东海内陆架泥质区百年来黏土矿物组成变化及其环境意义

摘要

The modern depocenter in the East China Sea is the mud area on the inner shelf,and the clay fraction of the sediments in the area is the main component.In the study of sedimentology,the clay minerals assemblage was widely used as an indicator of provenance and transportation of particulates.In this study,we used the method of XRD to study the variation of clay mineral contents in two gravity cores collected from the mud area.The clay minerals,together with the analysis of grain size and radioactive dating on the samples,have been used to discuss their environmental implications.The result shows that sediments in the mud area of East China Sea are mainly de-rived from the supply of Changjiang River,and contain a little from the Huanghe River and Oujiang River.And, clay mineral records have exhibited significant changes in the last one hundred years,which may be influenced by the fluctuations of East Asian Monsoon and the decreasing of sediment discharge of the Changjiang River.%东海内陆架泥质区是东海现代沉积的“汇”，其中黏土组分是泥质区沉积物的重要组成部分。沉积物中黏土矿物组合是反映沉积区物质来源和搬运动力状况的良好指标。本文利用 XRD 方法分析了东海内陆架泥质区两根沉积物岩心中黏土矿物组成和含量变化，结合放射性年代标定，揭示了近百年来黏土矿物组成的演变特征，探讨了黏土矿物的来源及其含量变化的制约因素。结果表明：东海内陆架泥质区沉积物以长江来源物质为主，受黄河及瓯江等河流物质的影响；近百年来内陆架泥质区黏土矿物组合发生显著阶段性变化，它们是东亚季风强弱波动和长江入海悬沙减少的共同作用的结果。