南海北部珠江口外峡谷体系沉积特征、演化及其控制因素

深水海底峡谷内部的粗粒碎屑沉积物不仅可以作为良好的油气储层，也可以较为完整地记录海洋地质环境变迁的相关信息，是目前海洋地质领域研究的热点.为揭示南海北部珠江口外峡谷体系沉积演化过程及其控制因素，利用多波束测深和高分辨率二维多道地震数据，对珠江口外峡谷体系地形特征、沉积充填特征、形成发育过程和控制因素进行研究.研究发现珠江口外峡谷呈三段式发育:上段为NW-SE走向，宽度超过30 km，侵蚀强度不大，横截面为不规则形态；中段为E-W走向，宽度开始变窄（25~30 km），横截面呈U型；下段为NW-SE走向，宽度达到最大（25~45 km），横截面呈U型，中段和下段以沉积作用为主.珠江口外峡谷体系沉积演化主要分为3个阶段:早期阶段（23~15.5 Ma），水道?海底扇阶段（15.5~11.6 Ma）和峡谷?海底扇/块体流阶段（11.6~0 Ma）.揭示了该峡谷珠江口外峡谷体系的发育和演化主要受构造运动、海平面变化和沉积物供给的控制作用，通过以上分析，将对南海北部海洋灾害地质、深水沉积体系研究及油气资源勘探有重要的指导意义. 

Sedimentary Characteristics,Evolution and Controlling Factors of the Pearl River Canyon System in the Northern South China Sea

The coarser clastic sediment in deep-water submarine canyons is a hot topic in the field of marine geology, not only because it can be good oil and gas reservoirs, but also because it records the complete information of marine geological environment change. In order to reveal the sedimentary evolution process and controlling factors of the Pearl River Canyon system, in this paper it combined multibeam bathymetric and high resolution 2D multi-channel seismic data to study the topography characteristics, sedimentary filling characteristics, the formation processes and controlling factors of the Pearl River Canyon system. The study shows that Pearl River Canyon system has developed in three sections. The upper section is in NW-SE trend, with a width of more than 30 km, low erosion intensity, and irregular cross section. The middle section is in E-W trend, with narrower width (25-30 km), and U-shaped cross section. The lower sections is in NW-SE trend with the largest width (25-45 km) and U-shaped cross section. The middle and the lower sections are dominated by sedimentation. The evolution of Pearl River Canyon system could be divided into three stages: the early stage (23-15.5 Ma), the channel-submarine fan form stage (15.5-11.6 Ma) and the canyon-submarine fan/block flow stage (11.6-0 Ma). It's revealed that the development and evolution of the Pearl River Canyon system are mainly controlled by tectonic movement, sea level change and sediment supply. The above analysis has practical significance for the study of marine disaster, deep-water depositional system and hydrocarbon resources exploration in the northern South China Sea.