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12 results on '"International Continental Scientific Drilling Program"'

1. MagellanPlus Workshop: Mission-Specific Platform Approaches To Assessing Natural Hazards That Impact Society

Author

European Consortium for Ocean Research Drilling, International Continental Scientific Drilling Program, Daigle, Hugh, Duarte, João C., Fagereng, Ake, Paris, Raphaël, Persaud, Patricia, Gómez-García, Á. M., European Consortium for Ocean Research Drilling, International Continental Scientific Drilling Program, Daigle, Hugh, Duarte, João C., Fagereng, Ake, Paris, Raphaël, Persaud, Patricia, and Gómez-García, Á. M.

Abstract

Oceanic natural hazards pose threats to coastal communities worldwide. These include earthquakes, tsunamis, submarine landslide, volcanic eruptions, and tropical cyclones. Scientific ocean drilling can contribute to our understanding and assessment of these hazards through rapid response measurements of hazardous events, learning from past hazard records, and sub-seafloor monitoring and observation. With the impending retirement of the D/V JOIDES Resolution and operational limitations of the D/V Chikyu, it is important to consider other options for achieving scientific ocean drilling goals. We convened a workshop in Lisbon, Portugal, in July 2022 to identify locations where natural hazards, or preferably several different hazards, can be addressed with mission-specific platform (MSP) drilling, with a consideration of further location-based workshops. Participants split into three working groups to develop hypotheses surrounding climate and tropical cyclones, slope failure, and processes at active margins that can be tested with MSP drilling and can be addressed using the unique capabilities of these platforms. We produced 13 questions or hypotheses with recommendations on specific areas or locations for drilling. Our hope is that the results of this workshop will lay the groundwork for future pre-proposals.

Published
2023

2. Antarctic Environmental Change and Ice Sheet Evolution through the Miocene to Pliocene ¿ A perspective from the Ross Sea and George V to Wilkes Land Coasts

Author

European Commission, Ministerio de Economía, Industria y Competitividad (España), International Continental Scientific Drilling Program, Escutia, Carlota, Levy, Richard H., Dolan, A. M., Gasson, E. G. H., McKay, Robert M., Naish, Timothy R., Patterson, M. O., Pérez, L. F., Shevenell, A. E., van de Flierdt, Tina, Dickinson, W., Kowalewski, D. E., Meyers, S. R., Ohneiser, Christian, Sangiorgi, F., European Commission, Ministerio de Economía, Industria y Competitividad (España), International Continental Scientific Drilling Program, Escutia, Carlota, Levy, Richard H., Dolan, A. M., Gasson, E. G. H., McKay, Robert M., Naish, Timothy R., Patterson, M. O., Pérez, L. F., Shevenell, A. E., van de Flierdt, Tina, Dickinson, W., Kowalewski, D. E., Meyers, S. R., Ohneiser, Christian, and Sangiorgi, F.

Published
2022

3. Ship-board determination of whole-rock (ultra-)trace element concentrations by laser ablation-inductively coupled plasma mass spectrometry analysis of pressed powder pellets aboard the D/V Chikyu

Author

International Continental Scientific Drilling Program, German Research Foundation, Japan Society for the Promotion of Science, Centre National de la Recherche Scientifique (France), Rospabé, Mathieu, Kourim, Fatma, Tamura, Akihiro, Takazawa, Eiichi, Giampouras, Manolis, Chatterjee, Sayantani, Ishii, Keisuke, Cooper, Matthew J., Godard, Marguerite, Carter, Elliot, Abe, Natsue, Moe, Kyaw, Teagle, D. A. H., International Continental Scientific Drilling Program, German Research Foundation, Japan Society for the Promotion of Science, Centre National de la Recherche Scientifique (France), Rospabé, Mathieu, Kourim, Fatma, Tamura, Akihiro, Takazawa, Eiichi, Giampouras, Manolis, Chatterjee, Sayantani, Ishii, Keisuke, Cooper, Matthew J., Godard, Marguerite, Carter, Elliot, Abe, Natsue, Moe, Kyaw, and Teagle, D. A. H.

