The provenance of sediments in the Gulf of Lions, western Mediterranean Sea

Abstract : In this study, we undertook a reconnaissance study of sediments provenance in the Gulf of Lions focusing over the last 16 ka. We used geochemical and isotopic tracers to determine the source of sediments and give insight into the weathering conditions prevailing. Sediments samples were selected both onshore and offshore from the western, eastern, and central part of the Gulf of Lions. We analyzed bulk sediments, coarse and fine silt, and clay fractions. Elemental and Nd isotope compositions appeared to differ from one grain size fraction to another one. These are interpreted in terms of zircon addition in the coarse silt fraction for the elemental concentrations and variable sources influences for the Nd isotope compositions. Our results indicate that sediments in the Gulf of Lions mainly originated from the Rhône River watershed although a contribution of Saharan dust is seen in one sample. Influence of Pyrenean small rivers is minor in these samples. Some Sr isotope compositions shifts are interpreted as reflecting variable amounts of chemical weathering that are consistent with published paleoclimatic reconstructions.