拟通过中国东海相对海平面与全球海平面对比分析,来获得东海构造沉降数据。但在对比分析的过程中发现,断裂作用对中国东海150m以深海域相对海平面的变化有重要影响。这种作用使东海150m以深海底至少下降了30m,这是我国学者先前误认为中国东海末次冰盛期最低海面位置位于现今海面下150~160m一带的主要原因。在此基础上,进一步对水与冰川重力均衡、沉积物压实和构造沉降作用进行了探讨。结果认为重力均衡不足、沉积物压实作用微弱,构造沉降是造成东海相对海平面与全球海面之间差异的又一重要原因。同时发现东海构造沉降随水深呈规律性变化。断裂作用的表现结果所赋予的更深层次的思考与认识是,在17kaB.P.以前,中国东海水深150~160m一带是1个相对隆起带,其存在对陆架区圈闭和捕获中国大陆古水系和沉积物具有重要意义。
The original intention of this study was to obtain the tectonic subsidence parameters for the East China Sea(ECS) by comparing relative sea level curve of the ECS with the eustacy curve. But in the course of comparing and analyzing, it was discovered that rifting has a significant effect on the relative sea level changes in the ECS in areas with water depths greater than 150 m. The rifting caused the sea in those areas to descend by at least 30 m, which is the main reason that some Chinese researchers mistake the water depth between 150 m and 160m for the lowest sea level position during the Last Glacial Maximum. Based on the above discoveries, we further studied the isostasy, sediment compaction and tectonic subsidence in this area, and found that insufficient isostasy, weak sediment compaction and tectonic subsidence was another significant reason that caused the difference between the sea level curve of the ECS and the eustacy curve. At the same time, we found that the tectonic subsidence changed regularly with the water depth in the ECS shelf. The results caused by rifting imply that the area with depths between 150 m and 160 m was a relative swell belt before 17 ka B.P. and the existence of the belt was of significance in entrapping and capturing sediments from the land of China.