Analysis on Seismic Characteristics and Triggering Mechanisms of Mass Transport Deposits on the Northern Slope of the South China Sea

Abstract

Abstract Mass transport deposits (MTDs) are one kind of deepwater sedimentary systems driven by the gravity flow action, and play an important role for the deep‐water sedimentation in global continental margins. MTDs are not only one of the most serious deep‐water geo‐hazards, but also have close relationship with the formation and accumulation of marine gas hydrates and deepwater hydrocarbon. Based on the topographic and high resolution seismic data in the hydrocarbon exploration region, we identified the characteristics and distribution of MTDs in the northern slope of the South China Sea. MTDs are characterized by apparent geomorphology and sedimentary structures. In MTDs there are well developed extensional faults in the head and slides and turnover blocks in the middle. Compressive structures and thrust faults are formed in the toe region of MTDs. Several mechanisms can account for development of MTDs. However, Baiyun MTDs were inferred to be dominated by the dissolution of gas hydrate as suggested by the model of gas hydrate reservoirs and numerical modeling using the elastic‐plastic finite element method for MTDs in the Baiyun sag. Six different gas hydrate dissolution models are chosen to calculate the safety factors. We found that the stability of submarine slope decreases with the increasing dissolution of gas hydrate.