北极圈海域表层沉积物的黏土矿物特征及其环境意义

应用X射线衍射(XRD)分析技术对北极圈海域15个表层沉积物的黏土矿物进行了研究。结合伊利石的结晶度指数综合分析了研究区黏土矿物的组成和分布特征及其物质来源、沉积环境和水动力条件。结果表明,北极圈海域研究区的黏土矿物以伊利石为主(33%),其次为伊/蒙间层矿物(25%)、绿泥石(23%)、高岭石(15%)以及蒙皂石(4%)。伊利石的开形指数(Ns)都比较小,大多在1~2之间,Ns的分布对物源有一定的指示意义。楚科奇海区具较弱的水动力条件,沉积环境较稳定;白令海具强烈的水动力条件,属于冲刷环境。认为北极圈海域研究区的黏土沉积物均有三方面来源,即河流输入、海洋自生和冰筏搬运物。

CLAY MINERALS IN SURFACE SEDIMENTS FROM ARCTIC OCEAN AND THEIR ENVIRONMENTAL SIGNIFICANCE

Fifteen surface sediment sample from Arctic Ocean were analyzed using X-ray diffraction(XRD) technique to determine their clay mineral compositions as well as illite crystallinity index.The distribution pattern of clay minerals and the illite crystallinity index(Ns) of the study area are shown,and the sources of clay minerals,sedimentary environments and hydrodynamic conditions are discussed.The clay minerals are dominated by illite(33%),followed by illite / smectite(25%),chlorite(23%),kaolinite(15%),and smectite(4%).The illite crystallinity index of the study area is low(mostly between 1~2).It is suggested that the crystallinity index of illite is a good indicator for the source of clay minerals.The Chukchi Sea has relatively weak hydrodynamic condition with stable sedimentary environment,while Bering Sea has stronger hydrodynamic condition with erosional sedimentary environment.The sources of the sediments in the Arctic Ocean are mainly from river input,and authigenic clay mineral and ice-rafted materials also make part contributions.