WEATHERING CONDITIONS IN LAKE BAIKAL WATERSHED DURING INTERGLACIALS : THE LACUSTRINE CLAY RECORD

摘要

The clay mineralogical record of a piston core recovered on an elevated plateau in the northern basin of Lake Baikal has been investigated for both the Holocene and the Eemian s.s. (i.e., Kazantsevo in Siberian stratigraphy) interglacials. Clay mineralogical signature is determined by X-ray diffraction on oriented aggregates. Results are reported along a paleomagnetic-derived time scale. The sampling at a centimeter resolution allows for a centennial order reconstruction. Our aim is to test the limits of classicaly used clay proxies (e.g., smectite abundance, smectite/illite S/I ratio) as climate reconstructions. Assuming all clays are detrital, the evolution of clay assemblages keep a fingerprint of the weathering conditions within the watershed, further related to the climate regime. Clay data are compared with diatom and pollen profiles, pollen-based quantitative reconstructions and with regional climate reconstructions.