扬子板块中、古生代盆地的改造变形

Transformation and deformation of the Meso-Paleozoic basins in the Yangtze Plate

扬子板块内海相中、古生代盆地自中三叠世末以来,经历了3期不同性质构造作用的改造变形。首先是在中三叠世末—早、中侏罗世的印支运动期,江南-雪峰基底拆离体由南东向北西方向(同时派生由南向北,由东向西的方向)的逆冲推覆,以及后缘弹性松弛的断陷构造作用的改造,使得海相中、古生代盆地发生了第Ⅰ期的由强及弱递进衰减的逆冲-褶皱变形。继而在晚侏罗世—早白垩世的燕山运动期,叠加了第Ⅱ期以郯庐断裂带为代表的 NNE 向大陆平移走滑构造的简单剪切,以及拉分断陷构造作用的改造变形。之后在晚白垩世—古近纪的喜马拉雅运动期,下扬子区在由南向北的伸展拆离与多米诺式拉张断陷构造作用下,受到了第Ⅲ期的变形改造。这3期构造变形作用促使了扬子板块海相油气的早期聚集、晚期热演化和再分配。

The Meso-Paleozoic basins in the Yangtze Plate experienced three episodes of transformation and deformation of different tectonic actions since the end of the Middle Triassic. The first episode occurred in the Indo- Chinese epoch from the end of the Middle Triassic to the early Middle Jurassic ,when the SE-NW overthrusting of the Jiangnan-Xuefeng basement detachment body（with the induced S-N and E-W overthrusting）and the transfor- mation of faulted depression with resilient relaxant trailing edge caused the progressively decreasing thrustingfolding deformation of the Meso-Paleozoic marine basins. The second episode occurred in the Yanshan epoch from the Later Jurassic to Early Cretaceous, when the basins were overprinted with simple shear caused by the NNE-trending horizontal strike-slip structures （represented by the Tan-Lu fracture zone）and deformation induced by pull-apart and faulting tectonic mechanisms. The last episode occurred in the Himalayan epoch from the Later Cretaceous to the Paleogene, when the Lower Yangtze area experienced transformation and deformation caused by S-N extension and detachment as well as domino type pulling-apart and faulting structures. These three episodes of transformation and deformation facilitated the early accumulation, later thermal evolution and re-distribution of marine oil and gas in the Yangtze Plate.