater Antilles, the Lesser Antilles and the northern part of the Aves Ridge (Saba Bank). During the Pleistocene, archipelagos and mega-islands formed repeatedly during glacial maximum episodes.
Published: 2021
Full Text: View/download PDF

21. Acceleration of western Arctic sea ice loss linked to the Pacific North American pattern

Author: Gabriel J. Bowen, Zhongwang Wei, Francis Codron, Zhongfang Liu, Sha Li, Xiaogang He, Camille Risi, Dong Chen, Christopher J. Poulsen, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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)-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), Department of Civil and Environmental Engineering [Singapore], National University of Singapore (NUS), Department of Earth and Environmental Sciences [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, School of Atmospheric Sciences [Zhuhai], Sun Yat-Sen University [Guangzhou] (SYSU), Chinese Academy of Sciences [Beijing] (CAS), Tsinghua University [Beijing] (THU), University of Utah, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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 Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), 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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and 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)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: 0301 basic medicine, 010504 meteorology & atmospheric sciences, Science, [SDV]Life Sciences [q-bio], General Physics and Astronomy, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, 03 medical and health sciences, Downwelling, Sea ice, Arctic climate, Atmospheric science, 0105 earth and related environmental sciences, geography, Multidisciplinary, geography.geographical_feature_category, Greenhouse warming, Advection, General Chemistry, Longwave radiation, Arctic ice pack, 030104 developmental biology, Ocean sciences, Arctic, 13. Climate action, Climatology, Environmental science, human activities, geographic locations
Abstract: Recent rapid Arctic sea-ice reduction has been well documented in observations, reconstructions and model simulations. However, the rate of sea ice loss is highly variable in both time and space. The western Arctic has seen the fastest sea-ice decline, with substantial interannual and decadal variability, but the underlying mechanism remains unclear. Here we demonstrate, through both observations and model simulations, that the Pacific North American (PNA) pattern is an important driver of western Arctic sea-ice variability, accounting for more than 25% of the interannual variance. Our results suggest that the recent persistent positive PNA pattern has led to increased heat and moisture fluxes from local processes and from advection of North Pacific airmasses into the western Arctic. These changes have increased lower-tropospheric temperature, humidity and downwelling longwave radiation in the western Arctic, accelerating sea-ice decline. Our results indicate that the PNA pattern is important for projections of Arctic climate changes, and that greenhouse warming and the resultant persistent positive PNA trend is likely to increase Arctic sea-ice loss., The fastest sea-ice decline has been observed in the western Arctic, but the underlying mechanisms are still unclear. Here, the authors show that the Pacific North American pattern plays an important role in western Arctic sea-ice variability.
Published: 2021
Full Text: View/download PDF

22. Characteristics of hydrate-bound gas retrieved at the Kedr mud volcano (southern Lake Baikal)

Author: Andrey Yu. Manakov, Jeffrey Poort, Alexandr Chenskiy, Hirotsugu Minami, Akihiro Hachikubo, Marc De Batist, Satoshi Yamashita, Gennadiy Kalmychkov, A. V. Khabuev, Oleg Khlystov, Alexey Krylov, Kitami Institute of Technology, Limnological Institute, Siberian Branch of the Russian Academy of Sciences (SB RAS), Saint Petersburg State University (SPBU), A.P. Vinogradov Institute of Geochemistry, Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Renard Centre of Marine Geology (RCMG), Universiteit Gent = Ghent University [Belgium] (UGENT), Irkutsk State University (ISU), and Nikolaev Institute of Inorganic Chemistry [Novosibirsk] (NIC)
Subjects: ANOMALIES, GULF, 010504 meteorology & atmospheric sciences, Hydrogen, Energy science and technology, Clathrate hydrate, chemistry.chemical_element, lcsh:Medicine, 010502 geochemistry & geophysics, 01 natural sciences, Methane, Article, MEXICO, chemistry.chemical_compound, METHANE, Propane, GLOBAL DATASET, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, ISOTOPIC COMPOSITION, lcsh:Science, 0105 earth and related environmental sciences, BASIN, Multidisciplinary, Chemistry, lcsh:R, Sediment, Biogeochemistry, HYDROGEN, Environmental sciences, Neopentane, 13. Climate action, Environmental chemistry, Earth and Environmental Sciences, lcsh:Q, Hydrate, SEDIMENTS, Mud volcano, ETHANE
Abstract: We reported the characteristics of hydrate-bound hydrocarbons in lake-bottom sediments at the Kedr mud volcano in Lake Baikal. Twenty hydrate-bearing sediment cores were retrieved, and methane-stable isotopes of hydrate-bound gases (δ13C and δ2H of − 47.8‰ to − 44.0‰ V-PDB and − 280.5‰ to − 272.8‰ V-SMOW, respectively) indicated their thermogenic origin accompanied with secondary microbial methane. Powder X-ray diffraction patterns of the crystals and molecular composition of the hydrate-bound gases suggested that structure II crystals showed a high concentration of ethane (around 14% of hydrate-bound hydrocarbons), whereas structure I crystals showed a relatively low concentration of ethane (2–5% of hydrate-bound hydrocarbons). These different crystallographic structures comprised complicated layers in the sub-lacustrine sediment, suggesting that the gas hydrates partly dissociate, concentrate ethane and form structure II crystals. We concluded that a high concentration of thermogenic ethane primarily controls the crystallographic structure of gas hydrates and that propane, iso-butane (2-methylpropane) and neopentane (2,2-dimethylpropane) are encaged into crystals in the re-crystallisation process.
Published: 2020
Full Text: View/download PDF

23. Magnetic Fingerprints of Modern Sediments in the South China Sea Resulting From Source‐to‐Sink Processes

Author: Ramon Egli, Pinxian Wang, C. Laj, Michael Sarnthein, Catherine Kissel, Camille Wandres, Climat et Magnétisme (CLIMAG), 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), Institute of Geosciences [Kiel], Christian-Albrechts-Universität zu Kiel (CAU), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), State Key Laboratory of Marine Geology [Shanghai], Tongji University, Central Institute for Meteorology and Geodynamics [Vienna] (ZAMG), 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 École normale supérieure - Paris (ENS-PSL)
Subjects: South china, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Geochemistry, South China Sea, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Geochemistry and Petrology, 14. Life underwater, Source to sink, 0105 earth and related environmental sciences, Magnetite, geography, geography.geographical_feature_category, magnetic mineralogy, Terrigenous sediment, Continental shelf, Sediment, Hematite, Geophysics, chemistry, 13. Climate action, Magnetic mineralogy, visual_art, visual_art.visual_art_medium, marine sediments, Geology
Abstract: More than 650 million tons/year of fluvial sediment are delivered from continental regions into the South China Sea (SCS). Previous studies have shown that the composition of the magnetic fraction of riverine sediments drained into the SCS is significantly variable from north to south. On the basis of this evidence, we now examine a full set of magnetic properties for a number of core‐tops taken at water depth comprised mostly between 800 and 3500 m. Room‐temperature magnetic parameters and thermal spectra are used to obtain information about the concentration and mineralogical magnetic composition. Spatial changes are observed in the relative proportion of magnetite and hematite with an increase of the latter toward the south, similarly to the observation on land. However, the N‐S contrast is much weaker in marine core tops than in river sediments, because of the role played by the shelf in partly trapping river‐borne sediments, in particular in the southern SCS. In part, sediments also reach the continental slope and the deep basins, being transported and mixed by surface and deep‐water currents, which yield the magnetite‐hematite mixing in the south. For the first time, we characterize a wide spectrum of magnetic properties of modern marine sediment in the South China Sea. Our results give important insights into the modern pathways of sediment particles, depicting the source‐to‐sink processes that affect the terrigenous sediment load.
Published: 2018
Full Text: View/download PDF

24. Long-term in situ observations on typhoon-triggered turbidity currents in the deep sea

Author: Zhifei Liu, Shaohua Zhao, Yulong Zhao, Benjamin Charles Kneller, Yanwei Zhang, Xiaodong Zhang, Christophe Colin, Meng Wang, The University of Tennessee [Knoxville], State Key Laboratory of Marine Geology [Shanghai], Tongji University, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), College of Information and Electrical Engineering [Beijing] (CIEE), China Agricultural University (CAU), Delft University of Technology (TU Delft), Division of Animal and Food Microbiology, Center for Clinical Veterinary Medicine, Department of Geology and Petroleum Geology [Aberdeen], and University of Aberdeen
Subjects: Turbidity current, 010504 meteorology & atmospheric sciences, Cruise, Foundation (engineering), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Deep sea, Term (time), Oceanography, 13. Climate action, Typhoon, 14. Life underwater, 0105 earth and related environmental sciences
Abstract: International audience; Turbidity currents regulate the transport of terrigenous sediment, abundant in carbon and nutrients, from the shelf to the deep sea. However, triggers of deep-sea turbidity currents are diverse and remain debatable in individual cases due to few direct measurements and unpredictable occurrence. Here we present long-term monitoring of turbidity currents at a water depth of 2104 m on the margin of the Gaoping Submarine Canyon off Taiwan, which has the world's highest erosion rates and wettest typhoons. The unique 3.5 year record of in situ observations demonstrates the frequent occurrence of deep-sea turbidity currents (an average of six times per year from May 2013 to October 2016), most of which show enhanced sediment flux, raised temperature, and lowered salinity. They are attributed to elevated discharge of the Gaoping River due to typhoons traversing Taiwan. The total duration of these prolonged turbidity currents amounts to 30% of the entire monitoring period, contributing to similar to 72% of total sediment transport in the lower canyon. Our study demonstrates for the first time that typhoons are the most important triggers, in the long term, of frequent turbidity currents and enhanced sediment delivery into the deep sea in the typhoon-river-canyon environment.
Published: 2018
Full Text: View/download PDF

25. Transfer of environmental signals from the surface to the underground at Ascunsă Cave, Romania

Author: V. Drăguşin, S. Balan, D. Blamart, F. L. Forray, C. Marin, I. Mirea, V. Nagavciuc, I. Orăşeanu, A. Perşoiu, L. Tîrlă, A. Tudorache, M. Vlaicu, Institute of Speleology, Romanian Academy, National Institute for Marine Geology and Geoecology, 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: 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, lcsh:Technology, 01 natural sciences, lcsh:TD1-1066, Cave, Environmental monitoring, Organic matter, Precipitation, lcsh:Environmental technology. Sanitary engineering, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, Hydrology, chemistry.chemical_classification, geography, geography.geographical_feature_category, lcsh:T, Stable isotope ratio, Moisture recycling, lcsh:Geography. Anthropology. Recreation, Karst, lcsh:G, chemistry, 13. Climate action, Meteoric water, Geology
Abstract: We present here the results of a 4-year environmental monitoring program at Ascunsă Cave (southwestern Romania) designed to help us understand how climate information is transferred through the karst system and archived by speleothems. The air temperature inside the cave is around 7 °C, with slight differences between the upper and lower parts of the main passage. CO2 concentrations in cave air have a seasonal signal, with summer minima and winter maxima. These might indicate the existence of an organic matter reservoir deep within the epikarst that continues to decompose over the winter, and CO2 concentrations are possibly modulated by seasonal differences in cave ventilation. The maximum values of CO2 show a rise after the summer of 2014, from around 2000 to about 3500 ppm, following a rise in surface temperature. Using two newly designed types of water–air equilibrators, we were able to determine the concentration of CO2 dissolved in drip water by measuring its concentration in the equilibrator headspace and then using Henry's law to calculate its concentration in water. This method opens the possibility of continuous data logging using infrared technology, without the need for costly and less reliable chemical determinations. The local meteoric water line (δ2H = 7.7 δ18O + 10.1), constructed using monthly aggregated rainfall samples, is similar to the global one, revealing the Atlantic as the strongly dominant vapor source. The deuterium excess values, as high as 17 ‰, indicate that precipitation has an important evaporative component, possibly given by moisture recycling over the European continent. The variability of stable isotopes in drip water is similar at all points inside the cave, suggesting that the monitored drip sites are draining a homogenous reservoir. Drip rates, as well as stable isotopes, indicate that the transfer time of water from the surface is on the order of a few days.
Published: 2017
Full Text: View/download PDF

26. Foraminiferal εNd in the deep north-western subtropical Pacific Ocean: Tracing changes in weathering input over the last 30,000 years

Author: Christophe Colin, Franck Bassinot, Eric Douville, Qiong Wu, Giuseppe Siani, Zhifei Liu, Quentin Dubois-Dauphin, François Thil, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), State Key Laboratory of Marine Geology [Shanghai], 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), 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), 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, biology, Holocene climatic optimum, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, 010502 geochemistry & geophysics, biology.organism_classification, Monsoon, 01 natural sciences, Foraminifera, Oceanography, [SDU]Sciences of the Universe [physics], 13. Climate action, Geochemistry and Petrology, Circumpolar deep water, River mouth, 14. Life underwater, Glacial period, ComputingMilieux_MISCELLANEOUS, Holocene, Sea level, 0105 earth and related environmental sciences
Abstract: This study focuses on the neodymium isotopic composition (eNd) of mixed planktonic foraminifera species in sediment cores collected on the north-western margin of the South China Sea (SCS) and in the western equatorial Pacific. The aim was to identify temporal changes in the eNd of the Upper Circumpolar Deep Water (UCDW) during its northward penetration in the western subtropical Pacific and to re-evaluate the significance of deep-water eNd changes at the northern margin of the SCS over the past 25 kyr. The past seawater eNd record derived from sediments of the subtropical western Pacific displays a narrow range from − 2.9 ± 0.3 to − 1.6 ± 0.4. This suggests that the eNd of the UCDW is greatly modified during its northward penetration through the process of boundary exchange along the western volcanic margin of the South Pacific and that the unradiogenic eNd signature of the UCDW observed in the South Pacific (about − 6) has not been propagated beyond the equatorial Pacific, at least not over the last 25 kyr. Seawater eNd values obtained from the northern SCS display large variations with values that are lower (− 6.8 ± 0.3 to − 5.6 ± 0.2) for the last glacial period than for the late Holocene (− 5.7 ± 0.3 to − 4.1 ± 0.2). Such glacial eNd cannot be attributed to a higher proportion of southern-sourced water (SSW) as eNd values of the UCDW in the equatorial western Pacific are more radiogenic than those observed in the SCS. The evolution of the seawater eNd values of the northern SCS during the last glacial period and the last climatic transition is coeval with variations in the contribution of sediments from the Pearl River. The low sea level stand of the last glacial period resulted in a more proximal position of the Pearl River mouth relative to core MD05-2904, which a higher input of freshwater and, in particular, detrital sedimentary particles originating from the Pearl River that partially dissolved during sinking led to a decrease in the seawater eNd along the north-western margin of the SCS. Enhanced rainfalls associated with intensified monsoon and more frequent typhoon activities during the early Holocene Climatic Optimum (from 9 to 7 cal kyr BP) are linked to a decrease in sea surface salinity (lower δ18O values of planktonic foraminifera) and a decrease in eNd values (− 6.2 ± 0.3) induced by lithogenic Nd input from pronounced freshwater and sediment discharge from distal rivers.
Published: 2017
Full Text: View/download PDF

27. Fingerprinting Northeast Atlantic water masses using neodymium isotopes

Author: Qiong Wu, Norbert Frank, Lucile Bonneau, David Van Rooij, Astrid Waldner, Eric Douville, François Thil, Quentin Dubois-Dauphin, Gilles Reverdin, Paolo Montagna, Christophe Colin, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg] = Heidelberg University, Istituto di Science Marine (ISMAR ), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), State Key Laboratory of Marine Geology [Shanghai], Tongji University, RCMG Ghent, Universiteit Gent = Ghent University (UGENT), Interactions et Processus au sein de la couche de Surface Océanique (IPSO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-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), 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), ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), ANR-06-BLAN-0146,NEWTON,NORTH-EST ATLANTIC WATER MASS GEOCHEMICAL TRACERS DURING THE PAST 60 YEARS AND BEYOND(2006), ANR-13-BS06-0003,HAMOC,Dynamique des gyres Nord Atlantique et overturning de la Méditerranée au cours des changements climatiques de l'Holocène(2013), Universität Heidelberg [Heidelberg], Consiglio Nazionale delle Ricerche (CNR), Universiteit Gent = Ghent University [Belgium] (UGENT), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), 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: gyre circulation, Water mass, Antarctic Intermediate Water, Nd isotopic composition, 010504 meteorology & atmospheric sciences, North Atlantic Deep Water, hydrology, Labrador Sea Water, 010502 geochemistry & geophysics, 01 natural sciences, Alboran Sea, Mediterranean sea, Oceanography, [SDU]Sciences of the Universe [physics], 13. Climate action, Geochemistry and Petrology, Circumpolar deep water, Northeast Atlantic, Thermohaline circulation, 14. Life underwater, Surface water, Gulf of Cádiz, Geology, seawater, 0105 earth and related environmental sciences
Abstract: Dissolved neodymium (Nd) isotopic composition (expressed as ?Nd) has been analysed for 82 seawater samples collected from 13 stations stretching from the Alboran Sea to the Iceland Basin. The distribution of the ?Nd values of water masses was thus investigated for the first time along the western European margin in order to explore whether the water masses flowing in the eastern subpolar and subtropical Atlantic reveal distinct isotopic patterns. The Modified Atlantic Water (MAW) in the Alboran Sea displays ?Nd values (between -9.2 ± 0.2 and -8.9 ± 0.2) that are significantly more radiogenic than those reported in previous studies (-10.8 ± 0.2 to -9.7 ± 0.2), suggesting temporal variations in the Nd isotopic composition of the water that enters the Mediterranean Sea from the Strait of Gibraltar. The ?Nd value of the underlying modified Winter Intermediate Water (WIW) has been established for the first time (-9.8 ± 0.3) and is compatible with a Nd signature acquired from the sinking of MAW in the northwestern Mediterranean Sea. Within the Gulf of Cádiz, southern Mediterranean Sea Water (MSW) (-10.6 ± 0.2) differs slightly from the northern MSW (-9.9 ± 0.4) owing to a significant contribution of modified East Antarctic Intermediate Water (EAAIW) (-10.9 ± 0.2). In the northeast Atlantic, the North Atlantic Current surface water located in the inter-gyre region (north of 46°N) displays ?Nd values of between -14.0 ± 0.3 and -15.1 ± 0.3, reflecting the subpolar gyre signature. Along the western European margin, ?Nd values of surface water decrease toward the north (from -10.4 ± 1.6 to -13.7 ± 1.0) in agreement with the gradual mixing between subtropical and subpolar water. At intermediate depth, ?Nd values decrease from -9.9 ± 0.4 within the Gulf of Cádiz to -12.1 ± 0.2 within the Porcupine Seabight, indicating a strong dilution of the MSW with subpolar water. Within the Rockall Trough and the Iceland Basin, the more negative ?Nd values at mid-depth (
Published: 2017
Full Text: View/download PDF

