Search

Your search keyword '"European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)"' showing total 16 results
Start Over Author "European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)"
16 results on '"European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)"'

1. The evolutionary history of the Central Asian steppe-desert taxon Nitraria (Nitrariaceae) as revealed by integration of fossil pollen morphology and molecular data

Author

Amber Woutersen, Phillip E Jardine, Daniele Silvestro, Raul Giovanni Bogotá-Angel, Hong-Xiang Zhang, Niels Meijer, Johannes Bouchal, Natasha Barbolini, Guillaume Dupont-Nivet, Andreas Koutsodendris, Alexandre Antonelli, Carina Hoorn, Institute for Biodiversity and Ecosystem Dynamics (IBED), Westfälische Wilhelms-Universität Münster = University of Münster (WWU), Université de Fribourg = University of Fribourg (UNIFR), University of Gothenburg (GU), Universidad Distrital Francisco Jose de Caldas [Bogota], Chinese Academy of Sciences [Xi’an], Senckenberg Institute, University of Vienna [Vienna], Stockholm University, University of Bergen (UiB), 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), University of Potsdam = Universität Potsdam, Universität Heidelberg [Heidelberg] = Heidelberg University, Departement of Computer of Science University of Oxford, University of Oxford, Swiss National Science Foundation (SNSF) (PCEFP3_187012, FN-1749), Swedish Research Council, CAS President's International Fellowship Initiative (2018VBA0038), and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)

Subjects
desert -Eurasian steppe -light microscopy -phylogeny -SEM -Tibetan Plateau, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Plant Science, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Ecology, Evolution, Behavior and Systematics
Abstract

The transition from a greenhouse to an icehouse world at the Eocene-Oligocene Transition (EOT) coincided with a large decrease of pollen from the steppe-adapted genus Nitraria. This genus, now common along the Mediterranean coast, Asia and Australia, has a proposed coastal origin and a geographically widespread fossil record. Here we investigated the evolution, taxonomic diversity and morphological disparity of Nitraria throughout the Cenozoic by integrating extant taxa and fossil palynological morphotypes into a unified phylogenetic framework based on both DNA sequences and pollen morphological data. We present the oldest fossil pollen grain of Nitraria, at least 53 Myr old. This fossil was found in Central Asian deposits, providing new evidence for its origin in this area. We found that the EOT is an evolutionary bottleneck for Nitraria, coinciding with retreat of the proto-Paratethys Sea, a major global cooling event and a turnover in Central Asian steppe vegetation. We infer the crown age of modern Nitraria spp. to be significantly younger (Miocene) than previously estimated (Palaeocene). The diversity trajectory of Nitraria inferred from extant-only taxa differs markedly from one that also considers extinct taxa. Our study demonstrates it is therefore critical to apply an integrative approach to fully understand the plant evolutionary history of Nitrariaceae.

Published
2023

2. Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model

Author

X. P. Yuan, R. Jiao, G. Dupont‐Nivet, X. Shen, China University of Geosciences [Wuhan] (CUG), University of Victoria [Canada] (UVIC), 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), University of Potsdam = Universität Potsdam, National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing, 100085, China, National Natural Science Foundation of China (NSFC) 42073052, and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geophysics, General Earth and Planetary Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract

The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remains ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene or later in the Neogene. As the landscape evolution is controlled mainly by mountain uplift and surface processes, the present-day river profiles and the drainage basin geometries preserve important information that can be extracted to infer the long-term history of mountain uplift with numerical models. Here we focus on the southeastern (SE) Tibetan Plateau where three of the world’s largest rivers draining the Tibetan Plateau (the Yangtze, Mekong, and Salween Rivers, i.e., Three Rivers) have incised deep valleys with distinctive geomorphic signatures. We reproduce the uplift history of the SE Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region. Our model was optimized through a formal inverse analysis with a large number of forward simulations, which aims to reconcile the transient states of the present-day river profiles. The modeling results were ultimately compared to existing thermochronologic and paleoelevation datasets to help decipher between competing tectonic models that predict contrasting topographic evolutions. Our results suggest initially low elevations during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin until present day. The modeling thus does not support Paleogene formation of the SE Tibetan Plateau with a major subsequent degradation via upstream fluvial erosion. The scenario with pre-existing high-elevation plateau or plateau degradation will result in much wider river channels with knickpoints that propagated upstream much further away from the plateau margin compared to observed river profiles. The quantitative constraints on landscape evolution achieved based on drainage patterns in SE Tibet indicate a powerful tool potentially applicable to other regions to infer important implications for the evolution of Indian-Eurasian collision, Asian monsoons, and biodiversity, as well as the geodynamic forces involved in collisional orogens.

Published
2023

3. Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar

Author

Huasheng Huang, Robert J. Morley, Raymond van der Ham, Limi Mao, Alexis Licht, Guillaume Dupont-Nivet, Zaw Win, Day Wa Aung, Carina Hoorn, University of Amsterdam [Amsterdam] (UvA), Università degli Studi di Firenze = University of Florence (UniFI), University of London [London], Naturalis Biodiversity Center [Leiden], Nanjing Institute of Geology and Palaeontology (NIGPAS-CAS), Chinese Academy of Sciences [Nanjing Branch], Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), 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), University of Potsdam = Universität Potsdam, Shwe Bo University, University of Yangon, China Scholarship Council (CSC grant 201604910677), University of Amsterdam, ANR-19-ERC7-0007,DISPERSAL,Un contrôle tectonique ou climatique sur la dispersion des premiers primates ? Investigation de la dynamique des espèces invasives au cours des temps géologiques(2019), and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)

Subjects
Paleontology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Ecology, Evolution, Behavior and Systematics
Abstract

