东海西部海域现代沉积环境分区及沉积特征的初步研究

PRELIMINARY STUDY ON THE MODERN SEDIMENTARYENVIRONMENT AND SEDIMENTARY CHARACTERISTICSIN THE WESTERN PART OF THE EAST CHINA SEA

对本区1040个站位表层沉积物的粒度、矿物、化学及生物组分等特征进行了详尽的分析与研究,据此,把东海西部海域的现代沉积环境划分为两种类型的过渡环境。一类是与河口有关的过渡沉积环境,如长江三角洲沉积区,杭州湾沉积区及混合沉积区;另一类与河口无关的过渡沉积环境,包括浙东近岸沉积区,苏北浅滩沉积区及陆架改造沉积区。

A great deal of data about surficial sediments in the western part of East China Sea(from shoreline to 124°E and from 26° to 32°N) have been obtained by the Bureau of Marine Geological Survey, MGMR since 1978. The study on the grain size, minerals, chemical compositions and biological associations of surficial sediments from 1040 stations shows that the sedimentary environment in the western part of the East China Sea lies between continental and marine environments and is typical of transitional environment. By analysing the data mentioned above, the transitional environment can be divided into two parts. The first part consists of the Changjiang River Delta Depositional Zone, Hangzhou Bay Depositional Zone and the mixed area, which are associated with the estuaries. The second part, which is not related to the estuaries, includes the Zhedong Nearshore Depositional Zone, the Subei Shoal Depositional Zone and the Shelf Reworked Depositional Zone These depositional zones are quite different in sedimentary characteristics, due to the differences of marine hydrodynamic conditions, sediment sources, topographic and geomorphic features and sea-level fluctuations.