【摘要】 琼东南盆地陆坡深水区晚中新世以来的地层中有比较明显的BSR(似海底反射)分布。由于BSR是识别天然气水合物存在与否的重要地球物理参考标志,而构造变动是影响其分布的重要因素之一。本文结合南海发生的构造运动以及全球和莺—琼盆地海平面相对变化,以11.6 Ma,5.3 Ma和1.8 Ma 3个时间点为界,将琼东南深水区晚中新世以来的地层划分为3个层,自下而上分别为层序Ⅲ、层序Ⅱ、层序Ⅰ。通过对工区二维地震资料301个虚拟点进行盆地模拟,结果表明,3个层序存在构造沉降加速的过程。其中层序Ⅲ构造沉降速率变化相对最为缓慢,层序Ⅱ构造沉降速率整体增大,同时其变化加剧;层序Ⅰ构造沉降速率变化剧烈,最高沉降速率增至170 m/Ma。但是5.3 Ma以来的构造沉降加速在时空上存在东西的差异。空间上构造沉降速率呈周边向中心地带递增的规律。研究区BSR主要分布在各凹陷与凸起次级构造单元相接、构造沉降速率在70～110 m/Ma且变化迅速的区域。更多还原

【Abstract】 BSR found in the formation has been distributed since Late Miocene in the deep water area of Qiongdongnan (Southeast Hainan) Basin, influenced by the tectonic movements. The BSR is one of the important indicators to identify gas hydrate. Based on data analyses from 301 virtual points, the authors worked out the relationship between the BSR’s distribution and the tectonic subsidence. The study shows that under the influence of the Red River strike slip motion and mantle-derived basic magma eruption, there are three different tectonic subsidence acceleration periods bounded by 5.3Ma and 1.8Ma in the deep water area of the Qiongdongnan Basin, of which the third phase (since 1.8Ma) is the fastest stage. From border to center, the tectonic subsidence rate is getting higher and higher, and it changes faster in the central hollow zone than in the southern uplift zone. In the area between them it remains high. BSR is mainly observed in the borderland between secondary structure unit where the tectonic subsidence rate is high and changes faster and the area which can afford higher tectonic subsidence rates varying from 70m/Ma to 110m/Ma.更多还原