西北冰洋楚科奇海台晚第四纪以来陆源沉积物搬运机制及其古环境意义

Transportation mechanism of terrigenous sediment and its paleoenvironmental implications on the Chukchi Plateau,western Arctic Ocean during the late Quaternary

通过对西北冰洋楚科奇海台的ARC7-P12岩心的沉积物颜色旋回、XRF-Ca和Mn元素相对含量,有孔虫丰度,粗组分含量,粒度组成及其端元的综合分析,并与该地区其他沉积物岩心对比,将ARC7-P12岩心划分为深海氧同位素(Marine Isotope Stages,MIS)5期以来的沉积序列。该岩心的粒度端元分析结果显示,该岩心峰态中值2和9μm组分的端元分别代表由雾状层和底流搬运的沉积物;峰态中值为30以及110μm组分的端元代表海冰以及冰山搬运的沉积物。MIS 5以来的冰消期和间冰期,由于海冰和冰山融化以及海域开阔,沉积物主要由海冰以及冰山搬运,粗组分含量显著升高。冰期由于海冰覆盖,冰盖的生长和阻挡,以及表层洋流减弱,底流和雾状层搬运相对增强,细颗粒沉积物增加。

A comprehensive analysis of sediment color cycle,XRF-Ca and Mn content,foraminiferal abundance,coarse fraction content,grain size and end-member modeling analysis have been carried out for the core ARC7-P12 collected from the Chukchi Plateau,Western Arctic Ocean.Stratigraphic correlation indicates that the core ARC7-P12 is deposited in the time from MIS（Marine Isotope Stage）5 to 1.Grain size end-member analysis suggests that the particle modal values of 2μm and9μm represent the nepheloid and deep current transportation respectively,while the particle modal values of 30μm and the110μm represent sea ice and iceberg transportation respectively.Since MIS 5,the interglacial and deglaciation periods was characterized by increase in coarse fraction due to the collapse of ice shelf and the expansion of open sea.Sea ice and iceberg were melted,leading to ice-rafted detritus deposition.During the glacial periods,however,due to the growth of the sea ice cover and ice sheet as well as the weakening of the surface currents,the transportation of deep current and nepheloid was relatively enhanced,and as the results,fine-grained sediment increased.