ANR RECA project

Laterites 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.

The RECA project is made of team of 10 international groups working on reconstructing the influence of climate change on laterite formation. The main objectives consists of dating different generations of secondary minerals from tropical soils (clays: kaolinite, and iron oxides and oxyhydroxides) by two complementary methods and linking the major weathering phases that cause these soils formation to major past climate changes. The mineralogical and geochemical approach developed in this project allows to reconstruct paleo-environmental conditions and quantify the element fluxes that generated these lateritic profiles. All the results will permit to build a global model of the evolution of tropical soils, and to predict their evolution in the face of major climate changes.

The project is concentrate on the geodynamically stable Guyana craton (Central Amazonia, North Brasil, Suriname, French Guyana), where laterites formed through the whole Cenozoic and can be associated with major geomorphological units. In addition, a second study site is located in Malawi.

Contact:  Cécile Gautheron: GEOPS, Université Paris sud; 91405 Orsay, France

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