崖19-1-1井晚第三纪浮游有孔虫深度分层及其古海洋学意义

DEPTH STRATIFICATION OF LATE TERTIARY PLANKTONIC FORAMINIFERA AND THEIR IMPLICATIONS OF WELL YA 19-1-1

依据ＧｅｒｔａＫｅｌｅｒ和Ｇａｓｐｅｒｉ，Ｋｅｎｎｅｔｔ有关中新世印度洋和太平洋浅层水、中层水和深层水浮游有孔虫深度分层组合的划分模式，对南海琼东南盆地崖１９－１－１井晚第三纪浮游有孔虫作了定量研究，并分析了陆架海区浮游有孔虫不同深度分层组合含量的变化与古地理环境变迁的关系。崖１９－１－１井以浅层水、中层水组合为主，深层水组合不发育，反映本区温跃层不发育，不利深层水浮游有孔虫的生存。滨海区，浮游有孔虫仅为少数几个浅层水的优势种，中层水浮游有孔虫不发育；内浅海区，浅层水浮游有孔虫占绝对优势，中层水浮游有孔虫处于次要地位，所含比例相对较小；外浅海区及陆坡半深海区，浅层水和中层水浮游有孔虫均较发育，中层水浮游有孔虫百分含量相对较高。崖１９－１－１井在上新世早中期曾出现外浅海至陆坡半深海区。

According to the classification model of depth stratification of planktonic foraminifera in Miocene Indo-Pacific Ocean (Keller,1985;Gasperi & Kennett,1993), Later Tertiary planktonic foraminiferal species from Ya19-1-1 oil well in Qiongdongnan basin of the northern part of South China Sea could be grouped into the shallow,intermidiate and deep water dwelling groups.There existed a good relationship between percentage changes of these three planktonic foraminifera groups and paleogeographic distributions.Planktonic foraminifera from sediments of Ya19-1-1 are dominated by shallow and intermidiate water dwelling species. The deep water dwelling species are only found in few samples,indicating that sea water was not deep enough for deep water dwelling species or the thermocline was too deep during Late Tertiary in the site of Ya19-1-1.Planktonic foraminifera from the littoral sediments are dominated by a few shallow water dwelling species; Those from inner neritic sediments are characterized by a relative high percentage of shallow water dwelling species and a low percentage of intermidiate water dwelling species;Those from outer neritic or bathyal sediments are characterized by a relative high percentage of intermidiate water dwelling species. Outer neritic or bathyal environment have taken placed in Middle and Lower Pliocene in the site of Ya19-1-1 oil well.