南海北部西侧海域粘土矿物的含量分布特征及来源分析

应用X射线衍射(XRD)方法对南海北部西侧海域315个表层沉积物<2μm的粘土组分进行分析.结果表明,本研究区粘土矿物有伊利石、绿泥石、蒙脱石和高岭石,其组合特征在不同区域表现出明显的差异.根据粘土矿物的空间分布特征以及研究区的海底地形特征,研究区大致可以分为3个不同区块:A区是珠江口外的大陆架区域;B区是海南岛以东陆架陆坡区域;C区为西沙海槽至西沙群岛附近区域.根据研究区表层粘土矿物分布特征、周围河流供给的主要粘土成分以及洋流搬运作用,发现A区高岭石(平均含量为19%)主要来自珠江,伊利石与绿泥石(平均含量分别为53%和18%)主要由台湾的河流提供,有珠江物质的混合,蒙脱石含量较低(平均含量为10%).B区的高岭石(平均含量为13%)主要由海南岛的河流提供,蒙脱石(平均含量为16%)主要由吕宋岛的河流提供,B区东部的伊利石和绿泥石来自台湾的河流,B区西部伊利石和绿泥石主要来自红河、越南中部河流,海南岛物源亦有贡献.C区高岭石含量较低(平均含量为12%),越南中部河流和红河为C区蒙脱石(平均含量为14%)的主要物源区,C区东部伊利石和绿泥石来自台湾的河流,C区西部伊利石和绿泥石主要来自红河、越南中部河流.

Distribution characteristics and source analysis of clay minerals contents in surface sediments of the northwestern South China Sea

Clay components2 μm of 315 surface sediment samples are analyzed by XRD.The results indicate that clay minerals consist of illite,chlorite,smectite and kaolinite.Distribution character of the clay minerals is significantly different in different parts of the research area.Based on the distribution character of clay minerals and topography of the research area,the research area can be divided into three parts： A area is the continental shelf off Pearl River;B area is the eastern continental shelf and the slope off the Hainan Island;C area is from Xisha Trough to the Xisha Islands waters.Based on the distribution characteristics of the clay minerals in the research area and surrounding rivers,it is found that kaolinite（mean 19%）of A area is from Pearl River,illite（mean 53%） and chlorite（mean 18%） mainly from Taiwan,with low amount of smectite（mean 10%）.Kaolinite（mean 13%） of B area is mainly from Hainan Island,smectite（mean 16%） mainly from Luzon Island.Smectite（mean 14%） of C area is mainly from rivers of middle Vietnam and the Red River,with low（mean 12%） kaolinite content.Illite and chlorite of west B and C area are mainly from rivers of middle Vietnam and the Red River,while illite and chlorite of east B and C area are mainly from Taiwan rivers.