南海中南部表层沉积物黏土矿物分布及控制因素

DISTRIBUTION CHARACTERISTICS AND CONTROLLING FACTORS OF CLAY MINERALS IN SURFACE SEDIMENTS FROM THE CENTRAL AND SOUTHERN SOUTH CHINA SEA

利用南海中南部表层沉积物151个样品中黏土矿物的测试数据,计算了主要黏土矿物含量的平均值并编制分布图,据此分析黏土矿物的分布特征及其控制因素。南海中南部表层沉积物中的黏土矿物组合类型为伊利石-蒙脱石-高岭石-绿泥石,含量平均值依次为47%、19%、17%和16%。高岭石含量分布具有北部低、南部高的特点,与之对应的是蒙脱石矿物含量呈现北部高、南部低的趋势。伊利石和绿泥石含量分布规律不甚明显。前者呈现北部略高、南部稍低的分布趋势,含量变化起伏较大;后者的含量变化呈西北陆坡区稍偏低,其他部位含量分布均匀的趋势。伊利石/高岭石含量的比值变化与高岭石含量变化呈明显的负相关关系。从黏土矿物含量的分布规律来看,控制本区黏土矿物分布的主要因素有物源的搬运和输送、水动力条件变化、海底火山活动、地球化学环境影响等。

Based on clay mineral analysis data obtained from 151 surface sampling sites in the central and southern South China Sea, the average percent contents of four clay minerals have been accounted and the clay minerals percent content distribution have been illustrated on maps in this paper. And then, the distribution characteristics and their controlling factors have been interpreted. Clay minerals in the surface sediments of the central and southern South China Sea are illite, smectite, kaolinite and chlorite and their average percent contents are in tune 47%, 19%, 17% and 16%. Kaolinite percent content is low in the north and high in the south, and to the opposite, smectite, hige in the north and low in the south. Illite and chlorite percent content distributions have no obvious regularity. The distribution of the former goes a little higher in the north than in the south with large percent content undulation,and that of the latter is almost the same and only the difference is that the content is lower in the northwest. In addition, the ratio of illite/kaolinite percent content shows a negative interrelation with kaolinite percent content. The main factors that control the average percent content distributions of clay minerals are transportation of continental material, the variation of hydrodynamic condition, seabed volcano activities and geochemical environment.