CHARACTERISTICS AND DEPOSITIONAL MODEL OF THE FAULT-CONTROLLED BOTTOM-CURRENT DRIFT DEPOSITS IN THEBEIKANG BASIN, SOUTHERN SOUTH CHINA SEA

Abstract

Bottom current is a significant depositional process in deep sea, by which sediments can be directly transported to form contourite drifts on seafloor. Among the different types of contourite drifts, fault-controlled drifts are not well constrained and few studies have been devoted to their morphological features and depositional patterns. This study is to summarize the features for seismic identification of fault-controlled drifts based on high-resolution multibeam bathymetric and seismic data from the Beikang Basin, southern South China Sea. Two sub-types of fault-controlled drifts, i.e. the syn-depositional and post-depositional fault-controlled drifts are recognized. Their formation mechanism and relationships with faulting are discussed in this paper. According to the interaction between faulting and bottom-current processes the bottom currents can be divided into two types: 1) bottom currents simultaneous to the fault movement, generating the synchronous fault-controlled drifts; 2) bottom currents after the fault movement generating the post-depositional drifts. However, the researches conducted so far are limited to the drift deposits related to normal faults. More researches are required for the drifts formed in other active tectonic settings, such as those related to strike-slip faults and reverse faults.