Abstract

The Oman Drilling Project (OmanDP), performed under the International Continental Scientific Drilling Program (ICDP), is an international scientific research project that undertook drilling at a range of sites in the Semail ophiolite (Oman) to collect core samples spanning the stratigraphy of the ophiolite, from the upper oceanic crust down to the basal thrust. The cores were logged to International Ocean Discovery Program (IODP) standards aboard the D/V Chikyu. During ChikyuOman2018 Leg 3 (July-August 2018), participants described cores from the crust-mantle transition (CM) sites. The main rock types recovered at these sites were gabbros, dunites and harzburgites, rocks typically forming the base of the oceanic crust and the shallow mantle beneath present-day spreading centres. In addition to the core description, selected samples were analysed by X-ray fluorescence spectrometry (XRF) for their chemical compositions, including major, minor and some trace elements. To complement these standard procedures, we developed new approaches to measure ultra-trace element concentrations using a procedure adapted from previous works to prepare fine-grained pressed powder pellets coupled with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis using instrumentation aboard the D/V Chikyu. First, three (ultra)mafic reference materials were investigated to test and validate our procedure (BHVO-2, BIR-1a and JP-1), and then the procedure was applied to a selection of gabbro and dunite samples from the CM cores to explore the limitations of the method in its current stage of development. The obtained results are in good agreement with preferred values for the reference materials and with subsequent solution replicate analyses of the same samples performed in shore-based laboratories following Leg 3 for the CM samples. We describe this procedure for the determination of 37 minor and (ultra-)trace elements (transition elements and Ga, Li and Large-Ion Lit

Published
2022

4. Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

Author

International Continental Scientific Drilling Program, Istituto Nazionale di Geofisica e Vulcanologia, Jurado, Maria José [0000-0001-8165-2729], Somma, Renato, Blessent, Daniela, Raymond, Jasmin, Constance, Madeline, Cotton, Lucy, De Natale, Giuseppe, Fedele, Alessandro, Jurado, Maria José, Marcia, Kirsten, Miranda, Mafalda, Troise, Claudia, Wiersberg, Thomas, International Continental Scientific Drilling Program, Istituto Nazionale di Geofisica e Vulcanologia, Jurado, Maria José [0000-0001-8165-2729], Somma, Renato, Blessent, Daniela, Raymond, Jasmin, Constance, Madeline, Cotton, Lucy, De Natale, Giuseppe, Fedele, Alessandro, Jurado, Maria José, Marcia, Kirsten, Miranda, Mafalda, Troise, Claudia, and Wiersberg, Thomas

Abstract

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development.

Published
2021

5. Ice loss from the East Antarctic Ice Sheet during late Pleistocene interglacials

Author

International Continental Scientific Drilling Program, National Science Foundation (US), Australian Research Council, Ministerio de Ciencia e Innovación (España), Wilson, David J., Bertram, Raquel A., Needham, Emma F., van de Flierdt, Tina, Welsh, Kevin J., McKay, Robert M., Mazumder, Anannya, Riesselman, Christina R., Jimenez Espejo, Francisco Jose, Escutia, Carlota, International Continental Scientific Drilling Program, National Science Foundation (US), Australian Research Council, Ministerio de Ciencia e Innovación (España), Wilson, David J., Bertram, Raquel A., Needham, Emma F., van de Flierdt, Tina, Welsh, Kevin J., McKay, Robert M., Mazumder, Anannya, Riesselman, Christina R., Jimenez Espejo, Francisco Jose, and Escutia, Carlota