International audience; As a crossroads for plant dispersal between Laurasia and Gondwana since at least the late Eocene, the Central Myanmar Basins have yielded rich and diverse fossil pollen. Here we report Grimmipollis burmanica, a new genus and species in the soapberry family (Sapindaceae) from the upper Eocene Yaw Formation in the Central Myanmar Basins. We also investigate its similarity of pollen sculpture with other selected genera using hierarchical cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are characterized by parasyncolporate apertures with an apocolpial field at each side, distinct margines along the colpi, arcuate, tuberculate and rope-shaped mesocolpial ridges, and prominent, verrucate or fossulate apocolpia. These features distinguish this genus from other syncolporate and parasyncolporate types in the extant Sapindaceae genera, and fossil pollen genera. As most syncolporate and parasyncolporate types occur in the tribe Cupanieae, G. burmanica is likely derived from an extinct Cupanieae and thus a rainforest tree species. The hierarchical cluster analysis confirms our establishment of Grimmipollis, and reveals it is morphologically close to Meyeripollis. The sedimentary environment from which these pollen grains were retrieved suggests that G. burmanica could be a member of seasonal swamp forests.

Published
2023

4. Downstream propagation of fluvial erosion in Eastern Tibet

Author

X.P. Yuan, R. Jiao, J. Liu-Zeng, G. Dupont-Nivet, S.G. Wolf, X. Shen, China University of Geosciences [Wuhan] (CUG), University of Victoria [Canada] (UVIC), Tianjin University (TJU), 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), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), University of Bergen (UiB), National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing, China, NSFC (Grant 42272261, 42073052, 42030305), and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)

Subjects
Geophysics, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract

International audience; Fluvial erosion of small mountain belts is widely represented as a wave of upstream migration of knickpoints, starting from a stationary boundary of a high topography created by increased rock uplift rates. However, fluvial erosion remains poorly constrained when orogens expand in width with their boundaries continuously advancing towards the foreland. Here we propose a simple analytical solution for a laterally expanding orogen dominated by fluvial erosion, and apply it to the propagation of Eastern Tibet where the plateau margin is characterized by widespread low-relief surfaces incised by steep river valleys. Our analytical solution is based on the assumption that the topography of Eastern Tibet was built by high uplift rates located in a belt along the plateau margins migrating outwards during plateau growth, as well as carved by erosion of large rivers originating from the interior of the plateau. We validate our analytical solution by comparing it to numerical models and various types of data from five large rivers in Eastern Tibet (Salween, Mekong, Yangtze, Yalong, and Dadu Rivers). The results show that the models with optimized parameter values are generally consistent with the observed river-profile morphologies, exhumation magnitudes, and low-temperature thermochronometric ages. Our results show that the long-term fluvial erosion in Eastern Tibet features mainly a downstream migration of high erosion rates, which is fundamentally different from the headward erosion of most of small mountain rivers. The analytical solutions also predict a characteristic maximum plateau size set by the balance between the horizontal propagating velocity of plateau growth and the bedrock erodibility. The characteristics described by our simple analytical solution may represent a common pattern of outward growing mountains and plateaus in tectonically active regions on Earth.

Published
2023

5. Paleogeographic reconstructions using QGIS: Introducing Terra Antiqua plugin and its application to 30 and 50 Ma maps

Author

Aminov, J., Dupont-Nivet, G., Ruiz, D., Gailleton, B., University of Central Asia, Institute of Tibetan Plateau Research, Chinese Academy of Sciences [Changchun Branch] (CAS), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), 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), Institute of Geosciences, University of Potsdam, Potsdam, Germany, PIFI postdoctoral fellowship from Chinese Academy of Sciences [grant number 2019PM0039], Deutscher Akademischer Austausch Dienst (DAAD) research grant, and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)

Subjects
Paleogeography, Earth System Sciences, General Earth and Planetary Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Reconstruction, GIS, Software, Paleogene, Paleoenvironment
Abstract

International audience; Paleogeographic maps play a central integrating role across all the disciplines of the Earth System Sciences. They increasingly serve as boundary conditions for climate, earth, and life models and are widely used to convey our understanding of the Earth System's evolution. We review methods and data used for making paleogeographic reconstructions that provide a background for using Terra Antiqua, a user-friendly interface software for a broader community of users and applications. The review also clarifies the context that led to the development of this new software for paleogeographic reconstructions that combines the power of GPlates, a tectonic reconstruction software, and QGIS, a leading open-source GIS software, to make the reconstruction process easy, flexible, intuitive, and fast with a set of innovative tools. Being developed as a plugin for QGIS, Terra Antiqua makes use of the QGIS Python API, providing users with advanced geospatial data processing algorithms coupled with an intuitive graphical user interface. It has a modular structure, breaking the whole reconstruction process into small steps and providing users with flexibility in their reconstructions. Terra Antiqua comes with detailed user guidelines, manuals, and video tutorials on www.paleoenvironment.eu/terra-antiqua. The current limitations and potential developments of Terra Antiqua are discussed, including, amongst others, the estimation and mapping uncertainties, generating more realistic geomorphic features, and the integration of databases in a web application.

