西北冰洋表层沉积物黏土矿物分布特征及物质来源

西北冰洋表层沉积物黏土矿物分析结果显示其黏土矿物组成的区域分布和变化具有明显的规律性:从楚科奇海到北冰洋深水区,随着水深的增加,蒙皂石和高岭石含量增高,绿泥石和伊利石含量降低。自西往东,伊利石结晶度值降低,化学指数升高。根据Q型聚类分析获得的黏土矿物组合特征,结合周缘陆地的地质背景、河流及洋流情况,对研究区进行了黏土矿物组合分区,讨论了其黏土矿物来源。楚科奇海表层沉积物黏土矿物组合在靠近阿拉斯加一侧海域以Ⅰ类为主,靠东西伯利亚海一侧主要有Ⅱ类、Ⅲ类和Ⅳ类,中部主要为Ⅵ类,主要是西伯利亚和阿拉斯加的火山岩、变质岩以及一些含高岭石的沉积物以及古土壤等,经风化、河流搬运入海,在北太平洋的3股洋流及西伯利亚沿岸流的作用下沉积形成的。西北冰洋深水区表层沉积物的黏土矿物组合以Ⅰ类和Ⅴ类为主,表明其沉积物来源为欧亚陆架和加拿大北极群岛周缘海域的海冰沉积和大西洋水体的搬运以及加拿大马更些河的河流物质输入。

Distributions and sources of clay minerals in the surface sediments of the western Arctic Ocean

Regional distribution and variation of clay minerals in the study area are presented in detail based on the clay mineral analysis of the surface sediments. Generally, the smectite and kaolinite contents show an increasing trend from the Chukchi Sea to the deep sea of the Arctic ocean , and the chlorite and illite contents show a decreasing trend. In the study area, from west to east, values of illiteChemical index show an increasing trend, and the values of illite crystallinity is in opposite. Based on clay mineral assemblages obtained from Q-type Cluster analysis, combined with the geological background of the peripheral land, rivers and ocean current, we got the clay mineral assemblages partitions of the study area and discussed its clay mineral source. Clay mineral assemblages type near the Alaska of Chukchi Sea side are mainly Ⅰ type, on the side of the East Siberian Sea contain Ⅱ, Ⅲ and Ⅳ types, on the middle of Chukchi Sea are mainly Ⅵ type.The sources of clay mineral assemblages in Chukchi Sea shelf are volcanic rocks, metamorphic rocks, kaolinite-bearing sediments and ancient soil of Siberia and Alaska from rivers emptying into the Pacific and eastern Arctic ocean and then transported into the Chukchi Sea through three branches of the Pacific Water and the Siberian Coastal Current; Clay mineral assemblages of Western Arctic deep water sediments are mainly Ⅰ and Ⅴ type, indicating that the the source of clay mineral assemblages are ice-rafted deris in sea ice of Eurasian continental shelf and periphery waters of the Canadian Arctic Archipelago, in addition, Mackenzie River and the subsurface Atlantic layer circulation can also contribute clay minerals.