南海现代沉积地质学的若干问题

Discussions on recent sedimentary geology in South China Sea

本文根据大量实际调查资料,从地质学和海洋沉积学角度,论述南海现代沉积地质学7方面的规律问题,获得初步认识是:(1) 沉积物有8种沉积成因类型,5种沉积环境和相,及具有3次海退、海进旋回的沉积演化模式;(2) 沉积成因类型以陆源碎屑和生物源为主;(3) 生物沉积是判别沉积环境和相的重要标志。沉积物粒度特征,是反映主要水动力作用的可靠标志;(4) 海洋有用砂矿物和锰结核的沉积,受沉积成因类型和沉积环境所控制。

Based on multidisciplinary investigations and analyses, this paper discussies the sedimentary characteristics and depositional laws in the South China Sea. The major results are as follows: (1) In the region there are mainly eight sedimentary types, five sedimentary environments and five sedimentary facies. On the continental shelf the sediments may be classified into tbree transgression series and three regression series, representing six stages of the development models. (2) Major genetic types in the re gion are terrigenous and biogenic ones followed by biogenic-terrigenous and volcanie-biogenic-terrigenous types. (3) The biogenic detritus are made of remains of coral, bivalve, gastropoda, foraminifera, ostracoda, diatom etc. Usually, they are important indicators of sedimentary facies. (4) On the continental shelf, the grain size characteristics and distributions reflect complicated hydrodynamics of the different environments. The changes of the grain size of the sediments are the indications of the different hydrodynamic conditions. (5) The sedimentation of minerals and chemical compositions of sedi ments show that the forming of placer and Mn nodules are controlled by the genetic types of the sediments and it's sedimentary environments.