Published
2023

6. A proto-monsoonal climate in the late Eocene of Southeast Asia: Evidence from a sedimentary record in central Myanmar

Author

Huasheng Huang, Robert J. Morley, Alexis Licht, Guillaume Dupont-Nivet, Daniel Pérez-Pinedo, Jan Westerweel, Zaw Win, Day Wa Aung, Eko Budi Lelono, Galina N. Aleksandrova, Ramesh K. Saxena, Carina Hoorn, Institute for Biodiversity and Ecosystem Dynamics (IBED), University of London [London], Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), University of Potsdam = Universität Potsdam, 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), University of Amsterdam [Amsterdam] (UvA), Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada] (MUN), Geology Department, Shwe Bo University, Sagaing Region, Geology Department, University of Yangon, Pyay Rd, Yangon, Badan Geologi, Geological Institute of the Russian Academy of Sciences, Russian Academy of Sciences [Moscow] (RAS), Birbal Sahni Institute of Palaeosciences, China Scholarship Council (CSC grant 201604910677), University of Amsterdam, ANR-19-ERC7-0007,DISPERSAL,Un contrôle tectonique ou climatique sur la dispersion des premiers primates ? Investigation de la dynamique des espèces invasives au cours des temps géologiques(2019), European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Ecosystem and Landscape Dynamics (IBED, FNWI), and IBED (FNWI)

Subjects
Diversity, Monsoon, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Bioclimatic analysis, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Sequence biostratigraphy, General Earth and Planetary Sciences, Palynology, Southeast Asia
Abstract

International audience; The Burma Terrane has yielded some of the earliest pieces of evidence for monsoonal rainfall in the Bay of Bengal. However, Burmese ecosystems and their potential monsoonal imprint remain poorly studied. This study focuses on the late Eocene Yaw Formation (23° N) in central Myanmar, which was located near the equator (c. 5° N) during the Eocene. We quantitatively assessed the past vegetation, climate, and depositional environments with sporomorph diagrams, bioclimatic analysis, and sequence biostratigraphy. We calculated the palynological diversity and drew inferences with rarefaction analysis by comparing with four other middle to late Eocene tropical palynofloras. Palynological results highlight a high floristic diversity for the palynoflora throughout the section formed by six pollen zones characterized by different vegetation. They indicate that lowland evergreen forests and swamps dominated in the Eocene Burmese deltaic plains while terra firma areas were occupied by seasonal evergreen, seasonally dry, and deciduous forests. This vegetation pattern is typical to what is found around the Bay of Bengal today and supports a monsoon-like climate at the time of the Yaw Formation. Bioclimatic analysis further suggests that in the late Eocene, the Yaw Formation was more seasonal, drier, and cooler compared to modern-day climate at similar near-equatorial latitude. More seasonal and drier conditions can be explained by a well-marked seasonal migration of the Intertropical Convergence Zone (ITCZ), driver of proto-monsoonal rainfall. Cooler temperatures in the late Eocene of central Myanmar may be due to the lack of adequate modern analogues for the Eocene monsoonal climate, while those found at other three Eocene Asian paleobotanical sites (India and South China) may be caused by the effect of canopy evapotranspirational cooling. Our data suggest that paleoenvironmental change including two transgressive-regressive depositional sequences is controlled by global sea level change, which may be driven by climate change and tectonics. The high diversity of the Yaw Formation palynoflora, despite well-marked seasonality, is explained by its cross-roads location for plant dispersals between India and Asia.

Published
2023

7. Sporopollenin chemistry and its durability in the geological record: an integration of extant and fossil chemical data across the seed plants

Author

Phillip E. Jardine, Huajie He, Guillaume Dupont-Nivet, Amber Woutersen, William D. Gosling, Matteo Sciumbata, Wesley T. Fraser, Natasha Barbolini, Huasheng Huang, Barry H. Lomax, Giovanni Bogota-Angel, Carina Hoorn, Maxine A.M. Beer, Kustatscher, Evelyn, Jardine, Phillip E., 1Institute of Geology & Palaeontology University of Münster 48149 Münster Germany, Hoorn, Carina, 2Department of Ecosystem & Landscape Dynamics Institute for Biodiversity & Ecosystem Dynamics (IBED) University of Amsterdam 1090 GE Amsterdam The Netherlands, Beer, Maxine A.M., Barbolini, Natasha, Woutersen, Amber, Bogota‐Angel, Giovanni, Gosling, William D., Fraser, Wesley T., 5Geography, Department of Social Sciences Oxford Brookes University Oxford OX3 0BP UK, Lomax, Barry H., 6Agriculture & Environmental Science University of Nottingham Sutton Bonington Campus Leicestershire LE12 5RD UK, Huang, Huasheng, Sciumbata, Matteo, He, Huajie, 7Germplasm Bank of Wild Species Kunming Institute of Botany Chinese Academy of Sciences Kunming Yunnan China, Dupont‐Nivet, Guillaume, 8Institute of Geosciences University of Potsdam 14476 Potsdam Germany, Westfälische Wilhelms-Universität Münster = University of Münster (WWU), University of Amsterdam [Amsterdam] (UvA), Stockholm University, Universidad Distrital Francisco Jose de Caldas [Bogota], Oxford Brookes University, University of Nottingham, UK (UON), Kunming Institute of Botany [CAS] (KIB), Chinese Academy of Sciences [Beijing] (CAS), University of Potsdam = Universität Potsdam, 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), UK Research & Innovation (UKRI), NERC Natural Environment Research Council, German Research Foundation (DFG), European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Systems Ecology, University of Münster, University of Potsdam, 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), and Ecosystem and Landscape Dynamics (IBED, FNWI)

Subjects
0106 biological sciences, 010506 paleontology, Range (biology), Geologic record, medicine.disease_cause, 010603 evolutionary biology, 01 natural sciences, Nitraria, Paleontology, Fourier transform infrared (FTIR) microspectroscopy Palaeontology Palaeontology, Sporopollenin, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Pollen, medicine, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Palynology, biology, seed plants, 15. Life on land, biology.organism_classification, Diagenesis, chemotaxonomy, Taxon, sporopollenin, Fourier transform infrared (FTIR) microspectroscopy, pollen, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, 560.47, diagenesis
Abstract

