南黄海B10岩心的地球化学特征及其对古环境和古气候的反映

Geochemical changes in Core B10 in the southern Huanghai Sea and implications for variations in paleoenvironment and paleoclimate

通过对南黄海中部B10岩心的碳酸钙、常量元素和微量元素分析发现,岩心的地球化学特征基本反映了该海区晚第四纪气候变化、海面波动以及沉积物供应的变化.在玉木亚间冰期(末次冰期亚间冰期)高海面时期,黄河可能直接注入南黄海,在南黄海中部发育水下三角洲沉积.晚玉木冰期(末次冰期盛冰期),南黄海出露成陆,局部发育陆相泥炭层.冰后期(全新世)海侵到达现今80 m等深线附近的时间大约在距今13 ka。在距今11.0～10.3 ka出现新仙女木事件.全新世中晚期海面进一步上升,沉积物粒度较细,化学风化作用加强.岩心50～0 cm段沉积物中的碳酸钙、氧化钙、锶、氧化镁含量及Sr/Ba比值低,而铜等微量元素含量增加,这可能与公元1855年黄河北迁后进入南黄海中部的黄河物质减少有关.

Variations in elemental concentrations and ratios in Core B10 taken from the southern Huanghai Sea indicate climatic oscillations, sea level fluctuations and sediment supply changes in Late Quaternary in the region. During the low sea-level period of subinterglaciation of Last Glaciation (Wurm subinterglaciation), the Huanghe River was possibly discharged directly into the southern Huanghai Sea, and the submarine delta related sediments was found in the center of the sea. During the last glacial maximum, terrestrial facies peat appeared in the center of the southern Huanghai Sea. The postglacial transgression arrived at the modern isobaths of 80 m possibly in 13 ka B. P. and then a short standstill of sea level related to the Younger Dryas event appeared. During the middle and late stages of Holocene, sea level continued to rise, and relatively fine sediments with increasing chemical weathering deposited. Decrease of concentrations of CaCQ3, CaO, Sr and MgO, Sr/Ba ratios but increase of concentrations of minor elements such as Cu in the section of 50 -0 cm are probably due to the decrease in sediment supply from the Huanghe River in the southern Huanghai Sea because the Huanghe River has transferred north and discharged into the Bohai Sea since 1855 D. C.