杭州湘湖剖面全新世沉积物的地球化学记录及其地质意义

对杭州湘湖剖面高密度连续采集的样品,分析了Fe2O3、FeO、TiO2、C2CO3、Al2O3及Fe2O3／FeO比值的高分辨记录,发现它们对全新世的重要地层界面都有较清晰的反映,同时揭示了不同沉积环境下地球化学背景值存在显著的差异。运用Fe^2 ／Fe^2 与年平均温度的关系式推算了各样品点的古温度值,并结合多种地球化学指标、^14C测年结果以及岩性岩相组合特征,将湘湖地区全新世早、中期(10-3ka B．P．)初步划分为4个气候发展阶段,并指出7.5～5．1 ka B．P之间为本区的全新世气候适宜期。

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

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.