Sporopollenin is a highly resistant biopolymer that forms the outer wall of pollen and spores (sporomorphs). Recent research into sporopollenin chemistry has opened up a range of new avenues for palynological research, including chemotaxonomic classification of morphologically cryptic taxa. However, there have been limited attempts to directly integrate extant and fossil sporopollenin chemical data. Of particular importance is the impact of sample processing to isolate sporopollenin from fresh sporomorphs, and the extent of chemical changes that occur once sporomorphs enter the geological record. Here, we explore these issues using Fourier transform infrared (FTIR) microspectroscopy data from extant and fossil grass, Nitraria (a steppe plant), and conifer pollen. We show a 98% classification success rate at subfamily level with extant grass pollen, demonstrating a strong taxonomic signature in isolated sporopollenin. However, we also reveal substantial chemical differences between extant and fossil sporopollenin, which can be tied to both early diagenetic changes acting on the sporomorphs and chemical derivates of sample processing. Our results demonstrate that directly integrating extant and late Quaternary chemical data should be tractable as long as comparable sample processing routines are maintained. Consistent differences between extant and deeper time sporomorphs, however, suggests that classifying fossil specimens using extant training sets will be challenging. Further work is therefore required to understand and simulate the effects of diagenetic processes on sporopollenin chemistry., Natural Environment Research Council http://dx.doi.org/10.13039/501100000270, H2020 European Research Council http://dx.doi.org/10.13039/100010663

Published
2021

8. Middle to late Miocene growth of the North Pamir

Author

Guillaume Dupont-Nivet, Niels Meijer, Lin Li, Marc Poujol, Mustafa Kaya, Jovid Aminov, Yani Najman, 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), Rochester Institute of Technology, University of Arizona, University of Potsdam = Universität Potsdam, Lancaster University, Chinese Academy of Sciences [Beijing] (CAS), MAGIC 649081, European Research Council, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), 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), and University of Potsdam

Subjects
Lithostratigraphy, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Provenance, 010504 meteorology & atmospheric sciences, Tajik Basin, Magnetostratigraphy, Geology, Late Miocene, Structural basin, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Tectonics, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Sedimentary rock, 0105 earth and related environmental sciences, Zircon, Pamir, Stable isotopes
Abstract

International audience; How and when the Pamir formed remains an open question. This study explores Pamir tectonics recorded in a sedimentary section in the eastern Tajik Basin. A prominent lithofacies change that has been recognized regionally is assigned to the middle Miocene (13.5 Ma based on preferred magnetostratigraphic correlation). Closely following this change, detrital zircon U-Pb age spectra and mudstone bulk-rock  Nd values exhibit a sediment source change from the Central to the North Pamir estimated ca. 12 Ma. At the same time, the stable oxygen and carbon isotopic values of carbonate cements show negative and positive shifts, respectively. Combined with previous studies in both the Tajik and Tarim basins, these results suggest that the North Pamir experienced a middle-late Miocene phase of deformation and surface uplift. This supports models proposing middle-late Miocene Pamir tectonism, and climate models implying that coeval Pamir orogenesis deflected Westerly moisture and affected Asian environments.

Published
2022

9. Dynamics of pedogenic carbonate growth in the tropical domain of Myanmar

Author

A. Licht, J. Kelson, S. Bergel, A. Schauer, S. V. Petersen, A. Capirala, K. W. Huntington, G. Dupont‐Nivet, Zaw Win, Day Wa Aung, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), University of Washington [Seattle], University of Michigan [Ann Arbor], University of Michigan System, 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), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-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), Geology Department, Shwe Bo University, Sagaing Region, Geology Department, University of Yangon, Pyay Rd, Yangon, University of Washington, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), 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
Geophysics, Geochemistry and Petrology, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; Pedogenic carbonate is widespread at mid latitudes where warm and dry conditions favor soil carbonate growth from spring to fall. The mechanisms and timing of pedogenic carbonate formation are more ambiguous in the tropical domain, where long periods of soil water saturation and high soil respiration enhance calcite dissolution. This paper provides stable carbon, oxygen and clumped isotope values from Quaternary and Miocene pedogenic carbonates in the tropical domain of Myanmar, in areas characterized by warm (>18°C) winters and annual rainfall up to 1700 mm. We show that carbonate growth in Myanmar is delayed to the driest and coldest months of the year by sustained monsoonal rainfall from mid spring to late fall. The range of isotopic variability in Quaternary pedogenic carbonates can be solely explained by temporal changes of carbonate growth within the dry season, from winter to early spring. We propose that high soil moisture year-round in the tropical domain narrows carbonate growth to the driest months and makes it particularly sensitive to the seasonal distribution of rainfall. This sensitivity is also enabled by high winter temperatures, allowing carbonate growth to occur outside the warmest months of the year. This high sensitivity is expected to be more prominent in the geological record during times with higher temperatures and greater expansion of the tropical realm. Clumped isotope temperatures, δ13C and δ18O values of tropical pedogenic carbonates are impacted by changes of both rainfall seasonality and surface temperatures; this sensitivity can potentially be used to track past tropical rainfall distribution.

