摘要
海槽表层沉积物沉积特征的研究结果表明,冲绳海槽沉积物具有大陆和大洋之间的过渡性质,大陆及大陆架物质在近期地质历史中,始终是海槽沉积物的主要物质来源;海槽区粗粒沉积物是陆架粗粒沉积物的延续,其性质与陆架区的相似,属于再沉积形成的沉积物;沉积物中的火山物质是区分陆架和海槽沉积物的主要标志之一。
Situated between the continental shelf and Ryukyu Islands, Okinawa Trough is a long narrow backarc sedimentary basin in which there is a transition type of neritic and deep-sea se diments.This type of sediments has the composition of terrigenous and biogenic deposits as well as authigenic minerals and volcanic materials. The terrigenous sands, including quartz and feldspar, are mainly distributed on the Trough border, especially on the west side, while the mud concentrated on the bottom. Dominated by foraminifera, the biogenic components are thickly populated on the west slope because Kuroshio current crosses the area. The volcanic detritus, which comprise pumice and glass, are almost located on the east side and at the bottom, reflecting that there are volcanic activities in these places and' nearby. The glauconite and manganese nodules are also found in the Trough separately.Basing on not only detrital and clay minerals but also chemical elements, the terrigenous deposits are dominant in the Trough, but a large amount of biogenic components, authigenic minerals and some elements show some features of deep-sea sediments. The recent shallow water shells in the depth of 338 m and the sands of 820 m may indicate that some of the sediments are resedimented by some geological agents, such as turbidity current. The mud sediments is slowly transported, and then deposited there.The sedimentary rate for Ra226 is about 3.5 cm per thousand years on the average. The rate in the west slope is higher than in the east and the lowest rate is in the bottom.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
1989年第2期113-121,共9页
Oceanologia Et Limnologia Sinica
