中文摘要：

三沙海底峡谷是连接西沙碳酸盐台地与南海西北次海盆的深水海底峡谷,起源于永兴岛和东岛之间的浅水区域,输送了大量碳酸盐碎屑到西北次海盆。三沙海底峡谷是迄今为止发现的南海最大碳酸盐型海底峡谷。海底峡谷的横断面呈现V、U字形,可以分为峡谷外侧、斜坡和谷底3个部分。峡谷外侧平缓、两侧斜坡陡峭、谷底平缓。沿着峡谷走向,可以分为上游、中游和下游3部分。上游部分坡度较陡、坡度变化较大,环礁周边的水道和海底滑坡体系是源区的碎屑物质搬运通道;中-下游部分坡度平缓、坡度变化小,主要以碎屑物质的搬运为主,汇入两侧斜坡上的侵蚀、坍塌形成的碎屑,在西北次海盆形成了喇叭状的入海盆口。通过三沙海底峡谷的研究,有助于揭示岛礁与海盆之间的沉积物输送、海底不稳定性等基础科学问题,为碳酸盐岩油气储层预测、岛礁生态旅游开发提供理论基础。

英文摘要：

The Sansha Canyon, as a path for sediment transportation, starts from the shallow waters platform between the Yongxing island and the East island. It brings a large amount of carbonate clastics down to the northwest sub-basin of the South China Sea. It is the largest carbonate type canyon found so far in the South China Sea in typical V and U shape. In the cross section, the canyon can be divided into three parts ,outer side, slope and valley. Both the outer sides and valley bottom are rather gentle, while the slopes are quite steep. The canyon can also be divided into three parts along the pathway, i.e. the upstream, midstream and downstream. The upstream part is steep with high varying slope, while the downstream is opposite. A large amount of mass deposits coming from submarine slides around the atolls are the source area of clastic sediments. On other hand, the midstream and downstream are characterized by gentle bottoms and the deposition of clastics coming from both source area and canyon slopes and finally settle down in a trumpet shape in the northwest sub-basin. The study of Sansha Canyon is helpful to the understanding of sediment delivery mechanism and the formation of deep water carbonate reservoirs between the coral reef platform and a deep sea basin.