Published
2022

10. Early Eocene magnetostratigraphy and tectonic evolution of the Xining Basin, NE Tibet

Author

Meijer, Niels, Dupont‐Nivet, Guillaume, Licht, Alexis, Roperch, Pierrick, Rohrmann, Alexander, Sun, Aijun, Lu, Shengcheng, Woutersen, Amber, Nowaczyk, Norbert, 2 Géosciences Rennes ‐ UMR CNRS 6118 Univ Rennes, CNRS Rennes France, 3 CNRS, IRD, INRAE, CEREGE Aix Marseille University Aix‐en‐Provence France, 4 Institute of Geological Sciences Freie Universität Berlin Berlin Germany, 5 Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences Lanzhou University Lanzhou China, 8 School of Urban Construction and Environment Dongguan City College Dongguan China, 9 Department of Ecosystem and Landscape Dynamics (ELD), Institute for Biodiversity and Ecosystem Dynamics (IBED) University of Amsterdam Amsterdam the Netherlands, 10 GFZ German Research Centre for Geosciences Potsdam Germany, Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Goethe-Universität Frankfurt am Main-Senckenberg – Leibniz Institution for Biodiversity and Earth System Research - Senckenberg Gesellschaft für Naturforschung, Leibniz Association-Leibniz Association, 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), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Freie Universität Berlin, Lanzhou University, Dongguan City College, University of Amsterdam [Amsterdam] (UvA), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Hessisches Ministerium fur Wissenschaft und Kunst, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), 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), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Rennes 2 (UR2), and Université de Rennes (UNIV-RENNES)-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
ddc:551, northeast Tibet, geochronology, paleomagnetism, stratigraphy, Geology, Eocene, palaeomagnetism, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDE]Environmental Sciences, 500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::550 Geowissenschaften, Xining Basin
Abstract

The Cenozoic strata of the Xining Basin, NE Tibet, have provided crucial records for understanding the tectonic and palaeo‐environmental evolution of the region. Yet, the age of the lower part of the sedimentary stratigraphy and, consequently, the early tectonic evolution of the basin remain debated. Here, we present the litho‐ and magnetostratigraphy of various early Eocene sections throughout the Xining Basin independently constrained by the U–Pb radiometric age of a carbonate bed. Our study extends the dated stratigraphy down to 53.0 Ma (C24n.1r) and reveals highly variable accumulation rates during the early Eocene ranging from 0.5 to 8 cm/ka. This is in stark contrast to the low but stable accumulation rates (2–3 cm/ka) observed throughout the overlying Palaeogene and Neogene strata. Such a pattern of basin infill is not characteristic of flexural subsidence as previously proposed, but rather supports an extensional origin of the Xining Basin with multiple depocentres, which subsequently coalesced into a more stable and slowly subsiding basin. Whether this extension was related to the far‐field effects of the subducting Pacific Plate or the India–Asia collision remains to be confirmed by future studies., European Research Council http://dx.doi.org/10.13039/501100000781, Hessisches Ministerium für Wissenschaft und Kunst http://dx.doi.org/10.13039/501100003495

Published
2022

11. Global warming-induced Asian hydrological climate transition across the Miocene–Pliocene boundary

Author

Zhangdong Jin, Zhisheng An, Andrew P. Roberts, Jean-Baptiste Ladant, Zhonghui Liu, Qiang Sun, Christopher J. Poulsen, Peng Zhang, Xinxia Li, Qingsong Liu, Xianzhe Peng, Guoxiong Wu, Mark J. Dekkers, Xiaodong Liu, Xiaoke Qiang, Alexis Licht, Ran Zhang, Eelco J. Rohling, Guillaume Dupont-Nivet, John C. H. Chiang, Yong Xu, Feng Wu, Ann Holbourn, Chao Ma, Weijian Zhou, Wolfgang Kuhnt, Xinzhou Li, Hong Ao, Chinese Academy of Sciences [Xi’an], Australian National University (ANU), University of Southampton, Chinese Academy of Sciences [Beijing] (CAS), Christian-Albrechts University of Kiel, University of Michigan [Ann Arbor], University of Michigan System, 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), Utrecht University [Utrecht], Southern University of Science and Technology [Shenzhen] (SUSTech), The University of Hong Kong (HKU), China Geological Survey, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Xi'an University of Science and Technology, University of California [Berkeley], University of California, Chengdu University of Technology (CDUT), China University of Geosciences [Wuhan] (CUG), Nanjing University (NJU), European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Department of Earth and Environmental Sciences [Ann Arbor], University of Michigan System-University of Michigan System, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut 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), 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), University of Applied Sciences Potsdam (FHP), Institute of Earth Environment [Xi’an], Qingdao National Laboratory for Marine Science and Technology, Paleomagnetic Laboratory Fort Hoofddijk [Utrecht], Universiteit Utrecht, Southern University of Science and Technology (SUSTech), University of Washington [Seattle], University of California [Berkeley] (UC Berkeley), University of California (UC), This study was supported financially by the Chinese Academy of Sciences (CAS) Strategic Priority Research Program (XDB 40000000), the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (2019QZKK0707), the Chinese Academy of Sciences Key Research Program of Frontier Sciences (QYZDB-SSW-DQC021), the National Natural Science Foundation of China, the Ministry of Science and Technology of China, Australian Research Council (ARC) Australian Laureate Fellowship grant FL120100050 to E.J.R., ARC grant DP120103952 to A.P.R., ERC consolidator grant MAGIC 649081 to G.D.-N., and Heising-Simons Foundation Grant #2016-05 to C.J.P., and Paleomagnetism

Subjects
010504 meteorology & atmospheric sciences, Chemistry(all), Science, Population, General Physics and Astronomy, Late Miocene, Physics and Astronomy(all), 010502 geochemistry & geophysics, Monsoon, Palaeoclimate, 01 natural sciences, Biochemistry, General Biochemistry, Genetics and Molecular Biology, Article, Climate change, East Asia, education, 0105 earth and related environmental sciences, education.field_of_study, Multidisciplinary, Biochemistry, Genetics and Molecular Biology(all), Global warming, General Chemistry, 15. Life on land, 13. Climate action, Aridification, Climatology, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Aeolian processes, Climate model, Geology, Genetics and Molecular Biology(all)
Abstract