28. Large-scale mass wasting on the Miocene continental margin of western India

Author: Sarah Dailey, Yuting Li, Rakesh Saxena, Tara N. Jonell, Anil Kumar, Manish Tiwari, Giancarlo Scardia, Rajeev Saraswat, Paul B. O'Sullivan, Annette Hahn, Gérôme Calvès, Lisa Tauxe, Sergio Andò, Claire M. Routledge, Boo-Keun Khim, Ravi Mishra, Dhananjai Pandey, Elizabeth M. Griffith, Girish Kumar Sharma, H. Liddy, Nikki E. Neubeck, T. Radhakrishna, James A Bendle, Zhaojie Yu, Jerzy S. Blusztajn, Masao Iwai, Kenta Suzuki, Arun Deo Singh, Denise K. Kulhanek, Mitchell W Lyle, G. P. Gurumurthy, A. Ganesh Kumar, Sophia Aharonovich, Stephan Steinke, Z. Xu, Giovanni Coletti, H. Lu, Peng Zhou, Peter D. Clift, Louisiana State Univ, Texas A&M Univ, Woods Hole Oceanog Inst, UCL, Univ Toulouse 3 Paul Sabatier, GeoSep Serv, Univ Queensland, Natl Ctr Polar & Ocean Res, Univ Milano Bicocca, Purdue Univ, Univ Birmingham, Macquarie Univ, Ohio State Univ, Birbal Sahni Inst Palaeosci, Univ Bremen, Kochi Univ, Pusan Natl Univ, Wadia Inst Himalayan Geol, Natl Inst Ocean Technol, Columbia Univ, Nanjing Univ, Oregon State Univ, Natl Ctr Earth Sci Studies, Natl Inst Oceanog, Oil & Nat Gas Commiss, Universidade Estadual Paulista (Unesp), Kumaun Univ, Banaras Hindu Univ, Xiamen Univ, Hokkaido Univ, Scripps Inst Oceanog, Chinese Acad Sci, Louisiana State University (LSU), 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), School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Banaras Hindu University [Varanasi] (BHU), Dipartimento di Scienze Geologiche e Geotecnologie, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, BITS Pilani, K. K. Birla Campus, Goa (India), Nanjing University (NJU), DEPLAN/IGCE/UNESP, Instituto de Geociencias e Ciencias Exatas, Universidade de São Paulo (USP)-Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), Division of Medical Oncology, University of Colorado [Boulder], Indian Institute of Science, Key Laboratory of Marine Geology and Environment [China, Institute of Oceanology [China], Dailey, S, Clift, P, Kulhanek, D, Blusztajn, J, Routledge, C, Calvès, G, O’Sullivan, P, Jonell, T, Pandey, D, Ando', S, Coletti, G, Zhou, P, Yuting, L, Neubeck, N, Bendle, J, Aharonovich, S, Griffith, E, Gurumurthy, G, Hahn, A, Iwai, M, Khim, B, Kumar, A, Liddy, H, Huayu, L, Lyle, M, Mishra, R, Radhakrishna, T, Saraswat, R, Saxena, R, Scardia, G, Sharma, G, Singh, A, Steinke, S, Suzuki, K, Tauxe, L, Tiwari, M, Zhaokai, X, and Zhaojie, Y
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mass-transport, Arabian Sea, IODP, heavy-minerals, Nataraja Slide, Expedition 355, Mass wasting, 010502 geochemistry & geophysics, 01 natural sciences, Continental margin, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Passive margin, 14. Life underwater, Siltstone, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Continental shelf, Geology, Calcarenite, Geophysics, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Clastic rock, Siliciclastic
Abstract: Made available in DSpace on 2020-12-10T17:04:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Charles T. McCord Jr Chair in Petroleum Geology at Louisiana State University Ministry of Earth Sciences, Government of India National Centre for Polar and Ocean Research (NCPOR) National Research Foundation of Korea CSIR-National Institute of Oceanography, India A giant mass-transport complex was recently discovered in the eastern Arabian Sea, exceeding in volume all but one other known complex on passive margins worldwide. The complex, named the Nataraja Slide, was drilled by International Ocean Discovery Program (IODP) Expedition 355 in two locations where it is similar to 300 m (Site U1456) and similar to 200 m thick (Site U1457). The top of this mass-transport complex is defined by the presence of both reworked microfossil assemblages and deformation structures, such as folding and faulting. The deposit consists of two main phases of mass wasting, each consisting of smaller pulses, with generally fining-upward cycles, all emplaced just prior to 10.8 Ma based on biostratigraphy. The base of the deposit at each site is composed largely of matrix-supported carbonate breccia that is interpreted as the product of debris-flows. In the first phase, these breccias alternate with well-sorted calcar-enites deposited from a high-energy current, coherent limestone blocks that are derived directly from the Indian continental margin, and a few clastic mudstone beds. In the second phase, at the top of the deposit, muddy turbidites dominate and become increasingly more siliciclastic. At Site U1456, where both phases are seen, a 20-m section of hemipelagic mudstone is present, overlain by a similar to 40-m-thick section of calcarenite and slumped interbedded mud and siltstone. Bulk sediment geochemistry, heavy-mineral analysis, clay mineralogy, isotope geochemistry, and detrital zircon U-Pb ages constrain the provenance of the clastic, muddy material to being reworked, Indus-derived sediment, with input from western Indian rivers (e.g., Narmada and Tapti rivers), and some material from the Deccan Traps. The carbonate blocks found within the breccias are shallow-water limestones from the outer western Indian continental shelf, which was oversteepened from enhanced clastic sediment delivery during the mid-Miocene. The final emplacement of the material was likely related to seismicity as there are modern intraplate earthquakes close to the source of the slide. Although we hypothesize that this area is at low risk for future mass wasting events, it should be noted that other oversteepened continental margins around the world could be at risk for mass failure as large as the Nataraja Slide. Louisiana State Univ, Dept Geol & Geophys, E253 Howe Russell Kniffen Geosci Complex, Baton Rouge, LA 70803 USA Texas A&M Univ, Int Ocean Discovery Program, 1000 Discovery Dr, College Stn, TX 77845 USA Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA UCL, Dept Earth Sci, Gower St, London WC1E 6BT, England Univ Toulouse 3 Paul Sabatier, Geosci Environm Toulouse, 14 Ave Edouard Belin, F-31400 Toulouse, France GeoSep Serv, 1521 Pine Cone Rd, Moscow, ID 83843 USA Univ Queensland, Sch Earth & Environm Sci, St Lucia, Qld 4072, Australia Natl Ctr Polar & Ocean Res, Vasco Da Gama 403804, Goa, India Univ Milano Bicocca, Dept Earth & Environm Sci, Piazza Sci 4, I-20126 Milan, Italy Purdue Univ, Dept Earth Atmospher & Planetary Sci, 550 Stadium Mall Dr, W Lafayette, IN 47907 USA Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England Macquarie Univ, Fac Sci & Engn, Dept Earth & Planetary Sci, N Ryde, NSW 2109, Australia Ohio State Univ, Sch Earth Sci, 275 Mendenhall Lab,125 South Oval Mall, Columbus, OH 43210 USA Birbal Sahni Inst Palaeosci, 53 Univ Rd, Lucknow 226007, Uttar Pradesh, India Univ Bremen, MARUM, Leobener Str, D-28359 Bremen, Germany Kochi Univ, Dept Nat Environm Sci, 2-5-1 Akebono Cho, Kochi 7808520, Japan Pusan Natl Univ, Div Earth Environm Syst, Busan 60973, South Korea Wadia Inst Himalayan Geol, 33 GMS Rd, Dehra Dun 248001, Uttrakhand, India Natl Inst Ocean Technol, Marine Biotechnol Dept, Velacheiy Tambaram Main Rd, Chennai 600100, Tamil Nadu, India Columbia Univ, Ctr Climate Syst Res, 2880 Broadway, New York, NY 10025 USA Nanjing Univ, Sch Geog & Oceanog Sci, 163 Xianlin Ave, Nanjing 210023, Jiangsu, Peoples R China Oregon State Univ, Coll Earth Ocean & Atmospher Sci, 104 CEOAS Adm Bldg, Corvallis, OR 97331 USA Natl Ctr Earth Sci Studies, Geosci Div, Aakkulam Trivandrum 695031, India Natl Inst Oceanog, Geol Oceanog Div, Panaji 403004, Goa, India Oil & Nat Gas Commiss, 11 High,Bandra Sion Link Rd, Mumbai 400017, Maharashtra, India Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, 1515 Ave 24-A, BR-13506900 Rio Claro, SP, Brazil Kumaun Univ, Dept Geol, Naini Tal 263002, India Banaras Hindu Univ, Dept Geol, Varanasi 221005, Uttar Pradesh, India Xiamen Univ, Dept Geol Oceanog, Xiamen 361102, Fujian, Peoples R China Xiamen Univ, State Key Lab Marine Environm Sci, Xiamen 361102, Fujian, Peoples R China Hokkaido Univ, Grad Sch Environm Sci, Kita Ku, N10W5, Sapporo, Hokkaido 0600810, Japan Scripps Inst Oceanog, 9500 Gilman Dr, La Jolla, CA 92093 USA Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, 7 Nanhai Rd, Qingdao 266071, Shandong, Peoples R China Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, 1515 Ave 24-A, BR-13506900 Rio Claro, SP, Brazil National Centre for Polar and Ocean Research (NCPOR): 90/2018 National Research Foundation of Korea: 2016R1A2B4008256 National Research Foundation of Korea: 2019R1A2C1007701
Published: 2020
Full Text: View/download PDF

29. Late Quaternary coccolith weight variations in the northern South China Sea and their environmental controls

Author: Chuanlian Liu, Xiang Su, Luc Beaufort, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), 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), 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), and 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)
Subjects: Gephyrocapsa, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, 010504 meteorology & atmospheric sciences, biology, Coccolithophore, Paleontology, Ocean acidification, Plankton, Oceanography, biology.organism_classification, 01 natural sciences, Coccolith, Sea surface temperature, 13. Climate action, 14. Life underwater, Gephyrocapsa oceanica, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Emiliania huxleyi
Abstract: International audience; Coccolithophores are one of the most abundant and widespread groups of calcifying plankton and have attracted extensive study in terms of their likely response to ocean acidification. Conflicting results concerning coccolithophore calcification have been reported from both experimental and field studies. Due to their minute size, it is difficult to estimate the amount of calcite in coccoliths. Here we apply the SYRACO system to analyzing the weights and lengths of coccoliths produced by the dominant coccolithophore family Noelaerhabdaceae. We obtain high-resolution coccolith weight and length records of GEO (Gephyrocapsa oceanica) and SPC (Emiliania huxleyi and small Gephyrocapsa spp.) groups from sediment core MD05-2904 in the northern South China Sea (SCS) over the past 200 kyr. A calcification index (CI) based on the coccolith weight and length is applied to evaluate the changes in coccolithophore calcification. The two groups of coccolith weights / CIs show different patterns on long term variations and during the last two terminations. We compare the coccolith weight and CI records with the environmental variables and carbonate chemistry parameters calculated in the same core. Our data reveals that sea surface temperature and insolation have weak correlations to coccolith weight and CI on long-term variations. The SPC weight / CI are correlated with the seawater pH and pCO(2) variations while the GEO weight/ CI are more related to the nutrient variations. This implies a more significant role of ocean carbonate chemistry in the calcification of less calcified coccolithophores and nutrient concentration in the heavier calcifying coccolithophores.
Published: 2020
Full Text: View/download PDF

30. 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
Full Text: View/download PDF

31. Northern Dobrogea and the Crimean Mountains: The Key Areas in the Tectonic Evolution of the Black Sea Basin

Author: Antoneta Seghedi, Marc Sosson, Mihaela C. Melinte-Dobrinescu, Yevgeniya Sheremet, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), National Institute of Marine Geology and Geoecology (Romania), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, 010504 meteorology & atmospheric sciences, Subduction, Inversion (geology), [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Orogeny, Structural basin, 010502 geochemistry & geophysics, 01 natural sciences, Crimean mountains Northern dobrogea Tectonic evolution Structural analysis Black sea basins, Paleontology, Tectonics, Close relationship, [SDU]Sciences of the Universe [physics], Black sea, Cenozoic, Geology, 0105 earth and related environmental sciences
Abstract: International audience; The work poses the question about the impact of inherited structures in the Black Sea back-arc basin (BAB) tectonic evolution. The new structural analysis of the Northern Dobrogea (ND) and the Crimean Mountains (CM) shows that the origins of structural patterns of both regions are in close relationship with deep faults/or fault zones. The comparative analyses of structures, of tectonic stages and their duration allow us to better understand the connections in time and space between the ND and the CM, against the back-ground of the long-living subduction. In particular during: (1) the Cimmerian orogeny; (2) the opening of the BS and (3) the inversion of the BS during the Cenozoic shortening.
Published: 2019
Full Text: View/download PDF

32. Heat flow in the Western Mediterranean: Thermal anomalies on the margins, the seafloor and the transfer zones

Author: Romain Pellen, Gemma Ercilla, Massimo Bellucci, Alexander Koptevr, Giulia Matilde Ferrante, Virginie Le Gal, Abderrezak Bouzid, Roza Si Bachir, Abdel Karim Yelles-Chaouche, Francis Lucazeau, Anne Battani, Desirée Palomino, Dina R. Gafurova, Marina Rabineau, Jeffrey Poort, Maxime Tremblin, O. Khlystov, Belén Alonso, Sébastien Migeon, Grigory G. Akhmanov, Michela Dal Cin, Estelle Leroux, Angelo Camerlenghi, Sorbonne Université (SU), 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), LabexMER, Gouvernement de la République française, Agencia Estatal de Investigación (España), Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), 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), IFP Energies nouvelles (IFPEN), Istituto Nazionale di Geofisica e di Oceanografia Sperimentale (OGS), 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), Centre de Recherche en Astronomie Astrophysique et Géophysique (CRAAG), 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), Spanish Institute of Oceanography (IEO), Málaga, UNESCO–MSU Centre for Marine Geology and Geophysics, Faculty of Geology, Moscow State University, Vorobjevy Gory, Moscow, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Instituto de Ciencias del Mar de Barcelona (ICM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk, ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-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)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), Sorbonne Universités, Instituto de Ciencias del Mar, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Limnologial Institute of the Siberian Division of the Russina, Chinese Academy of Sciences [Beijing] (CAS), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-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), and Lomonosov Moscow State University (MSU)
Subjects: Mediterranean climate, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Oceanic crust, Liguro-Provençal basin, oceanic crust, Structural basin, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, heat flow, Western Mediterranean Sea, Paleontology, Liguro-Provencal basin, Continental margin, Geochemistry and Petrology, Lithosphere, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Continental margins, Transform fault, Geology, Algero-Balearic basin, Diapir, Seafloor spreading, continental margins, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Heat flow
Abstract: 15 pages, 8 figures, 1 table, supplementary data http://dx.doi.org/10.1016/j.margeo.2019.106064, The Western Mediterranean basin has been formed by Miocene back-arc extension and is underlain by a thin and young lithosphere. This young lithosphere is warm, as testified by an overall elevated offshore heat flow. Heat flow within the Western Mediterranean is, however, highly variable and existing data are unevenly distributed and poorly studied in the central part of the Liguro-Provençal and Algero-Balearic basins. This central part is floored by a young oceanic crust, bordered by different continental margins, cut by transform faults, and filled by up to 8 km of sediments. We present a total of 148 new heat flow data collected during the MedSalt and WestMedFlux cruises in 2015 and 2016 and aligned along seven regional profiles that show an important heat flow variability on the basin-scale, but also locally on the margins. A new heat flow map for the Western Mediterranean outlines the following regional features: (1) a higher average heat flow in the Algero-Balearic basin compared to the Liguro-Provençal basin (94 ± 13 mW/m2 and 78 ± 16 mW/m2, respectively), and (2) a regional thermal asymmetry in both basins, but with opposed heat flow trends. Up to 20% of this heat flow difference can be explained by sediment blanketing, but age and heterogeneity of ocean crust due to an asymmetric and polyphased opening of the basins are believed to have given the major thermal imprint. Estimates of the age of the oceanic crust based on the new heat flow suggest a considerably younger West Algerian basin (16–23 Ma) compared to the East Algerian basin and the West Sardinia oceanic floor (31–37 Ma). On the margins and ocean-continent transitions of the Western Mediterranean the new heat flow data point out the existence of two types of local anomalies (length scale 5–30 km): (1) locally increased heat flow up to 153 mW/m2 on the Gulf of Lion margin results from thermal refraction of large salt diapirs, and (2) the co-existing of both low (110 mW/m2) heat flow areas on the South Balearic margin suggests a heat redistribution system. We suspect the lateral heat advection is resulting from a regional fluid circulation in the sediments associated to the widespread Plio-Pleistocene volcanism on the South Balearic margin, This work was also supported by the “Laboratoire d'Excellence” LabexMER (ANR-10-LABX-19) and co-funded by a grant from the French government under the program “Investissements d'Avenir”, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)
Published: 2019
Full Text: View/download PDF

33. Magnetic signature of river sediments drained into the southern and eastern part of the South China Sea (Malay Peninsula, Sumatra, Borneo, Luzon and Taiwan)

Author: Camille Wandres, Catherine Kissel, Jinhua Li, Zhifei Liu, 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), State Key Laboratory of Marine Geology [Shanghai], Tongji University, CAS Key Laboratory of Earth and Planetary Physics (EPP), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), 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, Water mass, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Stratigraphy, Drainage basin, Geology, Structural basin, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Oceanography, 13. Climate action, Magnetic mineralogy, engineering, 14. Life underwater, Precipitation, Parent rock, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Clay minerals, Pyrrhotite, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Magnetic properties of 22 river samples collected in the Malay Peninsula, Sumatra, Borneo, Luzon and Taiwan have been investigated in order to magnetically characterize the sediments drained and deposited into the South China Sea. The geological formations as well as the present climatic conditions are different from one region to another. Laboratory analyses include low-field magnetic susceptibility, anhysteretic (ARM) and isothermal (IRM) remanent magnetizations acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis cycles and low-temperature magnetic measurements. The magnetic properties indicate that the sediments are a mixture of hematite, magnetite and pyrrhotite in different proportions depending on the region. Combined with results previously reported for the three main Asian rivers (Pearl, Red and Mekong rivers), the new data indicate that, in general, hematite-rich sediments are delivered to the southern basin of the South China Sea while the northern basin is fed with magnetite and pyrrhotite-rich sediments. In addition to this general picture, some variability is observed at smaller geographic scales. Indeed, the magnetic assemblages are closely related to the geology of the various catchments while clay minerals, previously reported for the same samples, are more representative of the climatic conditions under which the parent rocks have evolved within each catchment. The magnetic fraction, now well characterized in the main river sediments drained into the South China Sea, can be used as a tracer for changes in precipitation on land and in oceanic water mass transport and exchange.
Published: 2017
Full Text: View/download PDF

34. Climatic control of sediment transport from the Himalayas to the proximal NE Bengal Fan during the last glacial-interglacial cycle

Author: Virginia Rojas, Franck Bassinot, Zhifei Liu, Laure Meynadier, Christophe Colin, Kelly Fauquembergue, Frédéric Schmidt, Ronan Joussain, Sébastien Zaragosi, Léa Fournier, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), State Key Laboratory of Marine Geology [Shanghai], Tongji University, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-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-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), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), 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 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), 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), Service de Radiologie [CHU Caen], Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN), Sécurité et Durabilité des Ouvrages d'Art (IFSTTAR/MAST/SDOA), and Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Communauté Université Paris-Est
Subjects: Archeology, 010504 meteorology & atmospheric sciences, Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Panoply, chemistry.chemical_compound, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Chlorite, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Geology, 15. Life on land, Turbidite, Oceanography, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, Illite, Interglacial, engineering, Erosion, Siliciclastic, Sedimentary rock
Abstract: International audience; Clay mineralogy, siliciclastic grain-size, major elements, 87Sr/86Sr, and εNd analyses of deep-sea sediments cored in the north-eastern Bay of Bengal are used to reconstruct evolution of detrital sources and sediment transport to the proximal part of the Bengal deep-sea fan during the last climatic cycle. εNd values (−13.3 to −9.7) and 87Sr/86Sr ratios (0.721–0.733) indicate a mixture of sediments originating from the Ganges-Brahmaputra rivers and the Indo-Burman ranges. Interglacial Marine Isotopic Stages (MIS) 5 and 1 are associated with a higher contribution of sediments from the Ganges-Brahmaputra river system than is the case for glacial MIS 6, 4, 3, and 2. Siliciclasitic grain-size combined with Si/Al and Si/Fe ratios indicate coarser glacial sediments with numerous turbidite layers. Glacial turbidite layers display similar clay mineralogical compositions to hemipelagic sediments. Only few of turbidite layers (MIS 6, 4, and 2) are slightly unradiogenic (εNd −13.3), suggesting a higher contribution of Ganges-Brahmaputra river sediments. Independently of changes in the sedimentary sources, the smectite/(illite + chlorite) ratio of cores located on the NE Bengal Fan indicates higher inputs of primary minerals (illite and chlorite) from the highlands of the river basins (relief) during glacial MIS 6, 4, 3, and 2 and an increased contribution of pedogenic minerals (smectite and kaolinite) during interglacial MIS 5 and 1. Maximum smectite/(illite + chlorite) ratios during the warm sub-stages of MIS 5 suggest an intensification of summer monsoon rainfall associated with higher rates of physical erosion of the Indo-Gangetic flood-plain and/or dominant summer hydrological conditions transporting a higher proportion of sediments deriving from the Ganges-Brahmaputra rivers to the NE Bengal Fan. In addition, a higher production of smectite in soils of the Indo-Gangetic flood-plain during periods of intensification of monsoon rainfall cannot be excluded.
Published: 2016
Full Text: View/download PDF

35. Source-to-sink transport processes of fluvial sediments in the South China Sea

Author: Chih-An Huh, Shouting Tuo, Yanwei Zhang, Edlic Sathiamurthy, Christophe Colin, Wahyoe S. Hantoro, Chi Yue Huang, Karl Stattegger, Jianguo Liu, Chen-Feng You, Xiajing Li, Khanh Phon Le, Ziding He, Suratta Bunsomboonsakul, Yuchen Wang, James T. Liu, Yanli Li, Martin G. Wiesner, Zhifei Liu, Shaohua Zhao, Fernando P. Siringan, Yulong Zhao, Shiwen Zhou, Penjai Sompongchaiyakul, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institute of Geosciences, University of Kiel, Kiel University, Institute of Geology, University of Hamburg, Hamburg 20146, Germany, University of Hamburg, Institute of Earth Sciences [Tapei] (IES Sinica), Academia Sinica, Department of Marine Science, Chulalongkorn University, Bangkok 10330, Thailand, Chulalongkorn University [Bangkok], Department of Earth Sciences, National Cheng Kung University, Tainan 70101, Taiwan, National Cheng Kung University (NCKU), Department of Oceanography, National Sun Yat-sen University, Kaohsiung 80424, Taiwan, National Sun Yat-Sen University (NSYSU), Marine Science Institute [Philippines Univ], University of the Philippines Diliman (UP Diliman), Faculty of Petroleum, Hanoi University of Mining and Geology, Hanoi, Vietnam, Hanoi University of Mining and Geology (HUMG), Malaysia Institute of Oceanography, University of Malaysia, Research Center for Geotechnology, and Indonesian Institute of Sciences (LIPI)
Subjects: geography, Provenance, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Terrigenous sediment, Continental shelf, Sediment, engineering.material, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Oceanography, [SDU]Sciences of the Universe [physics], 13. Climate action, Illite, engineering, General Earth and Planetary Sciences, 14. Life underwater, Glacial period, Sediment transport, Geology, 0105 earth and related environmental sciences
Abstract: The South China Sea offers an excellent case for studying source-to-sink transport processes of fluvial sediments among the global marginal seas. This study synthesizes existing clay mineralogical and geochemical data from similar to 1500 samples from the seafloor and surrounding rivers, deepwater mooring observation results, and high resolution glacial-cyclic clay mineralogy records from six high-quality sediment cores. Source-to-sink sediment transport from the river mouth to the continental shelf and then to the abyssal basin is investigated at two time scales: modern process and Late Quaternary glacial cycles. The results firstly show the high diversity of clay mineralogical and geochemical compositions in riverbed surface sediments surrounding the South China Sea, e.g., dominant illite and chlorite in Taiwan, overwhelming majority of smectite in Luzon, dominant kaolinite in South China, and similar amounts of the four clay mineral species in Red and Mekong river systems. The formation of these fluvial sediments through chemical weathering in surrounding drainage systems is controlled principally by the East Asian monsoon climate with warm temperature and high precipitation, and subordinately by tectonic activity and specific lithological character. The basin-wide distribution of clay mineral assemblages combined with neodymium and strontium isotopic compositions reflects strong provenance control and differential settling effects. The differential settling of kaolinite in slightly saline and proximal regions relative to smectite in more saline and distal regions is well demonstrated in the South China Sea. Through combining clay mineralogical distributions on the seafloor with observed oceanic current systems, the modern transport pathways can be well established, e.g., in the northern South China Sea, illite and chlorite from Taiwan are mainly carried by contour currents with the strong influence of mesoscale eddies. High-resolution sediment dynamic analysis for the Late Quaternary reveals different sediment transport patterns in the northern, western, and southern South China Sea when the land-sea configuration dramatically changed during glacial conditions. In the north, the terrigenous dispersal is mainly controlled by provenance supply and oceanic current transport. In the west, the clay mineral assemblage reflects variations of the prevailing surface current influenced by monsoon winds. In the south, the clay mineral input indicates intensive chemical weathering during interglacial periods and strengthened physical erosion during glacial periods. The transport of terrigenous sediments since the last glaciation is quantitatively reconstructed through studying two deepwater sediment cores located in the northern South China Sea. The relative contributions from three provenances (South China, Luzon, and Taiwan) highlight their distinct variability over the last 28 ka, implying that the southward shift of the inter-tropical convergence zone (ITCZ) at 16 Ka BP caused an increased sediment contribution from South China, the intensified influence of the Kuroshio Current intrusion controls more efficient westward transport of Luzon sediments, and the stronger deepwater current transports Taiwan-sourced sediments further westward from the last glaciation to the Holocene. (C) 2015 Elsevier B.V. All rights reserved.
Published: 2016
Full Text: View/download PDF

36. The Zambezi delta (Mozambique channel, East Africa): High resolution dating combining bio-orbital and seismic stratigraphy to determine climate (palaeoprecipitation) and tectonic controls on a passive margin

