Geochemistry of sediments from Barkol Lake in the westerly influenced northeast Xinjiang: Implications for catchment weathering intensity during the Holocene

Abstract

Though considerable studies concerning past climate changes in the Xinjiang, northwest China, have been performed, Holocene climate changes of this area are still poorly documented and understood. In this study, we emphasize the potential of geochemical elements in sediments for indicating the chemical weathering intensity (CWI) of Bakol Lake catchment during the Holocene. The results indicate that the CWI represented by ratios of (Ca+Mg+Na+K)/Al, Ca/Mg, Ca/Al, Mg/Al, Si/Al, Mn/Al and Ca/Al, has the potential to reflect past climatic conditions. Three weakened CWI periods, i.e., from 9400–7600cal a BP, from 6000–5000cal a BP and since 2000cal a BP afterwards, and two strengthened CWI periods, i.e., from 7600–6000cal a BP and from 5000–4000cal a BP, are revealed. In combination of multi-proxy records including carbonate δ18O and δ13C, total carbonate content, as well as total organic carbon, we find the thermal conditions possibly played an important role in the CWI of lake catchment, with a warmer climate favoring stronger CWI and vice versa. In contrast, the moisture conditions appear less influence on the CWI. This new result is expected to be helpful for strengthening our understanding of the spatial and temporal patterns of Holocene climate changes in the westerly influenced region.