南海西部表层沉积物黏土矿物的分布

对南海西部表层沉积物进行系统取样分析表明,该区黏土矿物总体以伊利石为主,平均含量超过50%,其次为蒙脱石、绿泥石和高岭石含量较低,伊利石和蒙脱石含量变化较大,两者呈负相关关系,而绿泥石和高岭石含量变化较小,两者呈正相关关系。根据黏土矿物组合及其分布特征,南海西部海域大致可以分为A、B、C、D四区,其中A区以高伊利石和低蒙脱石含量为特征,B区伊利石含量明显下降,蒙脱石含量增多,C区以较高蒙脱石含量和低绿泥石、高岭石含量为特征,D区为相对低伊利石,高蒙脱石、绿泥石和高岭石,且往东南方向蒙脱石含量增大,而伊利石含量下降。与邻区黏土矿物组合对比研究表明,高伊利石含量的A区物源,除来自华南大陆的珠江、韩江等大小河流外,可能有相当部分来自东北方向,包括台湾岛及台湾海峡等。越南岸外的陆坡区细粒沉积物与陆架区有明显的继承性,表明其物源主要来自中南半岛,而红河物源对陆坡及深海盆的影响相对较小。南部陆架-陆坡区的物源主要有湄公河和加里曼丹岛,但两者的混合明显。因此,从区域分布来看,来自台湾海峡的细粒沉积物对南海深海盆影响最大,这可能主要是有由于表层环流所致。

CLAY MINERALS DISTRIBUTION IN SURFACE SEDIMENTS IN WESTERN SOUTH CHINA SEA AND PROVENANCE

257 surface sediment samples were collected from the western South China Sea(SCS),covering the shelf,slope to the deep sea basin,and analyzed for clay minerals.The results showed predominance by illite,with average content of more than 50% in the all area.The percentages of illite and smectite in clay minerals change much more significantly than those of chlorite and kaolinite.The illite content displays a distinctly positive relationship with that of smectite,while chlorite content is negatively related to that of kaolinite.Based on the assemblages of clay minerals and their distribution,4 provinces of A,B,C and D were discriminated in the research area.Province A is characterized by very high content of illite and low content of smectite;the percentage of illite in Province B is lower than in Province A but that of smectite is higher.There is relative higher content of smectite and lower content in Province C,and lower content of illite and higher content of smectite,chlorite and kaolinite in Province D.By a comparison with adjacent areas,the assemblage of clay minerals in Province A is more similar to that in Taiwan Strait and Yangtze River and in the estuary of the Pearl River and Hanjiang River.It is suggested that not only sediment from the southern China continent,but that from Taiwan Strait may pay an important role.The provenance of Province C should be mainly from the Indo-China Peninsula,as the assemblage of clay minerals is similar to that in the Vietnam Shelf.The provenance of the southern shelf and slope should include the Mekong River and Kalimantan Islands.