Abstract

Understanding ice sheet behaviour in the geological past is essential for evaluating the role of the cryosphere in the climate system and for projecting rates and magnitudes of sea level rise in future warming scenarios. Although both geological data and ice sheet models indicate that marine-based sectors of the East Antarctic Ice Sheet were unstable during Pliocene warm intervals, the ice sheet dynamics during late Pleistocene interglacial intervals are highly uncertain. Here we provide evidence from marine sedimentological and geochemical records for ice margin retreat or thinning in the vicinity of the Wilkes Subglacial Basin of East Antarctica during warm late Pleistocene interglacial intervals. The most extreme changes in sediment provenance, recording changes in the locus of glacial erosion, occurred during marine isotope stages 5, 9, and 11, when Antarctic air temperatures were at least two degrees Celsius warmer than pre-industrial temperatures for 2,500 years or more. Hence, our study indicates a close link between extended Antarctic warmth and ice loss from the Wilkes Subglacial Basin, providing ice-proximal data to support a contribution to sea level from a reduced East Antarctic Ice Sheet during warm interglacial intervals. While the behaviour of other regions of the East Antarctic Ice Sheet remains to be assessed, it appears that modest future warming may be sufficient to cause ice loss from the Wilkes Subglacial Basin.

Published
2018

6. Wildfire activity enhanced during phases of maximum orbital eccentricity and precessional forcing in the Early Jurassic

Author

Micha Ruhl, Luke Mander, Jean-François Deconinck, Sarah J. Baker, Stephen P. Hesselbo, Claire M. Belcher, Teuntje P. Hollaar, wildFIRE Lab, Hatherly Laboratories, University of Exeter, Camborne School of Mines (CSM-UE), Environment and Sustainability Institute [Penryn, UK], Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Department of Environment, Earth and Ecosystems [Open University], The Open University [Milton Keynes] (OU), Department of Geology [Dublin], Trinity College Dublin, Funded by the Natural Environment Research Council (NERC) (grant number NE/N018508/1), the International Continental Scientific Drilling Program (ICDP), the University of Exeter, and NERC (NE/L501669/1)., and Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement

Subjects
Biogeochemical cycle, QE1-996.5, 010504 meteorology & atmospheric sciences, Fire regime, Orbital forcing, Geology, Vegetation, Forcing (mathematics), 15. Life on land, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Palynofacies, Environmental sciences, 13. Climate action, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, General Earth and Planetary Sciences, Environmental science, Sedimentary rock, GE1-350, Water cycle, 0105 earth and related environmental sciences, General Environmental Science
Abstract

Fire regimes are changing due to both anthropogenic climatic drivers and vegetation management challenges, making it difficult to determine how climate alone might influence wildfire activity. Earth has been subject to natural-background climate variability throughout its past due to variations in Earth’s orbital parameters (Milkankovitch cycles), which provides an opportunity to assess climate-only driven variations in wildfire. Here we present a 350,000 yr long record of fossil charcoal from mid-latitude (~35°N) Jurassic sedimentary rocks. These results are coupled to estimates of variations in the hydrological cycle using clay mineral, palynofacies and elemental analyses, and lithological and biogeochemical signatures. We show that fire activity strongly increased during extreme seasonal contrast (monsoonal climate), which has been linked to maximal precessional forcing (boreal summer in perihelion) (21,000 yr cycles), and we hypothesize that long eccentricity modulation further enhances precession-forced fire activity. Increased fire activity in the Early Jurassic is related to changes in the hydrological cycle driven by enhanced seasonality due to orbital forcing, according to a mid-latitude sedimentary charcoal record spanning 350,000 years.

Published
2021

7. Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

Author

Giuseppe De Natale, Maria José Jurado, Mafalda Alexandra Miranda, Thomas Wiersberg, Claudia Troise, Lucy Cotton, Alessandro Fedele, Daniela Blessent, Madeline Constance, Renato Somma, Kirsten Marcia, Jasmin Raymond, International Continental Scientific Drilling Program, Istituto Nazionale di Geofisica e Vulcanologia, and Jurado, Maria José

