Geochemical records of Holocene sediments in the Xianghu section, Hangzhou, and their geological significance

Abstract：High-density consecutive sampling was undertaken from the Xianghu section, Hangzhou. For these samples the authors analyzed high-resolution records of Fe2O3, FeO, TiO2, CaCO3, Al2O3 and Fe2O3/FeO and found that they are very sensitive to some important Holocene stratigraphic boundaries and revealed that there are appreciable differences in geochemical background values in various sedimentary environments. The authors calculated paleotemperatures at different sampling sites by using the relation between Fe3+/Fe2+ and average annual temperature. On that basis, combined with various geochemical indices, 14C dating results and association characteristics of lithology and lithofacies, the early-mid Holocene (10-3 ka B.P.) in the Xianghu area is divided into four climatic evolution stages, and it is indicated that the stage of 7.5-5.1 ka BP is the Holocene “hypsithermal” in this area.