Author: Jean-Pierre Ponte, Gérard Dupont, Speranta Maria Popescu, Jéremie Gaillot, Mihaela Carmen Melinte-Dobrinescu, Miroslav Bubík, François Guillocheau, Jean-Pierre Suc, Cécile Robin, Massimo Dall’asta, Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), GeoBioStratData.Consulting, 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), TOTAL S.A., TOTAL FINA ELF, National Institute of Marine Geology and Geoecology (Romania), Czech Geological Survey [Praha], Total, Institut Français de Recherche pour l'Exploitation de la Mer, Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-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 de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Delta, 010504 meteorology & atmospheric sciences, Stratigraphy, Biostratigraphy, 010502 geochemistry & geophysics, Oceanography, Neogene, Palaeoclimate, 01 natural sciences, Paleontology, Passive margin, East African Rift, Sequence stratigraphy, Mozambique, 0105 earth and related environmental sciences, geography, Plateau, geography.geographical_feature_category, Geology, 15. Life on land, Geophysics, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Zambezi, Economic Geology, Orbital stratigraphy, Cenozoic, Seismic stratigraphy
Abstract: International audience; The Zambezi Delta draining the Southern African Plateau and the southern part of the East African Rift is one of a the largest delta of Africa with a long-lasting history starting during Early Cretaceous with more than 12 km of sediments deposited. The Zambezi Delta is therefore a unique archive of the past topographic evolution of southern and eastern Africa and their related deformations, but also of the climate changes, global and regional (consequences of local topographic growths). Understanding this archive supposes to get a high-resolution dating of the sediments. Our two objectives are here (1) to construct an age model of the Zambezi Cenozoic delta using a combination of biostratigraphy, orbital stratigraphy and sequence stratigraphy and (2) to determine the palaeoprecipitation variations of the Zambezi catchment from the Oligocene to present day in a known tectonic framework. The Neogene sequences were dated at high-resolution assuming that the third order sequences are of eustatic origin and record long-term eccentricity cycles. The sequences were correlated in ages on the calculated Earth orbital solutions of Laskar for the time intervals provided by the biostratigraphy (nannofossils, planktonic foraminifers). The palaeoprecipitation record was based on the definition of a humidity index based on pollen analysis and associated botanical associations. The late Oligocene was a quite wet period getting dryer in the uppermost Chattian. The base Tortonian (11 Ma) was a humid period. The Messinian was a dry period with a slight increase of the humidity during the Zanclean and a sharp increase around the Zanclean-Piacenzian boundary. The Zambezi Delta has recorded the uplifts of the Southern African Plateau (around 85 Ma and around 25 Ma) and those of the southward migration of the East African Rift (since 5.5 Ma).
Published: 2019
Full Text: View/download PDF

37. Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Author: Yannick Thomas, Carla Scalabrin, Bruno Marsset, C. Bernard, Vincent Riboulot, G. Ion, Nabil Sultan, Stephan Ker, Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne), Département STIC [Brest] (STIC), and National Institute for Marine Geology and Geo-ecology (GeoEcoMar )
Subjects: Transient state, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Clathrate hydrate, Geochemistry, excess pore pressure, gas hydrate, 010502 geochemistry & geophysics, 01 natural sciences, Excess pore pressure, Geophysics, Black Sea, 13. Climate action, Geochemistry and Petrology, Gas hydrate, Black sea, 14. Life underwater, BSR, Geology, 0105 earth and related environmental sciences
Abstract: International audience; A comprehensive characterization of the gas hydrate system offshore the western Black Sea was performed through an integrated analysis of geophysical data. We detected the Bottom Simulating Reflector (BSR), which marks, in this area, the base of gas hydrate stability. The observed BSR depth does not fit the theoretical steady-state base of gas hydrate stability zone (BGHSZ). We show that the disparity between the BSR and predicted BGHSZ is the result of a transient state of the hydrate system due to the ongoing re-equilibrium since the Last Glacial Maximum. When gas hydrates are brought outside the stability zone due to changes in temperature and sea level, their dissociation generates an increase in interstitial pore pressure. This process is favorable to the re-crystallization of gas hydrates and delays the upward migration of the hydrate stability zone explaining the anomalously deep BSR. The BSR depth, which is commonly used to derive geothermal gradient values by assuming steady state conditions, is used here to derive the maximum excess pore pressure at the base of the gas hydrate stability zone. Derived excess pore pressure values of 1-2 MPa are probably the result of the low permeability of hydrate-bearing sediments. Higher pore pressure values derived at the location of a fault system could cause hydro-fracturing enabling the free gas to cross the gas hydrate stability zone and emerge at the seafloor, forming the flares observed in close vicinity to where the shallow gas hydrates were sampled.
Published: 2019
Full Text: View/download PDF

38. Rapid transition from continental breakup to igneous oceanic crust in the South China Sea

Author: Xiao-Long Huang, R. Xiang, Weiping Ding, A.J. Gewecke, Benjamin G. Johnson, Liyan Tian, Sara Satolli, Michael Nirrengarten, Z. Sun, R. Yadav, Hong Jin, Lachit S. Ningthoujam, Kan-Hsi Hsiung, H.C. Larsen, Michael J. Dorais, Eric C. Ferré, Ning Zhao, Z. Jian, David W. Peate, A. Luna, Shijun Jiang, Liang Yi, Yang Zhang, L. Li, C.M. Robinson, Robert Kurzawski, Jessica L. Hinojosa, Deniz Cukur, Stephen A. Bowden, Julie Schindlbeck, P. S. Yu, N. Osono, T. W. Höfig, Adam Klaus, Chih-Chieh Su, L. Zhong, C. Lupi, Jacopo Boaga, S.M. Skinner, Kelsie Dadd, A. Furusawa, Jian Lin, Zhifei Liu, Carlos A. Alvarez-Zarikian, H. Wu, Patricia Persaud, Yifeng Chen, Enqing Huang, Chunji Liu, Y. Li, G. Zhong, N. Qiu, Susanne M. Straub, J. Zhang, Shiming Wan, Chao Lei, Fabricio Ferreira, B. Li, C. Zhang, Isabel Sauermilch, Joann M. Stock, Geoffroy Mohn, Anne Briais, X. Su, Anders McCarthy, Baoqi Huang, F.M. van der Zwan, Dynamique de la lithosphère et des bassins sédimentaires (IPGS) (IPGS-Dylbas), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences et Environnement Cergy (GEC), Fédération INSTITUT DES MATÉRIAUX DE CERGY-PONTOISE (I-MAT), Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine, Department of Mathematics and Statistics, University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System, Nanjing Electronic Devices Institute, C Electronic Devices Institute, Texas A&M University [College Station], Dynamique terrestre et planétaire (DTP), 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), 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)-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), inconnu, Inconnu, Institut Méditerranéen d'Ecologie et de Paléoécologie (IMEP), Université Paul Cézanne - Aix-Marseille 3-Université de Provence - Aix-Marseille 1-Avignon Université (AU)-Centre National de la Recherche Scientifique (CNRS), Universidad de Talca, Department of Electrical Engineering, University of Nebraska–Lincoln, University of Nebraska System-University of Nebraska System, Montpellier Research in Management (MRM), Université Paul-Valéry - Montpellier 3 (UPVM)-Université de Perpignan Via Domitia (UPVD)-Groupe Sup de Co Montpellier (GSCM) - Montpellier Business School-Université de Montpellier (UM), School of Geographic and Oceanographic Sciences, Nanjing University (NJU), Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences [Beijing] (CAS), Laboratoire du Futur (LOF), Université Sciences et Technologies - Bordeaux 1 (UB)-RHODIA-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche en Energie Electrique de Nantes Atlantique EA4642 (IREENA), Institut Universitaire de Technologie Saint-Nazaire (IUT Saint-Nazaire), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Institut Universitaire de Technologie - La Roche-sur-Yon (IUT La Roche-sur-Yon), Université de Nantes (UN)-Université de Nantes (UN), Imperial College London, Key Laboratory of Marine Geology and Environment [China, Institute of Oceanology [China], Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin [Austin], Hunan Research Academy of Environmental Sciences, Paul Scherrer Institute (PSI), Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), AIR (AIR), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Centre National de la Recherche Scientifique (CNRS), Université Paul Cézanne - Aix-Marseille 3-Centre National de la Recherche Scientifique (CNRS)-Avignon Université (AU)-Université de Provence - Aix-Marseille 1, University of Nebraska [Lincoln], Université Montpellier 1 (UM1)-Groupe Sup de Co Montpellier (GSCM) - Montpellier Business School-Université Paul-Valéry - Montpellier 3 (UPVM)-Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Perpignan Via Domitia (UPVD), Université Sciences et Technologies - Bordeaux 1-RHODIA-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche en Electrotechnique et Electronique de Nantes Atlantique EA4642 (IREENA), and Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Rift, 010504 meteorology & atmospheric sciences, International Ocean Discovery Program, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Paleontology, Igneous rock, 13. Climate action, Oceanic crust, Passive margin, Lithosphere, Magmatism, General Earth and Planetary Sciences, 14. Life underwater, Earth and Planetary Sciences (all), Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Continental breakup represents the successful process of rifting and thinning of the continental lithosphere, leading to plate rupture and initiation of oceanic crust formation. Magmatism during breakup seems to follow a path of either excessive, transient magmatism (magma-rich margins) or of igneous starvation (magma-poor margins). The latter type is characterized by extreme continental lithospheric extension and mantle exhumation prior to igneous oceanic crust formation. Discovery of magma-poor margins has raised fundamental questions about the onset of ocean-floor type magmatism, and has guided interpretation of seismic data across many rifted margins, including the highly extended northern South China Sea margin. Here we report International Ocean Discovery Program drilling data from the northern South China Sea margin, testing the magma-poor margin model outside the North Atlantic. Contrary to expectations, results show initiation of Mid-Ocean Ridge basalt type magmatism during breakup, with a narrow and rapid transition into igneous oceanic crust. Coring and seismic data suggest that fast lithospheric extension without mantle exhumation generated a margin structure between the two endmembers. Asthenospheric upwelling yielding Mid-Ocean Ridge basalt-type magmatism from normal-temperature mantle during final breakup is interpreted to reflect rapid rifting within thin pre-rift lithosphere.
Published: 2018
Full Text: View/download PDF

39. Technical note: A refinement of coccolith separation methods: measuring the sinking characteristics of coccoliths

Author: Xiao-Bo Jin, Heather Stoll, Hongrui Zhang, Clara T Bolton, Chuanlian Liu, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), 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), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), 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), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-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)
Subjects: Laboratory methods, 010504 meteorology & atmospheric sciences, [SDE.IE]Environmental Sciences/Environmental Engineering, lcsh:QE1-996.5, lcsh:Life, Mineralogy, Technical note, 010502 geochemistry & geophysics, 01 natural sciences, Method development, Coccolith, lcsh:Geology, lcsh:QH501-531, Settling, lcsh:QH540-549.5, Separation method, lcsh:Ecology, Ecology, Evolution, Behavior and Systematics, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Quantification sinking velocities of individual coccoliths will contribute to optimizing laboratory methods for separating coccoliths of different sizes and species for geochemical analysis. The repeated settling–decanting method was the earliest method proposed to separate coccoliths from sediments and is still widely used. However, in the absence of estimates of settling velocity for nonspherical coccoliths, previous implementations have depended mainly on time-consuming empirical method development by trial and error. In this study, the sinking velocities of coccoliths belonging to different species were carefully measured in a series of settling experiments for the first time. Settling velocities of modern coccoliths range from 0.154 to 10.67 cm h−1. We found that a quadratic relationship between coccolith length and sinking velocity fits well, and coccolith sinking velocity can be estimated by measuring the coccolith length and using the length–velocity factor, kv. We found a negligible difference in sinking velocities measured in different vessels. However, an appropriate choice of vessel must be made to avoid “hindered settling” in coccolith separations. The experimental data and theoretical calculations presented here support and improve the repeated settling–decanting method.
Published: 2018
Full Text: View/download PDF