Subjects
Geothermal power, Technology, Control and Optimization, 020209 energy, Earth science, Unconventional geothermal resources, Energy Engineering and Power Technology, 02 engineering and technology, 010502 geochemistry & geophysics, 01 natural sciences, campi flegrei, Geothermal drilling, geothermal, geothermal energies, 0202 electrical engineering, electronic engineering, information engineering, caldera, Electrical and Electronic Engineering, Engineering (miscellaneous), Geothermal gradient, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Renewable Energy, Sustainability and the Environment, business.industry, Scientific drilling, Geothermal energy, Communities, Drilling, Building and Construction, Unconventional oil, Sedimentary basin, EGS, Enhanced Geothermal Systems, Renewable energy, business, Geology, Energy (miscellaneous)
Abstract

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development., This research was co-funded by ICDP consortium and INGV for the CFDDP. Grant number CFDDP 05-2008.

Published
2021

8. Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

Author

Somma, Renato, Blessent, Daniela, Raymond, Jasmin, Constance, Madeline, Cotton, Lucy, De Natale, Giuseppe, Fedele, Alessandro, Jurado, Maria José, Marcia, Kirsten, Miranda, Mafalda, Troise, Claudia, Wiersberg, Thomas, International Continental Scientific Drilling Program, Istituto Nazionale di Geofisica e Vulcanologia, and Jurado, Maria José [0000-0001-8165-2729]

Subjects
Geothermal drilling, Unconventional geothermal resources, Communities, caldera, Enhanced Geothermal Systems
Abstract

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development. This research was co-funded by ICDP consortium and INGV for the CFDDP. Grant number CFDDP 05-2008.

Published
2021

9. New fossil genus and new extant species of diatoms (Stephanodiscaceae, Bacillariophyceae) from Pleistocene sediments in the Neotropics (Guatemala, Central America): adaptation to a changing environment?

Author

Jean-Charles Mazur, Alain Tonetto, Sandrine Conrod, Christine Paillès, Florence Sylvestre, PAILLES, Christine, 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), 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), Aix Marseille Université (AMU), US National Science Foundation (ATM-0502030), International Continental Scientific Drilling Program, Swiss Federal Institute of Technology, and Swiss National Science Foundation

Subjects
Pleistocene, Ochrophyta, 020209 energy, Guatemala, Thalassiosirales, 0211 other engineering and technologies, 02 engineering and technology, Ecological succession, genus, Paleontology, Extant taxon, Genus, lcsh:Botany, 021105 building & construction, lcsh:Zoology, 0202 electrical engineering, electronic engineering, information engineering, lcsh:QL1-991, Ecology, Evolution, Behavior and Systematics, Taxonomy, Chromista, Bacillariophyceae, biology, Diatom, Discostella gabinii, Biodiversity, biology.organism_classification, 6. Clean water, diatom, lcsh:QK1-989, Stephanodiscaceae, [SDE.BE] Environmental Sciences/Biodiversity and Ecology, Taxon, Adaptation, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Cyclocostis rolfii, Geology
Abstract

Several taxa of Stephanodiscaceae were found in the upper section of Pleistocene sediments from Lake Petén-Itzá (Guatemala). A new fossil genus Cyclocostis Paillès gen. nov. and new extant species Discostella gabinii Paillès & Sylvestre sp. nov. are described. Cyclocostis gen. nov. is characterized by a strongly tangentially undulated valve surface, coarse unequal striation reaching a central punctum in the valve center, an absence of central lamina and domed criba, widely open alveoli with one median recessed costa bearing marginal fultoportulae and a single rimoportula all within a ring. A single valve face fultoportula is present on the raised part of the valve opposite the rimoportula. Differences relative to similar genera and the delimitation of a new genus are discussed. Discostella gabinii sp. nov. is distinguished by circular and flat valves, a small central area bearing 5 to > 30 scattered large areolae giving a colliculate appearance, medium-sized alveoli, marginal fultoportulae on every 4–5th costa, a single rimoportula and internally smooth valve center. Differences to similar taxa in the genus Discostella are discussed. The succession of the species of Cyclotella, Discostella and Cyclocostis gen. nov. in our record could represent eco-phenotypic responses to particular environmental stress / change.

