Characteristics of Neogene depositional systems on the northern continental slope of the South China Sea and their relationships with gas hydrate

Abstract：The Cenozoic on the northern continental slope of the South China Sea contains abundant petroleum and other mineral resources, so an analysis of its depositional systems can help geologists to guide resource exploration and exploitation. On the basis of the interpretation and study of seismic sections in the Xisha trough and Dongsha sea area on the northern slope of the South China Sea and in light of the seismic facies classification principle of external geometric shape plus internal reflector configuration, eight typical seismic facies are recognized in sedimentary beds since the Miocene; they are: sheet-parallel, sheet-wavy, sheet-blank, sheet-chaotic, sheet-foreset, brush-shaped foreset, lenticular foreset and mound-chaotic facies. On that basis, six depositional systems are recognized on the northern slope of the South China Sea; they are: delta, contourite, submarine fan or slope fan, slump block, turbidite fan and fan-delta. Of these, the distribution of the contourite, slump block and fronts of deltas or fans is highly consistent with the distribution of BSR, and thus they are the most favorable facies for gas hydrate accumulation.