40. Responses of the East Asian Summer Monsoon in the Low-Latitude South China Sea to High-Latitude Millennial-Scale Climatic Changes During the Last Glaciation: Evidence From a High-Resolution Clay Mineralogical Record

Author: Zhifei Liu, Christophe Colin, Shaohua Zhao, Yulong Zhao, Xingxing Wang, Zhimin Jian, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), and Qingdao Agricultural University
Subjects: clay mineralogy, Atmospheric Science, Low latitude, South china, 010504 meteorology & atmospheric sciences, Paleontology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, South China Sea, 010502 geochemistry & geophysics, Oceanography, East Asian summer monsoon, 01 natural sciences, last glaciation, millennial-scale climatic change, 13. Climate action, [SDU]Sciences of the Universe [physics], High latitude, East asian summer monsoon, 14. Life underwater, Physical geography, Glacial period, Scale (map), Geology, 0105 earth and related environmental sciences
Abstract: International audience; High‐resolution clay mineral assemblage combined with Nd and Sr isotopic compositions of Core MD12‐3434 located in the northern South China Sea was investigated to reveal terrigenous sediment response to the East Asian monsoon evolution during the last glaciation. Clay mineralogical variations indicate clear millennial‐scale oscillations that are mainly due to rapid changes in the proportion of smectite to illite and chlorite. Smectite is derived predominantly from rapid chemical weathering of volcanic rocks in Luzon under strong summer monsoon, while illite and chlorite are mainly sourced from Taiwan through reinforced physical erosion. Thus, the smectite/(illite + chlorite) ratio is adopted to reconstruct the East Asian summer monsoon evolution during the last glaciation. Rapid increases in the smectite/(illite + chlorite) ratio imply strengthened summer monsoon occurred during Dansgaard‐Oeschger and Bølling‐Allerød interstadials. In contrast, rapid decreases in the ratio indicate relatively weakened summer monsoon happened during Heinrich and Younger Dryas stadials. These millennial‐scale climatic signals documented by clay mineralogical compositions of deep‐sea sediments in the South China Sea can be better preserved in calm deeper‐water sedimentary environments. Our study highlights the prompt responses of the East Asian monsoon system to millennial‐scale climatic changes occurred in high‐latitude Northern Hemisphere through contemporaneous chemical weathering of volcanic rocks and/or sediment supply variations under strong physical erosion in the low‐latitude South China Sea, implying an atmospheric teleconnection from the North Atlantic to the Asian monsoon region.
Published: 2018
Full Text: View/download PDF

41. Seasonal variations in dissolved neodymium isotope composition in the Bay of Bengal

Author: Qiong Wu, Christophe Colin, Gilles Reverdin, Zhaojie Yu, Arnaud Dapoigny, Eric Douville, Shiming Wan, F. Bassinot, Zhaokai Xu, Laure Meynadier, Lina Song, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), 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), 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), Interactions et Processus au sein de la couche de Surface Océanique (IPSO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), State Key Laboratory of Marine Geology [Shanghai], Tongji University, Institute of Oceanology [China], Paléocéanographie (PALEOCEAN), ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), ANR-11-BS56-0024,MONOPOL,Paléo-variabilité de la mousson indienne(2011), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-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), 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 Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636))
Subjects: Monsoon of South Asia, Radiogenic nuclide, 010504 meteorology & atmospheric sciences, Weathering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Particulates, 010502 geochemistry & geophysics, 01 natural sciences, 6. Clean water, Panoply, Geophysics, Oceanography, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, TRACER, Earth and Planetary Sciences (miscellaneous), Seawater, 14. Life underwater, Transect, Bay, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Constraining the dissolved neodymium (Nd) cycle in the ocean is paramount for using Nd isotopic composition ( e Nd ) as a tracer to reconstruct deep-sea paleocirculations or continental weathering on different time scales. Dissolved eNd has been measured in seawater samples from six hydrological stations collected along ∼89°E North–South transect in the Bay of Bengal (BoB) in order to assess the impact of seasonal freshwater and sediment discharges from the continental river systems. Seawater samples collected in this study during June 2012 reveal more radiogenic eNd (a difference of ∼2 Epsilon units for the upper 2000 m, and ∼0.5 Epsilon unit below 2000 m) and ∼3–8 pmol/kg lower Nd concentrations than the reported values of nearby seawater samples collected in November 2008. These observations are most plausibly explained by a seasonal variations in dissolved Nd concentrations and eNd in the BoB, induced by seasonal variations in the freshwater and sediment discharges from the Ganges–Brahmaputra (G–B) river system. However, we cannot entirely exclude the possibility of spatial differences given that the water stations collected in this study are not exactly the same positions collected in November 2008. A two-box model suggests, (1) the particulate Nd inputs from the G–B river system mainly control the seasonal shift of eNd observed in the BoB seawater, and (2) a very rapid Nd exchange exists between lithogenic particles and seawater (at least on the scale of a few months). Seasonal changes in seawater eNd may also occur in other marginal seas and in the outflows of major rivers, and these need to be taken into account when using the eNd proxy in the ocean.
Published: 2017
Full Text: View/download PDF

42. Holocene Sediment Mobilization in the Inner Continental Shelf of the Bay of Biscay: Implications for Regional Sediment Budget Offshore to Onshore

Author: Magaly Koch, Erwan Gensac, Romain Le Gall, Muthuvairavasamy Ramkumar, Jean-Baptiste Cherfils, David Menier, Guilhem Estournès, Mouncef Sedrati, Franto Novico, Manoj Joseph Mathew, François Guillocheau, Evelyne Goubert, Laboratoire Géosciences Océan (LGO), 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), Universiti Teknologi PETRONAS (UTP), Periyar University, Institut de Géoarchitecture, Institut Brestois des Sciences de l'Homme et de la Société (IBSHS), Université de Brest (UBO)-Université de Brest (UBO)-Université de Brest (UBO)-Université de Bretagne Sud (UBS), Boston University [Boston] (BU), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Marine Geology Research and Development of Ministry of Energy and Mineral Resources, Université de Bretagne Sud (UBS)-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 de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-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 Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Brestois des Sciences de l'Homme et de la Société (IBSHS), Université de Brest (UBO)-Université de Brest (UBO), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-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 de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, coastline variations, Hallermeier, 01 natural sciences, sediment transport, spatio-temporal scale, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 14. Life underwater, Sedimentary budget, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, 010505 oceanography, Continental shelf, Sediment, geomorphological behavior, Depth of closure, Oceanography, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Submarine pipeline, Sediment transport, Bay, Geology
Abstract: International audience; Sediment mobilization, especially from offshore bay to the coast during the Holocene, along the inner continental shelf of Bay of Biscay is less understood. Acoustic and sediment sampling and surveys were conducted offshore of the Bay of Étel to define the shallow geologic framework and the sedimentology. Results of these campaigns are used to identify and map Holocene deposits, discuss sediment transport pathways and depth of closure using Hallermeier's approach in order to define the active sedimentary prism using the depth of closure on a meso-tidal and wave dominated coast. In the Bay of Étel, Holocene sediments are concentrated between rocky shoals and emerged rocks, passing from external zone by sand lobe, 20 m thick to the medium zone, 15 m thick, to the beaches of the Gâvres-Penthièvre beach dune system (modern coastal prism). This case study found that the thickest deposits of Quaternary sediments observed along the inner shelf have a strong dependence on coastal topography and structural heritage. The presence of offshore basement shoal has been determined to have exercised control over sediment transfers from offshore to landward regions during the last marine inundation. Due to the lack of any significant modern fluvial input of sand in the region, the Holocene deposits are inferred to have been derived by reworking of relict Pleistocene and older inner-shelf deposits. Sediment textural trends and seafloor morphology from the medium zone to the beach dune system indicate an absence of relationships (linking) between the modern sedimentary prism and the potential source of sediment to the shoreline.
Published: 2019
Full Text: View/download PDF

43. A two-step expansion of the dinocyst Lingulodinium machaerophorum in the Caspian Sea: the role of changing environment

Author: Hamid Lahijani, P. Habibi, Alina Tudryn, Suzanne A.G. Leroy, M. Shah-Hosseini, Klaus Arpe, A. Makhlough, Jean-Louis Reyss, S. Shahkarami, Françoise Chalié, S. Haghani, H. S. Nasrollahzadeh, Institute for the Environment [Uxbridge], Brunel University London [Uxbridge], INIO, Iranian National Institute for Oceanography, 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), Océan et Interfaces (OCEANIS), 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), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Tehran School of Geology, University of Tehran, Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Meteorologie (MPI-M), Max-Planck-Gesellschaft, Caspian Sea Ecology Research Center Iran (CSERC), Ecology Departments, Marine Geology Department, Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), 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), School of Geology (Iran), Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), European Project: 247512,EC:FP7:PEOPLE,FP7-PEOPLE-2009-IRSES,CLIMSEAS(2010), 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)-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), 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]Sciences of the Universe [physics]/Earth Sciences, Structural basin, 01 natural sciences, Dinocysts, Past sea surface temperature, Dinocyst, Last millennia, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Sea level, Holocene, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Global warming, Sediment, Geology, Sedimentation, Last centuries, Sea surface temperature, Oceanography, 13. Climate action, Caspian Sea
Abstract: International audience; Dinoflagellate cyst assemblages were analysed in four short sediment cores collected in the south Basin of the Caspian Sea for assessing environmental changes over the last few millennia. Two of these cores were dated by radionuclides. The sedimentation rate of one of them was very high, in the order of 20 mm per year. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the concentration of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, it became clear that this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last decades, we show that the main forcing for the recent increase of L. machaerophorum percentages and concentration is global climate change, especially sea surface temperature increase. Sea level fluctuations likely only have a minor impact. We argue that the recent increase in L. machaerophorum indicates that the Caspian Sea clearly is in the Anthropocene.
Published: 2013
Full Text: View/download PDF

44. The sensitivity of gas hydrate reservoirs to climate change: Perspectives from a new combined model for permafrost-related and marine settings

