SEISMIC CHARACTERISTICS OF QUATERNARY MASS TRANSPORT DEPOSITS IN QIONGDONGNAN BASIN

Mass transport deposits (MTDs)are widely distributed in Quaternary sedimentary sequences of the continental slope in the Qiongdongnan basin, South China Sea. MTDs are a sediment transport mechanism often occurring in the outer-shelf/upper-slope area. MTDs include slide, slump and debris flow. Based on the high resolution deepwater three-dimension seismic data, seismic amplitude and coherence data are obtained. Through the seismic profile, structural map and time slice of target strata, profile characteristics and internal structure of MTDs are revealed. MTDs are characteristic of seismic reflection of mound, hummocky, chaotic, low amplitude and poor continuity. Folds and thrust faults which are attributed to plastic deformation structures occur in MTDs, and folds occur in the main part, thrust faults in the toe part. The high sedimentation rate of Quaternary sequence and the location in the earthquake belt are the trigger mechanism of MTDs in the study area.