南海北部珠江口盆地重力流与等深流交互作用沉积特征、过程及沉积模式

Interactions between Down-Slope and Along-Slope Processes on the Northern Slope of South China Sea:Products,Processes,and Depositional Model

通过地震及钻孔资料对南海北部珠江口盆地重力流及等深流沉积进行了研究。南海北部重力流及等深流沉积类型多样，包括峡谷、单向迁移水道、堤岸、朵叶及漂积体。单向迁移水道迁移方向分别为北东向和南西西向，为重力流与等深流交互作用形成。漂积体有大型长条状漂积体、限制型漂积体和陆坡席状漂积体，岩性为粘土、泥质粉沙。南海北部陆坡水深200-1200m范围内发育北东向迁移水道及小规模的漂积体，而水深约1200～3000m内则以朵叶及大规模的漂积体为主，见少量南西西向迁移水道。其中，漂积体多分布于峡谷、水道及朵叶的两侧，为等深流改造堤岸、朵叶等“细粒”沉积物而成。

Using integrations of seismic data and core data, interactions between down-slope and along-slope processes had been studied. Gravity flow deposits and contourites are well developed in northern South China Sea, including canyon, unidirectionally migrational channels, levees, lobes, drifts and so on. Unidirectionally migrating channels result from interactions between gravity flow and contour current with migrating directions are northeast （NE） and west-southwest （WSW）, respectively. Drifts consisted of clay and muddy silt could be divided into giant elongated, confined and slope sheeted drifts. NE-migrating channels and drifts are widespread at water depths of 200 m to 1 200 m. By contrast, lobes, drifts and few WSW-migrating are developed at depths of 1 200 m to 3 000 m. Contourites distribute on the both sides of canyon, channel and lobe, which result from reworking the fine-grained deposits of gravitv flow.