Author: Marc De Batist, Thomas Mestdagh, Jeffrey Poort, Renard Centre of Marine Geology, Gent University, Evolution et Modélisation des Bassins Sédimentaires (EMBS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and Universiteit Gent = Ghent University (UGENT)
Subjects: 010504 meteorology & atmospheric sciences, Earth science, Clathrate hydrate, Climate change, Permafrost, 010502 geochemistry & geophysics, 01 natural sciences, Methane, Modelling, chemistry.chemical_compound, Deglaciation, Gas hydrate, 14. Life underwater, Geomorphology, 0105 earth and related environmental sciences, Marine, Global warming, 15. Life on land, chemistry, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Greenhouse gas, General Earth and Planetary Sciences, Hydrate, Geology
Abstract: International audience; Gas hydrate reservoirs store large quantities of gas in sediments on continental margins, in deep lakes, and in continental and relic sub-shelf permafrost. The gas hydrate structure is only stable at sufficiently low temperature and high pressure, and may therefore collapse under changing climatic conditions. If a temperature rise or pressure drop (e.g. through falling sea level) is effective enough to dissociate hydrate deposits, methane (the most common gas component in hydrates and a potent greenhouse gas) is released from the hydrate structure and may eventually enter into the atmosphere. This may generate a positive feedback effect, as resulting enhanced greenhouse gas levels would additionally warm the atmosphere and hence maintain or reinforce hydrate dissociation. The significance of this mechanism has been debated over the past decades, often within the framework of geologically rapid Quaternary climatic oscillations and present-day climate warming. An extensive set of studies has addressed the climate-sensitivity of gas hydrate reservoirs in various study areas and geological settings, and by means of various approaches. No real consensus has yet been reached on the matter. In this study, we seek to evaluate the sensitivity of gas hydrate reservoirs to changes in global climate from a more general perspective, by firstly reviewing the available literature, and secondly developing a new numerical model to quantify gas hydrate destabilization under changing environmental conditions. Qualities of the model include the wide applicability to both marine and permafrost-related hydrate reservoirs and the integrative approach, combining existing hydrate formation models with a dissocation model that accounts for the consumption of latent heat during hydrate dissociation. To determine which settings are most vulnerable, and to acquire insight into the extent, fashion and rates of hydrate dissociation, we apply the model to four distinct types of hydrate reservoirs across a hypothetic high-latitude continental margin under two specific cases of climate change: the last deglaciation following the Last Glacial Maximum and present-day climate warming. The simulations indicate that hydrates on the upper continental slope and in association with thin, sub-shelf permafrost are most sensitive to the imposed climatic variations, whereas deepwater and onshore permafrost-related reservoirs react in a more stable way. However, the deep (i.e. at several tens to hundreds of meters subsurface depth) stratigraphic-type hydrates considered in this study constitute by far the largest fraction of the global gas hydrate volume, but dissociate on slow timescales of thousands to hundreds of thousands of years, even in the most sensitive environments. In contrast, shallow (i.e. at, or a few meters below the surface or seafloor) structural-type hydrates are able to respond to climatic variations on sub-millennial timescales, but the volumes of gas they may release are probably insignificant to the global carbon cycle and climate. Quaternary and present-day climate change do affect the stability of gas hydrate reservoirs, but at long timescales where hydrate volumes are large, and on short timescales where hydrate volumes are small. Consequently, gas hydrates dissociate to an extent that is too small or at a pace that is too slow to create a strong positive feedback effect. While the release of methane from the disintegration of gas hydrates is observed on different margins today, it is not likely to have played a leading role in Quaternary climatic variations or to become a significant process in the coming centuries as a result of present-day rising temperatures.
Published: 2017
Full Text: View/download PDF

45. Introducing global peat-specific temperature and pH calibrations based on brGDGT bacterial lipids

Author: Angela V. Gallego-Sala, Mariusz Gałka, Frank M. Chambers, E.N. Honorio Coronado, Sarah J. Feakins, Fatima Laggoun-Défarge, Paul D.M. Hughes, Erin L McClymont, Mari Könönen, Rob Marchant, Mariusz Lamentowicz, Yanhong Zheng, A. D. Cohen, Ali Pourmand, Xabier Pontevedra-Pombal, Arnaud Huguet, Dennis Del Castillo Torres, Jerome Blewett, Richard D. Pancost, Camilo Ponton, F. De Vleeschouwer, A. M. Rizzuti, Matthew J. Amesbury, Richard P. Evershed, M. A. Burrows, Laure Gandois, Richard Bindler, Outi Lähteenoja, Gordon N. Inglis, Judith Schellekens, Harald Biester, Patrick G. Hatcher, Line Rochefort, Bernhard David A Naafs, D. M. Gray, Organic Geochemistry Unit - OGU (Bristol, United Kingdom), University of Bristol [Bristol], Cabot Institute, State Key Laboratory of Continental Dynamics, Department of Geology, Northwestern Polytechnical University [Xi'an] (NPU), Geography, College of Life and Environmental Sciences, University of Exeter, Institut für Umweltgeochemie, Umeå University, Australian National University (ANU), Instituto de Investigaciones de la Amazonía Peruana (IIAP), Centre for Environmental Change and Quaternary Research, University of Gloucestershire (Cheltenham, GB), Department of Earth and Ocean Sciences [Columbia], University of South Carolina [Columbia], Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), 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)-Centre National de la Recherche Scientifique (CNRS), Pinelands Field Station, Rutgers University System (Rutgers), Department of Chemistry and Biochemistry Norfolk, Old Dominion University [Norfolk] (ODU), Palaeoecology Laboratory, University of Southampton, Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), Université Pierre et Marie Curie - Paris 6 (UPMC)-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), Department of Forest Sciences [Helsinki], Faculty of Agriculture and Forestry [Helsinki], University of Helsinki-University of Helsinki, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Biogéosystèmes Continentaux - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Department of Biology, University of Turku, University of Turku, University of York [York, UK], Departamento de Edafoloxía e Química Agrícola, Universidade de Santiago de Compostela [Spain] (USC ), Department of Earth Sciences [USC Los Angeles], University of Southern California (USC), Division of Marine Geology & Geophysics, University of Miami, University of Miami [Coral Gables], Department of Chemistry, Claflin University, Claflin University, Peatland Ecology Research Group, Centre for Northern Studies - Université Laval, Department of Soil Science, University of São Paulo, University of São Paulo (USP), ANR-2011-JS56-006-01 'PARAD'CNPq project 482815/2011-6, ANR-11-LABX-0010,DRIIHM / IRDHEI,Dispositif de recherche interdisciplinaire sur les Interactions Hommes-Milieux(2011), European Project: 340923,EC:FP7:ERC,ERC-2013-ADG,TGRES(2014), Department of Forest Sciences, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-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)-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 Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université Pierre et Marie Curie - Paris 6 (UPMC)-École Pratique des Hautes Études (EPHE), Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Universidade de São Paulo = University of São Paulo (USP), Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)
Subjects: 1171 Geosciences, Peat, Peatland, 010504 meteorology & atmospheric sciences, MARINE-SEDIMENTS, ta1172, BRANCHED GDGTS, ta1171, 010502 geochemistry & geophysics, 01 natural sciences, TIBETAN PLATEAU, Degree (temperature), Geochemistry and Petrology, CLIMATE VARIABILITY, Soil pH, Calibration, Organic matter, LATE HOLOCENE, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, 1172 Environmental sciences, 0105 earth and related environmental sciences, chemistry.chemical_classification, Hydrology, GDGT, GE, FRENCH PEATLAND, WESTERN-EUROPE, MEMBRANE-LIPIDS, Biomarker, 15. Life on land, calibration, ORGANIC-MATTER, lignite, chemistry, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental chemistry, Soil water, DIALKYL GLYCEROL TETRAETHERS, Environmental science, biomarker, peatland
Abstract: Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (-8 to 27 degrees C) and pH (3-8) range and present the first peat-specific brGDGT-based temperature and pH calibrations. Our results demonstrate that the degree of cyclisation of brGDGTs in peat is positively correlated with pH, pH = 2.49 x CBTpeat + 8.07 (n = 51, R-2 = 0.58, RMSE = 0.8) and the degree of methylation of brGDGTs is positively correlated with MAAT, MAAT(peat) (degrees C) = 52.18 x MBT'(5me) - 23.05 (n = 96, R-2 = 0.76, RMSE = 4.7 degrees C). These peat-specific calibrations are distinct from the available mineral soil calibrations. In light of the error in the temperature calibration (similar to 4.7 degrees C), we urge caution in any application to reconstruct late Holocene climate variability, where the climatic signals are relatively small, and the duration of excursions could be brief. Instead, these proxies are well-suited to reconstruct large amplitude, longer-term shifts in climate such as deglacial transitions. Indeed, when applied to a peat deposit spanning the late glacial period (similar to 15.2 kyr), we demonstrate that MAAT(peat) yields absolute temperatures and relative temperature changes that are consistent with those from other proxies. In addition, the application of MAAT(peat) to fossil peat (i.e. lignites) has the potential to reconstruct terrestrial climate during the Cenozoic. We conclude that there is clear potential to use brGDGTs in peats and lignites to reconstruct past terrestrial climate. (C) 2017 The Authors. Published by Elsevier Ltd.
Published: 2017
Full Text: View/download PDF

46. Atlantic forcing of Western Mediterranean winter rain minima during the last 12,000 years

Author: Abdeslam Mikdad, Birgit Schneider, Michael Strupler, Thomas C. Brachert, Christoph Zielhofer, Najib El Hamouti, Jens Bussmann, Sébastien Joannin, Steffen Mischke, Marc De Batist, Rik Tjallingii, Jennifer Campbell, Andreas Stele, Tobias Lauer, William J. Fletcher, Annett Junginger, Katrin Spitzer, Renard Centre of Marine Geology (RCMG), Universiteit Gent, Institut des Sciences de l'Evolution de Montpellier ( ISEM ), Université de Montpellier ( UM ) -Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique ( CNRS ), Centre National de la Recherche Scientifique ( CNRS ), German Research Centre for Geosciences - Helmholtz-Centre Potsdam ( GFZ ), 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 ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Universiteit Gent = Ghent University [Belgium] (UGENT), 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)-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), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), 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), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), 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), 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)
Subjects: Mediterranean climate, Western Mediterranean, Archeology, YOUNGER DRYAS, 010504 meteorology & atmospheric sciences, MIDDLE ATLAS, 01 natural sciences, [SHS]Humanities and Social Sciences, [ SDE ] Environmental Sciences, Ostracod, FIRE ACTIVITY, Meltwater, Holocene, ComputingMilieux_MISCELLANEOUS, Global and Planetary Change, North Atlantic Oscillation (NAO), biology, SOUTHERN SPAIN, Winter rain minima, Geology, Lake sediments, Morocco, Oceanography, [SDE]Environmental Sciences, Atlantic forcing, [ SDU ] Sciences of the Universe [physics], 010506 paleontology, AFRICAN HUMID PERIOD, VEGETATION DYNAMICS, Solar forcing, SURFACE-TEMPERATURE, [ SHS ] Humanities and Social Sciences, medicine, Younger Dryas, Air mass, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, LATE QUATERNARY, Seasonality, 15. Life on land, Radiative forcing, biology.organism_classification, medicine.disease, HOLOCENE CLIMATE VARIABILITY, NORTH-ATLANTIC, 13. Climate action, [SDU]Sciences of the Universe [physics], Earth and Environmental Sciences
Abstract: The limited availability of high-resolution continuous archives, insufficient chronological control, and complex hydro-climatic forcing mechanisms lead to many uncertainties in palaeo-hydrological reconstructions for the Western Mediterranean. In this study we present a newly recovered 19.63 m long core from Lake Sidi Ali in the North African Middle Atlas, a transition zone of Atlantic, Western Mediterranean and Saharan air mass trajectories. With a multi-proxy approach based on magnetic susceptibility, carbonate and total organic C content, core-scanning and quantitative XRF, stable isotopes of ostracod shells, charcoal counts, Cedrus pollen abundance, and a first set of diatom data, we reconstruct Western Mediterranean hydro-climatic variability, seasonality and forcing mechanisms during the last 12,000 yr. A robust chronological model based on AMS 14 C dated pollen concentrates supports our high-resolution multi-proxy study. Long-term trends reveal low lake levels at the end of the Younger Dryas, during the mid-Holocene interval 6.6 to 5.4 cal ka BP, and during the last 3000 years. In contrast, lake levels are mostly high during the Early and Mid-Holocene. The record also shows sub-millennial- to centennial-scale decreases in Western Mediterranean winter rain at 11.4, 10.3, 9.2, 8.2, 7.2, 6.6, 6.0, 5.4, 5.0, 4.4, 3.5, 2.9, 2.2, 1.9, 1.7, 1.5, 1.0, 0.7, and 0.2 cal ka BP. Early Holocene winter rain minima are in phase with cooling events and millennial-scale meltwater discharges in the sub-polar North Atlantic. Our proxy parameters do not show so far a clear impact of Saharan air masses on Mediterranean hydro-climate in North Africa. However, a significant hydro-climatic shift at the end of the African Humid Period (∼5 ka) indicates a change in climate forcing mechanisms. The Late Holocene climate variability in the Middle Atlas features a multi-centennial-scale NAO-type pattern, with Atlantic cooling and Western Mediterranean winter rain maxima generally associated with solar minima.
Published: 2017
Full Text: View/download PDF

47. Enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands: A sink for atmospheric CO2

Author: Guy Munhoven, Peter D. Clift, Wentao Ma, Jie Huang, Shiming Wan, Debo Zhao, Yinxi Wang, Jin Zhang, Niels Hovius, Christian France-Lanord, Guoliang Zhang, Tiegang Li, Anchun Li, Zhifang Xiong, Zhaojie Yu, State Key Laboratory of Marine Geology [Shanghai], Tongji University, Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, USA, Louisiana State University (LSU), School of Geography Science, Nanjing Normal University, Nanjing 210023, China, Nanjing Normal University (NNU), Institute of Oceanology [China], Department of Earth Sciences [Cambridge, UK], University of Cambridge [UK] (CAM), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), 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), Center of Modern Analysis, Nanjing University, 210093, China, Nanjing University (NJU), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Marine Sedimentology and Environmental Geology, State Oceanic Administration (SOA), and Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Climate change, Sediment, Weathering, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Silicate, chemistry.chemical_compound, Oceanography, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, Geochemistry and Petrology, Silicate minerals, Subaerial, Interglacial, 14. Life underwater, Glacial period, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Atmospheric CO2 and global climate are closely coupled. Since 800 ka CO2 concentrations have been up to 50% higher during interglacial compared to glacial periods. Because of its dependence on temperature, humidity, and erosion rates, chemical weathering of exposed silicate minerals was suggested to have dampened these cyclic variations of atmospheric composition. Cooler and drier conditions and lower non-glacial erosion rates suppressed in situ chemical weathering rates during glacial periods. However, using systematic variations in major element geochemistry, Sr–Nd isotopes and clay mineral records from Ocean Drilling Program Sites 1143 and 1144 in the South China Sea spanning the last 1.1 Ma, we show that sediment deposited during glacial periods was more weathered than sediment delivered during interglacials. We attribute this to subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands. Our estimates suggest that enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands can account for ∼9% of the carbon dioxide removed from the atmosphere during the glacial and thus represent a significant part of the observed glacial–interglacial variation of ∼80 ppmv. As a result, if similar magnitudes can be identified in other tropical shelf-slope systems, the effects of increased sediment exposure and subsequent silicate weathering during lowstands could have potentially enhanced the drawdown of atmospheric CO2 during cold stages of the Quaternary. This in turn would have caused an intensification of glacial cycles.
Published: 2017
Full Text: View/download PDF

48. PALEOLIMNOLOGY OF LAKE HAMOUN (E IRAN): IMPLICATION FOR PAST CLIMATE CHANGES AND POSSIBLE IMPACTS ON HUMAN SETTLEMENTS

Author: Morteza Djamali, Reza Moussavi-Harami, Mohammad Ali Hamzeh, Mohammad H. Mahmudy-Gharaie, Hamid Alizadeh-Lahijani, Abdolmajid Naderi-Beni, Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UMR237-Aix Marseille Université (AMU)-Avignon Université (AU), Ferdowsi University of Mashhad (FUM), Marine Geology Department, Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), and Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS)
Subjects: Hydrology, 010506 paleontology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Drainage basin, Paleontology, Westerlies, Structural basin, 01 natural sciences, Paleolimnology, 13. Climate action, Deglaciation, Glacial period, Physical geography, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Quaternary, Ecology, Evolution, Behavior and Systematics, Holocene, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Environmental changes since the late deglaciation are reconstructed from the sediment of Lake Hamoun. Lake Hamoun is located at the border of Iran and Afghanistan where inflowing rivers originate from the drainage basins of SW Hindu Kush Mountains and westernmost Himalaya. The lake has experienced a complex hydrological history during the late Quaternary due to climatic changes. Geochemical, sedimentological, and paleontological proxies as well as geomorphological data were used to investigate environmental changes of the lake. The results demonstrate that since the late glacial, the basin has directly and/or indirectly received its moisture from various climatic systems. During the early Holocene, both the Indian summer monsoon (ISM) and the mid-latitude westerlies (MLW) intensified and consequently the basin received higher precipitation. This interpretation is supported by higher content of total organic matter (mean: 8.2%), finer-grained sediments with low delta O-18 values (mean: -3.5%), as well as rich fossil content. Lower organic matter content (,\textless 5%), higher magnetic susceptibility values (5.8-10x10(-4) SI unit), and coarser-grained sediments with no shell fragments support the dominance of an arid environment during the early-mid Holocene. The results of stable isotopes suggest weakening of ISM and intensification of MLW during the mid-late Holocene in the study area, when Bronze Age civilizations emerged in the Sistan Basin. In the late Holocene, lake levels experienced more severe fluctuations due to variations in the MLW. Shifts in settlement areas seen in the archaeological record may thus have been a response to climatic changes.
Published: 2016
Full Text: View/download PDF

49. Environmental quality assessment of reservoirs impacted by Hg from chlor-alkali technologies: case study of a recovery

Author: Rebecca Beauvais-Flück, Jean-Luc Loizeau, Vera I. Slaveykova, Perrine Dranguet, Costin Ungureanu, Mariana Zazu, Claudia Cosio, Irina Catianis, Séverine Le Faucheur, Dan Vasiliu, Viorel Gheorghe Ungureanu, Forel Institute, University of Geneva [Switzerland], National Institute for Marine Geology and Geo-ecology (GeoEcoMar ), and Reims Champagne-Ardenne, BU de
Subjects: Aquatic Organisms, Geologic Sediments, 010504 meteorology & atmospheric sciences, Health, Toxicology and Mutagenesis, Legacy pollution, Alkalies, 010501 environmental sciences, 01 natural sciences, Eating, Soil, chemistry.chemical_compound, ddc:550, Methylmercury, ComputingMilieux_MISCELLANEOUS, media_common, Risk assessment, ddc:333.7-333.9, [SDV.TOX.ECO] Life Sciences [q-bio]/Toxicology/Ecotoxicology, Fishes, General Medicine, Environmental exposure, Hydrogen-Ion Concentration, Methylmercury Compounds, Pollution, 6. Clean water, Environmental chemistry, [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology, Environmental Monitoring, media_common.quotation_subject, chemistry.chemical_element, Rivers, Animals, Humans, Environmental Chemistry, Ecotoxicology, Environmental quality, 0105 earth and related environmental sciences, Chlor-alkali plant, Romania, Environmental Exposure, Mercury, Mercury (element), chemistry, 13. Climate action, Reservoirs, Soil water, Environmental science, Ecotoxicity, Water Pollutants, Chemical
Abstract: Mercury (Hg) pollution legacy of chlor-alkali plants will be an important issue in the next decades with the planned phase out of Hg-based electrodes by 2025 within the Minamata convention. In such a context, the present study aimed to examine the extent of Hg contamination in the reservoirs surrounding the Oltchim plant and to evaluate the possible improvement of the environmental quality since the closure of its chlor-alkali unit. This plant is the largest chlor-alkali plant in Romania, which partly switched to Hg-free technolo- gy in 1999 and definitely stopped the use of Hg electrolysis in May 2012. Total Hg (THg) and methylmercury (CH3Hg) concentrations were found to decrease in the surface waters and sediments of the reservoirs receiving the effluents of the chlor-alkali platform since the closure of Hg units. Hence, calculated risk quotients (RQ) indicated no adverse effect of Hg for aquatic organisms from the ambient water exposure. RQ of Hg in sediments were mostly all higher than 1, showing important risks for benthic organisms. However, ecotoxicity testing of water and sediments suggest possible impact of other contaminants and their mixtures. Hg hotspots were found in soils around the platform with RQ values much higher than 1. Finally, THg and CH3Hg concentrations in fish were below the food safety limit set by the WHO, which contrasts with previous measurements made in 2007 revealing that 92 % of the studied fish were of high risk of consumption. Discontinuing the use of Hg electrodes greatly improved the surrounding environment of chlor-alkali plants within the following years and led to the decrease environmental exposure to Hg through fish consumption. However, sediment and soil still remained highly contaminated and problematic for the river reservoir management. The results of this ecological risk assessment study have important implications for the evaluation of the benefits as well as limits of the Minamata Convention implementation.
Published: 2016

50. Climate variability across the last deglaciation in NW Iberia and its margin

Author: Antje H L Voelker, Sébastien Zaragosi, E. Michel, Teresa Rodrigues, Josette Duprat, Linda Rossignol, Filipa Naughton, Fatima F Abrantes, Stéphanie Desprat, Emilia Salgueiro, M. F. Sánchez Goñi, Susana Costas, Universidade Federal de São Paulo (UNIFESP), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux ( 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 ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherche en Gestion des Organisations ( CReGO ), Université de Franche-Comté ( UFC ) -Université de Bourgogne ( UB ), 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 ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Environnements et Paléoenvironnements OCéaniques ( EPOC ), Antarctic Climate and Ecosystems Cooperative Research Center ( ACE-CRC ), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung ( AWI ), Marine Geology Department, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (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), Environnements et Paléoenvironnements OCéaniques (EPOC), Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Federal University of Sao Paulo (Unifesp), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Polar front, [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, 010504 meteorology & atmospheric sciences, Oldest Dryas, Westerlies, 15. Life on land, 01 natural sciences, Allerød oscillation, Bølling-Allerød, Oceanography, 13. Climate action, Deglaciation, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Stadial, Younger Dryas, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: The direct comparison between marine and terrestrial data from the NW Iberian margin, core MD03-2697, allows us to accurately evaluate, without chronological ambiguity, the vegetation response to North Atlantic climate events across the last deglaciation. Comparison of MD03-2697 data with other marine and terrestrial records from a vast area stretching from the Azores to western (W) France, Iberia and its margin, the W Mediterranean and NW Africa reveals the importance of enhanced winter North Atlantic westerlies episodes in driving a heterogeneous regional climatic signal during particular events of the last deglaciation. Heinrich Stadial 1 (HS1)/Oldest Dryas is a complex event marked by three synchronous main phases (a: extremely cold/relatively wet; b: cool/dry; c: relatively warmer/increasing moisture availability) in regions directly influenced by the North Atlantic while it is characterized by a single phase (cold and dry) in most inland and high altitude areas. Changes in the strength and position of North Atlantic westerlies could explain the variability in moisture during HS1 from W Pyrenees to W Mediterranean. The Bolling-Allerod (B-A) event is marked by a synchronous progressive increase of ocean and atmospheric temperatures and precipitation from the Bolling to the Allerod in W Iberia and W Pyrenees contrasting with the Greenland temperature pattern. Mid-to high latitudes thermal contrast and the gradual strengthening of the Atlantic Meridional Overturning Circulation (AMOC) triggered the continuing enhancement of westerlies, and moisture, along this period.Finally, the Younger Dryas (YD) Stadial is characterized by a land-ocean synchronous returning cold conditions (but not so cold as HS1) and, although dry conditions persisted during this period, extreme winter precipitation occurrences might have affected the most coastal areas of north and central W Iberia and Pyrenees. In contrast, dry conditions persisted during the YD in the western Mediterranean regions. The westerlies migrated further north following the displacement of the Polar Front during the deglaciation precluding the input of moisture in the W Mediterranean region, which persisted very dry during the YD Stadial. (C) 2016 Published by Elsevier Ltd. MAR/LA00015/2014; ANR-05-BLAN0310-01; ANR 2011 BSH3 0005
Published: 2016
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Journal

Database

Publisher

94 results on '"Marine Geology"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources