琼东南盆地中央峡谷上新统块体搬运沉积体系地震特征及其分布

SEISMIC CHARACTERISTICS AND DISTRIBUTION OF PLIOCENE MASS TRANSPORT DEPOSITS IN CENTRAL CANYON OF QIONGDONGNAN BASIN

根据琼东南盆地深水区高分辨率2D/3D地震资料精细解释,和基于三维地震资料的相干分析,在琼东南盆地中央峡谷区发现了多期次的块体搬运沉积体系(MTDs)。研究表明,该区域块体搬运沉积体系包括3个主要的结构单元,即头部拉张区、体部滑移区和趾部挤压区,不同位置地震特征不同。大规模的块体搬运沉积体系构成了琼东南盆地中央峡谷区新近系以来地层中的重要沉积单元,并对深海沉积物的空间展布有重要的控制作用。上新世发育的一期块体搬运沉积体系,分布面积达300km2,厚度达240m,平面展布形态似扇形。高沉积物供给速率和不断的构造活动可能是该区域MTDs发育的主要原因。此外,地震活动、海平面变化也间接影响了MTDs的发育。

2D/3D seismic data and coherence of 3D seismic data in the deepwater area of Qiongdongnan Basin reveal the occurrence of multi-stage mass transport deposits（MTDs） in the Central Canyon of the basin.The MTDs of this region consist of three units,namely the headwall domain,the translational domain and the toe domain characterized by different seismic characteristics.Being regarded as an important part of deepwater deposition in the Central Canyon of Qiongdongnan Basin since Neogene,the large-scale MTDs have an important effect on the spatial distribution of sediment in the deepwater basin.The Pliocene MTDs are distributed in an area of 300 km2,with a thickness up to 240 m in a fan shape in planar distribution.The rapid sedimentary discharge and active tectonic movement may be the main reasons for the development of the MTDs in Central Canyon of Qiongdongnan Basin..In addition,earthquakes and fluctuation of sea level have a significant effect on the formation of the MTDs.