Deep-water depositional characteristics and relationship with bottom currents at the intersection of Xi’sha Trough and Northwest Sub-Basin, South China Sea

Simulated flow field characteristics at 2000m depth, at the intersection of the Xi’sha Trough and the Northwest Sub-Basin, show a major anticyclonic gyre. These westward flowing deep currents sweep the South China Sea northern margins until they encounter the Xi’sha Trough and the Xi’sha Uplift. Some of them flow into the Xi’sha Trough and continue going westwards; others change their heading towards to the south and sweep the Xi’sha Uplift eastern margins. In the eastern margins, current velocities could exceed 2cm.s-1 as a result of bottom current intensification (after being deflected by the uplifted morphology). Hydrodynamics over the remaining parts of the Xi’sha Uplift zone (south of the Xi’sha Trough) are complex. Fortunately, high-resolution 2D seismic data enable to reveal the depositional characteristics of bottom currents below 1800m depth in this area, whereas marginal troughs and confined drifts are recognized in the vicinity of the obstacle terrains. Major troughs formed north of those obstacles, indicating mainly westward flowing bottom currents in this area. This study focuses on the analysis of deep-water depositional products, created by bottom currents and the relationship with the South China Sea Deep Water Circulation