Published
2020

10. Climatic and sea‐level control of Jurassic (Pliensbachian) clay mineral sedimentation in the Cardigan Bay Basin, Llanbedr (Mochras Farm) borehole, Wales

Author

Jean-François Deconinck, Pierre Pellenard, Stephen P. Hesselbo, Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, Camborne School of Mines (CSM-UE), University of Exeter, Environment and Sustainability Institute [Penryn, UK], Funding from the International Continental Scientific Drilling Program (ICDP) and the Natural Environment Research Council (NERC) (grant number NE/N018508/1)., and Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Stratigraphy, Early Jurassic, Borehole, Geochemistry, Pliensbachian, Geology, 15. Life on land, Structural basin, Sedimentation, 010502 geochemistry & geophysics, 01 natural sciences, palaeoclimate, Clay minerals, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, 14. Life underwater, clay sedimentation, Bay, Sea level, 0105 earth and related environmental sciences
Abstract

15 pages; International audience; Early Jurassic climate is characterized by alternating cold and warm periods highlighted by studies based notably on oxygen isotopes measured on belemnite guards and other marine invertebrate shells. These climatic changes include changes in the hydrological cycle, and consequently weathering and runoff conditions. In order to clarify the erosion and weathering conditions during the Pliensbachian, this study determined the mineralogical composition of the clay fraction of 132 samples taken from the entire stage drilled in the Llanbedr (Mochras Farm) borehole (Cardigan Bay Basin). The clay mineral assemblages are composed of various proportions of chlorite, illite, illite/smectite mixed‐layers (R1 I–S), smectite and kaolinite, with possibly occasional traces of berthierine. The occurrence of abundant smectite indicates that the maximum burial temperature never exceeded 70°C. Consequently, clay minerals are considered mainly detrital, and their fluctuations likely reflect environmental changes. The variations in the proportions of smectite and kaolinite are opposite to each other. Kaolinite is particularly abundant at the base of the jamesoni Zone, in part coinciding with the δ13C negative excursion corresponding to the Sinemurian/Pliensbachian Boundary Event, and through the davoei Zone, whilst smectite is abundant in the upper part of jamesoni and base of ibex zones and through the subnodosus/gibbosus subzones of the margaritatus Zone. The kaolinite‐rich intervals reflect an intensification of hydrolysis and an acceleration of the hydrological cycle, while the smectite‐rich intervals indicate a more arid climate. The spinatum Zone is characterized by a distinct clay assemblage with abundant primary minerals, R1 I–S, kaolinite reworked from previously deposited sediments or from Palaeozoic rocks, and probably berthierine originating from contemporaneous ironstone‐generating environments of shallower waters. This mineralogical change by the end of the Pliensbachian likely reflects a transition from a dominant chemical weathering to a deeper physical erosion of the continent, probably related to a significant sea‐level fall consistent with a glacio‐eustatic origin.

Published
2019

11. Waxing and waning of forests: Late Quaternary biogeography of southeast Africa

Author

Anne-Marie Lézine, Sarah J. Ivory, Andrew S. Cohen, Annie Vincens, Ohio State University [Columbus] (OSU), Department of Geosciences [PennState], College of Earth and Mineral Sciences, Pennsylvania State University (Penn State), Penn State System-Penn State System-Pennsylvania State University (Penn State), Penn State System-Penn State System, Variabilité à long terme du climat de l'océan (VALCO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), 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), University of Arizona, US National Science Foundation–Earth System History Program. Grant Number: EAR‐0602350 International Continental Scientific Drilling Program National Science Foundation Graduate Research Fellowship. Grant Number: 2009078688, 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)-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), 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), 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)), 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)-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)), 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), 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
0106 biological sciences, 010504 meteorology & atmospheric sciences, Steppe, Climate Change, Biogeography, hydrology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forests, 010603 evolutionary biology, 01 natural sciences, palaeoclimate, Trees, Forest ecology, Tropical vegetation, Humans, Environmental Chemistry, biogeography, global change, 0105 earth and related environmental sciences, General Environmental Science, tropical forests, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, Gallery forest, Vegetation, 15. Life on land, Biological Evolution, Arid, Disturbance (ecology), 13. Climate action, palaeoenvironments, Lake Malawi, Africa
Abstract

