Séminaire ISTerre

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Altération supergène et émergence de frontières biogéographiques majeures en Amazonie

jeudi 26 novembre 2020 - 11h00

Cécile Gautheron - GEOPS
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In Central Amazonia, the modern landscape is shaped by the Andean influence and the long-term dynamics of the river systems associated with climate change. Major Amazonian rivers constitute geographical boundaries for the distribution of many species suggesting large drainage systems represent barriers for the dispersion of terrestrial species. However, crucial information on paleogeography is missing to investigate the different biogeographic boundaries during the late Cenozoic that control biotic diversification. To access this information, we can used supergene iron products, which record the weathering history of Amazon lowlands. During this presentation, I will show how (U-Th)/He geochronological and mineralogical investigation of the iron products permit to highlight mains phases of weathering but also major change in the climatic condition with more humid environment that should have increase the paleo river extension. We can connect the change in weathering with the emergence of a major biogeographic boundary in concordance with change in the biotic diversity.

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Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères