鄂霍次克海南部OS03-1岩心MIS6期以来的沉积记录及其古环境意义

通过对取自鄂霍次克海南部的柱状岩心OS03-1的古海洋学研究,包括浮游有孔虫壳体AMS14C测年、底栖有孔虫壳体δ18O分析、蛋白石含量测定、有机碳含量测定、浮游有孔虫组合、冰筏碎屑含量变化、沉积物粒度分析等内容,建立鄂霍次克海OS03-1岩心年代地层学框架,分析该海区古表层海水温度、古生产力变化,并研究其古环境意义。结果表明,Neogloboquadrina pachyderma(sin.)百分含量变化曲线与Globigerina bulloides百分含量变化曲线呈很好的负相关性,与氧同位素曲线对比显示,两者均可作为该海区古温度替代性指标;浮游有孔虫绝对丰度、蛋白石含量、有机碳含量变化显示,研究区古生产力水平整体表现为间冰期较高、冰期较低;冰筏碎屑和沉积物粒度特征指示,鄂霍次克海南部间冰期陆源粗颗粒百分含量较冰期高。

Sedimentary Record in Core OS03-1 from the Southern Okhotsk Sea since the Last Interglacial and the Paleoenvironmental Significance

Core OS03-1 was retrieved from the southern Okhotsk Sea(150°00′36″E,49°29′51″N;975-meter water depth).The core consists of 3.81 m of silty clay and 96 samples were taken.Based on the analysis of AMS 14C ages of planktonic foraminifera,oxygen isotopes of benthic foraminifera,opal content,organic carbon content,planktonic foraminifera assemblage,ice-rafted debris(IRD) content and grain size distribution of sediments,the research reconstructed the paleoenvironmental records over the past~140 ka.The results reveal that the relative abundance of Neogloboquadrina pachyderma(sinistral) is very good negative correlation with Globigerina bulloides,and both of the two species can be used as the sea paleotemperature proxy compared with the curve of oxygen isotopes.The absolute abundance of the planktonic foraminifera,opal content and organic carbon content show that the climate variation of the study area is obviously affected by glacial-interglacial cycle,and the paleoproductivity in the interglacial period was relatively higher than in the glacial period.The analysis of IRD and sediment grain size indicates that the coarse grain content of the southern Okhotsk Sea in the interglacial period was higher than in the glacial period.