南海东部海域表层沉积物类型的研究

Research on surface sediment types and distributions from the eastern South China Sea, China

南海东部海域表层沉积物可被分为11种类型:含岩块砾石黏土质粉砂、贝壳珊瑚砂、黏土质粉砂、钙质黏土、钙质软泥、有孔虫砂、深海黏土、含铁锰微粒粉砂质黏土、硅质黏土、含火山灰硅质黏土、含火山灰粉砂质黏土.这些类型按物源和成因可被分为陆源碎屑、钙质碎屑和硅质碎屑、火山碎屑3大类型,其中陆源碎屑分布面积约占50%,钙质碎屑占20%,硅质碎屑和火山碎屑各占15%.在物质来源、海底地形、火山作用、生物作用、水动力条件等因素影响和控制下,由于沉积环境的差异,故区内褐色类沉积物最多(60 68%),灰色类沉积物次之(38 20%),黄色类沉积物最少(1 12%).台湾省以南到17°N以北海区沉积物以陆源沉积物分布为主;巴士海峡以西海区沉积物较粗,常含砂岩块和砾石;东沙群岛以东海区钙质生物碎屑沉积丰富;中、西部海区以含铁锰微粒沉积物为主;中、南部海区水深大,主要分布硅质沉积物;南部海区、礼乐滩北缘沉积物受礼乐滩珊瑚碎屑影响大,沉积物类型为钙质软泥.

The surface sediments in the eastern South China Sea can be divided into 11 types based on the data of sediment color, grain size analysis, chemical and mineral compositions, microfossils, etc. These sediment types are named as clayey silt with rock debris, shell sand, clayey silt, calcareous clay, calcareous ooze, foraminifer ooze, pelagic clay, silty clay with micro-manganese nodules, siliceous clay, siliceous clay with volcanic ash, silty clay with volcanic ash. These sediments can be attributed into terrigenous, biogenic and volcanogenic, according to their material source and genetic environments of sediments. Of which, terrigenous sediments cover 50% area of sea bottom in the study area, calcareous debris 20%, siliceous debris and volcanogenic sediments 15% respectively. Under being controlled and affected by the factors such as material source, seabed feature, volcanic eruption and organism activity, hydraulic conditions, as well as the different depositional environments, the brown sediments are dominated (60.68%), the second is the grey sediments(38.20%),the last is the yellow sediments(1.12%) in the study area. In the sea area of between south of Taiwan Province of China and 17°N, the sediments consist mainly of terrigenous constituents; in the west sea area of the Bashi Channel, the coarse sediments are dominated with sandstone rock and gravel; in the east sea area of Dongsha Islands, calcareous debris are enriched; in the central and western parts, the sediments are rich in the micro-manganese nodules; siliceous sediments are widely distributed in the southern and central areas because of deep waters; in the southern part and the north edge of Liyue Bank(Liyue Reef Shoal), sediments are calcareous ooze due to be affected by large quantities of detrital corals.