International audience; African ecosystems are at great risk. Despite their ecological and economic importance, long‐standing ideas about African forest ecology and biogeography, such as the timing of changes in forest extent and the importance of disturbance, have been unable to be tested due to a lack of sufficiently long records. Here, we present the longest continuous terrestrial record of late Quaternary vegetation from southern Africa collected to date from a drill core from Lake Malawi covering the last ~600,000 years. Pollen analysis permits us to investigate changes in vegetation structure and composition over multiple climatic transitions. We observe nine phases of forest expansion and collapse related to regional hydroclimate change. The development of desert, steppe and grassland vegetation during arid periods is likely dynamically linked to thresholds in regional hydrology associated with lake level and moisture recycling. Species composition of these dryland ecosystems varied greatly and is unlike the vegetation found at Malawi today, with assemblages suggesting strong Somali‐Masai affinities. Furthermore, nearly all semiarid assemblages contain low forest taxa abundances, suggesting that moist lowland gallery forests formed refugia along waterways during arid times. When the region was wet, forests were species‐rich and very high afromontane tree abundances suggest frequent widespread lowland colonization by modern high elevation trees. Furthermore, species composition varied little amongst forest phases until ~80 ka when disturbance tolerant tree taxa characteristic of the modern vegetation increased in abundance. The waxing and waning of forests has important implications for understanding the processes that control modern tropical vegetation biogeography as well as the environments of early humans across Africa. Finally, this work highlights the resilience of montane forests during previous warm intervals, which is relevant for future climate change; however, we point to a fundamental shift in disturbance regimes which are crucial for the structure and composition of modern East African landscapes.

Published
2018

12. Cyclotella petenensis and Cyclotella cassandrae, two new fossil diatoms from Pleistocene sediments of Lake Petén-Itzá, Guatemala, Central America

Author

Paillès, Christine, Pailles, Christine, Sylvestre, Florence, ESCOBAR, JAIME, Tonetto, Alain, RUSTIG, SYBILLE, Mazur, Jean-Charles, 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), Universidad del Norte, Smithsonian Tropical Research Institute, Aix-Marseille Université - Faculté des Sciences (AMU SCI), Aix Marseille Université (AMU), Institut für Chemie [Universität Potsdam] | Institute of Chemistry [University of Potsdam], University of Potsdam = Universität Potsdam, US National Science Foundation, International Continental Scientific Drilling Program, Swiss Federal Institute of Technology, Swiss National Science Foundation, Institute for Research and Development (IRD), 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 für Chemie, Universität Potsdam, 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 für Chemie [Potsdam]

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Pleistocene, Algae, Lake Petén-Itzá, Plant Science, 01 natural sciences, Paleontology, Genus, Discostella, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, biology, Diatom, biology.organism_classification, Guatemala, Diatom flora, Lake Peten-Itza, Taxon, ddc:540, Cyclotella, Institut für Chemie, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract

While analyzing the fossil diatom flora in one of the longest paleolimnological records (core PI-6) from Lake Petén-Itzá, lowland Guatemala, we encountered Aulacoseira Thwaites, Cyclotella (Kützing) and Discostella (Cleve & Grunow) Houk & Klee species appearing successively in the record. Among them, two new species that are assigned to the genus Cyclotella are described herein. Cyclotella petenensis sp. nov. is characterised by a coarse striation marked by a shadow line and a tangentially undulate central area with an arc of central fultoportulae. Cyclotella cassandrae sp. nov. has an elliptically shaped valve, coarse striae and a scattered ring of central fultoportulae in the central area. Classification and differences to similar taxa in the genus Cyclotella are discussed.

Published
2018

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