Chemical weathering since the little ice age recorded in lake sediments: Ahigh-resolution proxy of past climate

Because of the different geochemical behaviour of rubidium and strontium in earth surface processes, variations of the Rb/Sr ratios in lake sediments were used as a geochemical proxy of chemical weathering and past climate in a single watershed. Low magnetic susceptibility, low CaCO3, low Sr concent ration and, hence, high Rb/Sr ratio in the lake sediments indicate weak che mical weathering under a cold but wet climate during the Little Ice Age (LI A) in the closed Daihai Lake watershed. The concordant change in both Sr an d CaCO3 concentrations with delta O-18 values in the Dunde ice core suggest s that weak chemical weathering during the wet LIA was controlled by air te mperature. After the LIA, however, precipitation played a dominant role in chemical weathering. Copyright (C) 2001 John Wiley & Sons, Ltd.