南黄海盆地北凹多幕正反转构造特征及其动力学分析

利用重处理的二维地震测线对南黄海盆地北凹进行了精细的构造解释，揭示了三种不同类型的正反转构造样式，分别是中南部的逆冲型、东部的压扭型和北部的褶皱型，主要受控于其所处的不同构造位置。通过典型地震测线的平衡剖面分析，并结合区域构造动力学背景分析，认为北凹至少发生了三幕构造正反转，主要受控于不同地质时期太平洋板块对欧亚大陆俯冲速度和角度的改变。其中，三垛组沉积之后，太平洋板块俯冲角度逐步由北西向转为南西西向，并且俯冲速度明显增大，使得北凹处于北东南西向挤压环境中，广泛发育正反转构造，这也是最强烈的一幕正反转，表现为强烈的逆断层活动和地层剥蚀。过度的正反转作用可能对北凹油气藏的形成造成了不利的影响。

Tectonic Characteristics and Dynamical Analysis of Episodic Positive Inversion in the North Sag of South Yellow Sea Basin

Three types of positive inversion structures are found in the North Sag of South Yellow Sea Basin with interpretation of reprocessed 2D seismic data. They are classified into three types: the reversed fault type in the central and southern part, the transpressional type in the eastern part and the compressional fold type in the northern part. Where the inversion structures located was depended on the different tectonic positions. Based on the integrated analysis of balance sections of the typical seismic profiles and the regional tectonic background, it was considered that three episodic positive inversions had happened in the North Sag at least, which were influenced by the change of the subduction angle and rate from the Pacific plate to the Eurasian continent during the Cenozoic period. After the Sanduo Formation deposited, the subduction direction of the Pacific plate changed from NW to SWW and the subduction rate increased twice nearly. This change caused the most intensely positive inversion episode of the North Sag because of the SWW compressional force from the Pacific plate, which presented the strongest reversely faulting and erosion. Meanwhile, the excessively positive inversion may not be good for the hydrocarbon accumulation in the North Sag.