Across the Miocene–Pliocene boundary (MPB; 5.3 million years ago, Ma), late Miocene cooling gave way to the early-to-middle Pliocene Warm Period. This transition, across which atmospheric CO2 concentrations increased to levels similar to present, holds potential for deciphering regional climate responses in Asia—currently home to more than half of the world’s population— to global climate change. Here we find that CO2-induced MPB warming both increased summer monsoon moisture transport over East Asia, and enhanced aridification over large parts of Central Asia by increasing evaporation, based on integration of our ~1–2-thousand-year (kyr) resolution summer monsoon records from the Chinese Loess Plateau aeolian red clay with existing terrestrial records, land-sea correlations, and climate model simulations. Our results offer palaeoclimate-based support for ‘wet-gets-wetter and dry-gets-drier’ projections of future regional hydroclimate responses to sustained anthropogenic forcing. Moreover, our high-resolution monsoon records reveal a dynamic response to eccentricity modulation of solar insolation, with predominant 405-kyr and ~100-kyr periodicities between 8.1 and 3.4 Ma., Global warming drove ‘wet gets wetter and dry gets drier’ climate shifts in Asia ~5.3 million years ago with monsoon pacing by ~400,000 and ~ 100,000 year cycles. This could be a template for future Asian climate response to anthropogenic warming.

Published
2021

12. Towards interactive global paleogeographic maps, new reconstructions at 60, 40 and 20 Ma

Author

Poblete, F., Dupont-Nivet, G., Licht, A., van Hinsbergen, D. J.J., Roperch, P., Mihalynuk, M. G., Johnston, S. T., Guillocheau, F., Baby, G., Fluteau, F., Robin, C., van der Linden, T. J.M., Ruiz, D., Baatsen, M. L.J., Mantle dynamics & theoretical geophysics, Marine and Atmospheric Research, Sub Dynamics Meteorology, Universidad de Chile = University of Chile [Santiago] (UCHILE), 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), University of Potsdam = Universität Potsdam, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Utrecht University [Utrecht], British Columbia Geological Survey, University of Alberta, 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), European Research Council, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Universidad de Chile, 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), Universität Potsdam, Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Mantle dynamics & theoretical geophysics, Marine and Atmospheric Research, and Sub Dynamics Meteorology

Subjects
Paleomagnetism, 010504 meteorology & atmospheric sciences, Earth and Planetary Sciences(all), Climate change, Tibetan-Himalayan orogen, 010502 geochemistry & geophysics, 01 natural sciences, Eocene-Oligocene transition, Paleontology, Oceanic crust, Paleoclimatology, paleoclimate, Sea level, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Cenozoic, Paleoelevation, 15. Life on land, Collision zone, Paleogeographic maps, Earth system science, Plate tectonics, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, General Earth and Planetary Sciences, Geology
Abstract

International audience; Paleogeographic maps are essential tools for understanding Earth system dynamics. They provide boundary conditions for climate and geodynamic modelling, for analysing surface processes and biotic interactions. However, the temporal and spatial distribution of key features such as seaways and mountain belts that govern climate changes and biotic interchange differ between various paleogeographies that require regular updates with new data and models. We developed a reproducible and systematic approach to paleogeographic reconstruction and provide a set of worldwide Cenozoic paleogeographic maps at 60, 40 and 20 Ma. We followed a six-stage methodology that integrates an extensive review of geological data into a coherent plate tectonic model using the open source software GPlates. (1) We generated a global plate kinematic model, and reconstructed intensely-deformed plate boundaries using a review of structural, paleomagnetic and other geologic data in six key regions: the Andes, the North American Cordillera, the Scotia Arc, Africa, the Mediterranean region and the Tibetan-Himalayan collision zone. (2) We modified previously published paleobathymetry in several regions where continental and oceanic crust overlap due to differences in the plate models. (3) We then defined paleoshorelines using updated fossil and geologic databases to locate the terrestrial to marine transition. (4) We applied isostatic compensation in polar regions and global eustatic sea level adjustments. (5) Paleoelevations were estimated using a broad range of data including thermochronology and stable isotopes, combined with paleobotanical (mostly pollen and leaf physiognomy), structural and geomorphological data. We address ongoing controversies on the mechanisms and chronology of India-Asia collision by providing alternate reconstructions for each time slice. We finally discuss the implications of our reconstructions on the Cenozoic evolution of continental weatherability and review methodological limitations and potential improvements. Future addition of new data, tools and reconstructions can be accommodated through a dedicated interactive website tool (https://map.paleoenvironment.eu/) that enables users to interactively upload and download data and compare with other models, and generate their own plots. Our aim is to regularly update the models presented here with new data as they become available.

Published
2021

13. Age and driving mechanisms of the Eocene-Oligocene Transition from astronomical tuning of a lacustrine record (Rennes Basin, France)

Author

Slah Boulila, Guillaume Dupont-Nivet, Bruno Galbrun, Hugues Bauer, Jean-Jacques Châteauneuf, Sorbonne Université (SU), Géosciences Rennes (GR), 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), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Chercheur indépendant, Marie-Curie (CIG HIRESDAT), ANR-19-CE31-0002,AstroMeso,Solution astronomique pour le Mésozoïque(2019), European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), 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), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), 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 de Lille-Sorbonne Université (SU)-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), 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), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Rennes 2 (UR2), and Université de Rennes (UNIV-RENNES)-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
lacustrine record, 13. Climate action, Eocene-Oligocene Transition, lacustrine record, astronomical tuning, Rennes basin (France), [SDU]Sciences of the Universe [physics], Rennes basin (France), [SDE]Environmental Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 15. Life on land, astronomical tuning, Eocene-Oligocene Transition
Abstract

