南黄海埋藏古河系研究

STUDY ON BURIED PALEO-CHANNEL SYSTEM IN THE SOUTH YELLOW SEA

1987—1989年浅地层测量结果表明,南黄海海底存在许多埋藏古河道、古湖泊、古三角洲,它们组成一个完整的水系。据矿物分析和化学成分分析,北部的古河道为古黄河水系,南部的为古长江水系,二者有可能一度汇合于南黄海中部。它们可能形成于2.5—0.9万年以前的低海面时期。成山角东部的下部地层中发现更老的古河道,可能为中更新世古黄河河床。在南黄海中部80m水深处发现了低海面时期的古黄河、古长江三角洲,那里约为2.5万年以前的古海岸线。

Investigation of sub-strata profiles shows that there are many buried paleo-channels, paleo-lakes, and paleo-delta which made up integrated paleo-water system in the South Yellow Sea. According to data of chemical and mineral composition of sediments, the northern part belongs to the paleo-Yellow River system and the southern part to the Changjiang River system, and both converged in the center of the South Yellow Sea. They were formed from 2.5 to 0.9×104 a B. P. during the end of late pleistocene. Older and larger buried paleo-channel, which might be paleo-Yellow River formed during middle Pleistocene was found in lower strata at the place east to the Chengshanjiao Cape. In addition onlape strata representing paleo coastline system was discovered near the isobath of 50 m corresponding with the relict sediment in the Haizhou Bay. At isobath of about 80 m large buried paleo-delta with complex cross bedding sequences was found in the center part of the South Yellow Sea. It represens another paleo-coastline system during 2.5×104a B. P. during regression period.