
Universite Paris Sud Geosciences Paris Sud
Universite Paris Sud Geosciences Paris Sud
1 Projects, page 1 of 1
assignment_turned_in ProjectFrom 2017Partners:Earth Surface Process Modelling, Exploration production / TOTAL, Laboratório de Geomorfologia, Pedologia e Geografia Física, Centre National de la Recherche Scientifique (CNRS) - Délégation Régionale Provence et Corse - Centre Européen de Recherche et dEnseignement des Géosciences de lEnvironnement, BRGM +8 partnersEarth Surface Process Modelling,Exploration production / TOTAL,Laboratório de Geomorfologia, Pedologia e Geografia Física,Centre National de la Recherche Scientifique (CNRS) - Délégation Régionale Provence et Corse - Centre Européen de Recherche et dEnseignement des Géosciences de lEnvironnement,BRGM,Centre National de la Recherche Scientifique (CNRS) - Délégation Régionale Provence et Corse - Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement,Institut de Physique Nucléaire dOrsay,Institut de physique du globe de Paris,Instituto de Geociências, Brazilia University,Bureau de recherches géologiques et minières,Institut de Physique Nucléaire d'Orsay,Universite Paris Sud Geosciences Paris Sud,Institut de Minéralogie, de Physique des Matériaux et de CosmochimieFunder: French National Research Agency (ANR) Project Code: ANR-17-CE01-0012Funder Contribution: 588,205 EURLaterites are deep weathering covers of the critical zone that occupy 80% of the total soil-mantle volume of the Earth’s landscape and significantly participate to the global geochemical budget of weathering and erosion, and greenhouse gas consumption. Despite their factual importance on Earth surface, the timing of their formation and evolution in response to climatic and geodynamic forcing are still obscure. RECA project will address both the topics of "Functioning and evolution of climate, oceans and major cycles" and "Continental Surfaces: critical zone and biosphere" from ANR Axis 1 – Challenge 1., by reconstructing the influence of climate change laterites formation. The originality of the RECA project is to combine chronometric, weathering and climatic proxies developed in the recent years in order to build a comprehensive and predictive scenario of laterite formation and evolution. We will concentrate our effort on geodynamically stable Guyana Shield and Central Amazonia regions, where laterites formed through the whole Cenozoic and can be associated with major geomorphological units. This ambitious multidisciplinary project proposes, for the first time, to perform absolute dating of lateritic duricrusts associated to five episodes of planation in the South American subcontinent. We will date mineralogically well-identified populations of iron oxides and oxyhydroxides (hematite, goethite) and clays (kaolinites) by using (U-Th)/He, (U-Th)/Ne and electron paramagnetic resonance spectroscopy, respectively. These recent methods are appropriates because they can be applied to the most common secondary minerals found in laterites and span geological time scales. The inherent complexity of weathering materials, which may contain different populations of a same secondary mineral related to distinct stages of lateritization will be taken into account. The timing of duricrust formation will then be related to paleoclimatic conditions (temperature, rainfall) derived from a combination of geochemical or mineralogical indices and proxies: (i) at global scale, through, e.g., the known continental drainage curves; (ii) at a more regional scale through the intensity of weathering, the ratio hematite/goethite or O and H isotope systems of kaolinite and iron oxides and oxyhydroxides. A second task will associate non-conventional Li, Si and Fe isotopic methods that will help to decipher the evolution of weathering processes linked to the various stages of laterite formation. Coupling weathering budget and the ages of weathering profiles will yield average weathering and erosion rates, allowing comparison with other weathering environments or paleo-environments at the Earth surface. To tackle this ambitious task, the RECA project gathers an international consortium made of skilled researchers in the identification of lateritic soils, dating methods, environmental mineralogy; "traditional" and "non-traditional" stable isotope geochemistry, and modeling approaches of the formation of weathering profiles. The synergy of the identified teams offers the highest level of guarantee to lift off the identified scientific and technical barriers, giving access to yet hidden information on soil formation as a response to climate change through geological times.
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