The Eocene-Oligocene Transition (EOT) marks the onset of the Antarctic glaciation and the switch from greenhouse to icehouse climates. However, the driving mechanisms and the precise timing of the EOT remain controversial mostly due to the lack of well-dated stratigraphic records, especially in continental environments. Here we present a cyclo-magnetostratigraphic and sedimentological study of a ∼7.6 Myr-long lacustrine record spanning the late Eocene to the earliest Oligocene, from a drill-core in the Rennes Basin (France). Time-series analysis of natural gamma-ray (NGR) log data shows evidence of Milankovitch cycle bands. In particular, the 405 kyr stable eccentricity is expressed with strong amplitudes. Astronomical calibration to this 405 kyr periodicity yields duration estimates of Chrons C12r through C16n.1n, providing additional constraints on the middle–early Eocene timescale. Correlations between the orbital eccentricity curve and the 405 kyr tuned NGR time series and assumptions on their phase relationships, enable to test previously proposed ages for the EO boundary, indicating that 33.71 and 34.10 Ma are the most likely. Additionally, the 405 kyr tuning calibrates the most pronounced NGR cyclicity to a period of ∼1 Myr matching the g1-g5 eccentricity term. Such cyclicity has been recorded in other continental records, pointing to its significant expression in continental depositional environments. The record of g1-g5 and sometimes g2-g5 eccentricity terms in previously acquired sedimentary facies proxies in CDB1 core led us to hypothesize that the paleolake level may have behaved as a lowpass filter for orbital forcing. Two prominent changes in the sedimentary facies were detected across the EOT, which are temporally equivalent to the two main climatic steps, EOT-1 and Oi-1. Combined with previously acquired geochemical (δ15Norg, TOC), mineralogical (Quartz, clays) and pollen assemblage proxies from CDB1, we suggest that these two facies changes reflect the two major Antarctic cooling/glacial phases via the hydrological cycle, as significant shifts to drier and cooler climate conditions, thus supporting the stepwise nature of the EOT. Remarkably, a strongly dominant obliquity expressed in the latest Eocene corresponds in time to the interval from the EOT precursor glacial event till the EOT-1. We interpret the obliquity dominance as reflecting preconditioning phases for the onset of the major Antarctic glaciation, either from its direct impact on the formation/(in)stability of the incipient Antactic Ice Sheet (AIS), or through its modulation of the North Atlantic Deep Water production given the North Atlantic coastal location of the CDB1 site.

Published
2021

14. At a crossroads: The late Eocene flora of central Myanmar owes its composition to plate collision and tropical climate

Author

Huasheng Huang, Daniel Pérez-Pinedo, Alexis Licht, Phillip E. Jardine, Annemarie Philip, Carina Hoorn, Robert J. Morley, Zaw Win, Day Wa Aung, Guillaume Dupont-Nivet, University of Amsterdam [Amsterdam] (UvA), University of London [London], Géosciences Rennes (GR), 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), Universität Potsdam, University of Shwebo, University of Yangon, 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 National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), University of Münster, China Scholarship Council (CSC grant 201604910677), University of Amsterdam, German Research Foundation (DFG grant 443701866), European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Ecosystem and Landscape Dynamics (IBED, FNWI), IBED (FNWI), 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), University of Potsdam = Universität Potsdam, 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), and Westfälische Wilhelms-Universität Münster = University of Münster (WWU)

Subjects
0106 biological sciences, 010506 paleontology, Monsoon, Biogeography, 010603 evolutionary biology, 01 natural sciences, Vegetation Highlights, Paleontology, Tropical climate, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Terrane, Palynology, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Sapotaceae, Gondwana, Vegetation, 15. Life on land, Geography, Laurasia, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Global cooling
Abstract

International audience; Myanmar was shaped by the India–Asia collision, fusion of the Burma Terrane (BT) with Asia, and mountain building. Throughout this process new elevational gradients and habitats were formed, which affected the regional climate, but also forged new dispersal routes into Asia and India. In spite of its importance, the vegetation history of Myanmar is poorly known, and this hinders our understanding on the origins and evolution of SE Asian biodiversity. In this study we reconstruct the late Eocene flora in central Myanmar, based on samples from a sedimentary succession in Kalewa, and extend on the Sapotaceae fossil record with additional early Eocene–early Oligocene samples. We then study the morphology, botanical affinity, source ecology and biogeography of selected sporomorphs, and assess the Gondwanan and Laurasian components. Our results show that the Eocene palynoflora is representative for evergreen forests, typical in a seasonal wet climate, with dryer vegetation away from the area of sedimentation. The abundance of Sapotaceae further suggests that this family became an important component of the SE Asian flora shortly after the India–Asia collision. We conclude that the late Eocene geographic position and Gondwanan origin of Myanmar facilitated floristic exchange between the Indian Plate, BT, mainland and SE Asia, making the BT a crossroads for plant dispersals between Gondwana and Laurasia. The shift from late Eocene seasonal evergreen to present-day moist deciduous forests was likely due to the northward drift of Myanmar, the subsequent two-stage uplift of the Indo-Burman Ranges and posterior Neogene global cooling and drying.

Published
2021

15. The origin of Asian monsoons: a modelling perspective

Author

Pierre Sepulchre, Fernando Poblete, Guillaume Dupont-Nivet, Jean-Baptiste Ladant, Alexis Licht, Delphine Tardif, Frédéric Fluteau, Guillaume Le Hir, Yannick Donnadieu, 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), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Earth and Environmental Sciences [Ann Arbor], University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Modélisation du climat (CLIM), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], Universidad de Chile = University of Chile [Santiago] (UCHILE), 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), INSU-CNRS TelluS-Syster Paleomonsoon, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Rennes 1 (UR1), and 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)

Subjects
010504 meteorology & atmospheric sciences, Atmospheric circulation, Stratigraphy, lcsh:Environmental protection, Climate change, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, lcsh:Environmental pollution, East Asian Monsoon, lcsh:TD169-171.8, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Intertropical Convergence Zone, Paleontology, 15. Life on land, Tethys Ocean, Arid, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, lcsh:TD172-193.5, Cenozoic, Geology
Abstract

The Cenozoic inception and development of the Asian monsoons remain unclear and have generated much debate, as several hypotheses regarding circulation patterns at work in Asia during the Eocene have been proposed in the few last decades. These include (a) the existence of modern-like monsoons since the early Eocene; (b) that of a weak South Asian monsoon (SAM) and little to no East Asian monsoon (EAM); or (c) a prevalence of the Intertropical Convergence Zone (ITCZ) migrations, also referred to as Indonesian–Australian monsoon (I-AM). As SAM and EAM are supposed to have been triggered or enhanced primarily by Asian palaeogeographic changes, their possible inception in the very dynamic Eocene palaeogeographic context remains an open question, both in the modelling and field-based communities. We investigate here Eocene Asian climate conditions using the IPSL-CM5A2 (Sepulchre et al., 2019) earth system model and revised palaeogeographies. Our Eocene climate simulation yields atmospheric circulation patterns in Asia substantially different from modern conditions. A large high-pressure area is simulated over the Tethys ocean, which generates intense low tropospheric winds blowing southward along the western flank of the proto-Himalayan–Tibetan plateau (HTP) system. This low-level wind system blocks, to latitudes lower than 10∘ N, the migration of humid and warm air masses coming from the Indian Ocean. This strongly contrasts with the modern SAM, during which equatorial air masses reach a latitude of 20–25∘ N over India and southeastern China. Another specific feature of our Eocene simulation is the widespread subsidence taking place over northern India in the midtroposphere (around 5000 m), preventing deep convective updraught that would transport water vapour up to the condensation level. Both processes lead to the onset of a broad arid region located over northern India and over the HTP. More humid regions of high seasonality in precipitation encircle this arid area, due to the prevalence of the Intertropical Convergence Zone (ITCZ) migrations (or Indonesian–Australian monsoon, I-AM) rather than monsoons. Although the existence of this central arid region may partly result from the specifics of our simulation (model dependence and palaeogeographic uncertainties) and has yet to be confirmed by proxy records, most of the observational evidence for Eocene monsoons are located in the highly seasonal transition zone between the arid area and the more humid surroundings. We thus suggest that a zonal arid climate prevailed over Asia before the initiation of monsoons that most likely occurred following Eocene palaeogeographic changes. Our results also show that precipitation seasonality should be used with caution to infer the presence of a monsoonal circulation and that the collection of new data in this arid area is of paramount importance to allow the debate to move forward.

Published
2020

16. Magnetic response to pedogenesis in aerobic soils of different weathering degree

Author

Wei Wang, Guillaume Dupont-Nivet, Chenglong Deng, Caicai Liu, State Key Laboratory of Earthquake Dynamics, China Earthquake Administration (CEA), Géosciences Rennes (GR), 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), University of Potsdam, Key Laboratory of Orogenic Belts and Crustal Evolution, Peking University [Beijing], Institute of Cultural Heritage, State Key Laboratory of Lithospheric Evolution (SKL), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), National Key R&D Program of China 2017YFC1500104, Second Tibetan Plateau Scientific Expedition and Research (STEP) grant 2019QZKK0704, National Natural Science Foundation of China (NSFC) 41622204, 41761144071, 41474053, 41690112, 41621004, Marie-Curie CIG Hiresdat grant, Alexander von Humboldt Foundation, European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015), 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), and University of Potsdam = Universität Potsdam

Subjects
010506 paleontology, Environmental magnetism, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Paleontology, Maghemite, Mineralogy, Weathering, 15. Life on land, Hematite, engineering.material, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Pedogenesis, 13. Climate action, Remanence, visual_art, visual_art.visual_art_medium, engineering, Sedimentary rock, Red soil, Ecology, Evolution, Behavior and Systematics, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

International audience; Magnetic parameters are widely used to indicate paleoclimatic and paleoenvironmental conditions in sedimentary records. However, the relations between magnetic parameters and paleoclimate conditions are very different depending on the weathering degree. This study explores various multidisciplinary parameters across an intensely weathered red soil section in the Bose Basin (the Damei sequence with layers of different weathering intensity) of subtropical southern China to understand the magnetic mineral response to pedogenesis in aerobic soils. We find that the only commonly used environmental magnetic parameter that correlates well with geochemical indices of weathering intensity, is the S-ratio (a measure of the relative amounts of high-coercivity remanence to low-coercivity remanence). HIRM (the absolute amount of high-coercivity remanence) and -IRM-0.3T (the absolute amount of low-coercivity remanence) are the main variable in S-ratio. Mineral magnetic analyses indicate that the main carriers of HIRM and -IRM-0.3T in the Damei red soils are respectively hematite and maghemite. Negative correlations between the S-ratio, the IRM-0.3T and the weathering intensity, and a positive correlation between the HIRM and the weathering intensity relates to the transformation of pedogenic maghemite into hematite which is favored in such a case of intense weathering. It seems that environmental interpretations from magnetic parameters are better constrained if the weathering stage can be first determined using the relation between concentration of hematite and ferrimagnetic minerals. A new magnetic weathering index is proposed for intensely weathered red soils based on the slope of the linear correlation between HIRM and -IRM-0.3T. These results open applications for assessing weathering and pedoclimate proxies using environmental magnetism.

Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results