Erosion-climate interactions: Isotopic constraints from the sedimentary record – ECLIP-SED

Chemical weathering plays an important role in sequestering atmospheric CO2, but its potential influence on global climate over geological time remains debated. To some extent, this uncertainty arises from the difficulty in separating the respective contribution of igneous/metamorphic and sedimentary rocks to total weathering rates during mountain erosion; two types of rocks having different impact on the long-term carbon cycle. Here, we propose a novel approach for identifying the origin of weathered rocks on continents and its evolution through time, based on the combined analysis of iron oxide and detrital silicate fractions in the sediment record. After a first phase of proxy development (Nd, Hf, Fe, Si & Li isotopes), using a collection of modern river sediment samples, our new approach will be used to reconstruct, for the first time, the weathering history of the Amazon Basin for the last 30 Ma and its relationships to the Andean uplift and global climate.