南海中南部表层沉积物类型、分布与水动力条件

Type,Distribution and Hydrodynamic Condition of Seafloor Sediments in the Middle and Southern Parts of South China Sea

本文利用南海中南部8°～12°N,108°40′～114°E区域内获取的222个测站的海底沉积物样品的测试数据,并依据福克-沃德确定的沉积物分类方案,将该区沉积物划分为陆源碎屑沉积、生物碎屑-陆源碎屑沉积和生物碎屑沉积三大类,在此基础上研究了沉积物类型特征和分布范围,以及水动力条件等特征。南海中南部沉积物组分以陆源成分和生物成分为主,其分布具有一定的规律性。从陆架到陆坡直至深海盆,沉积物由粗变细,物质组成则由陆源碎屑沉积渐变为生物碎屑-陆源碎屑沉积、生物碎屑沉积。沉积物核心粒级为生物泥和生物粘土,其次为细砂、砂质泥等,其他粒级成分所占比例较小。水动力条件与水深和地形变化等因素相关,水动力强度具有不明显的自西而东逐渐减弱的趋势。

The types of the seafloor sediment in the middle and southern parts of South China Sea have been generally divided into three types： terrestrial clastic sediment, terrestrial/biogen- ic clastic sediment and biogenic clastic sediment in this paper, according to the Folk R L＇s sedi- ment classification and the detail data, which is gained by analyzing the samples located in 8°- 12°N, 108 °0- 114° E of South China Sea. And then the type, distribution and sedimentary hydrodynamic condition of the seafloor sediment in this area have been researched on the basis of these results. The terrestrial clastic and biogenic clastic component of the sediment is predom- inant. The distribution of different sediment types is of orderliness in some extent. For exam- pie, from shelf to slope, and then to deep basin, the size of sediment granularity is gradually decreasing and the sediment component is changing from terrestrial clastic deposition into terres- trial/biogenic classic deposition and then into biogenic deposition. Biogenic mud and biogenic clay account for the majority of the sediment composition, fine sand and sandy mud are follow- ing, and the others account for a small proportion. Sedimentary hydrodynamic condition varies in intention with sea water depth and topography and the hydrodynamic intension is gradually weakening from west to east.