关键词: 下扬子区;基底拆离;逆冲褶皱;走滑拉分;伸展拆离

Abstract:

Paleozoic sea facies basins including North JiangsuSouth Yellow Sea area have undergone three episodes of tectonic transformation and deformation 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, in which the MesoPaleozoic marine basins underwent thrustingfolding deformation with progressively decreasing intensity, which is caused by the SENW overthrust of the decoupling body of JiangnanXuefeng basement（with the induced SN and EW overthrusting) and the transformation of faulted depression with resilient relaxation at the trailing edge. The second episode occurred in the Yanshan epoch from the Late Jurassic to the Early Cretaceous, in which the basins were superposed by the simple shear caused by the NNEtrending horizontal strikeslip structures (represented by the TanLu fracture zone) and the deformation induced by pullapart and faulting tectonic mechanism. The last episode occurred in the Himalayan epoch from the Late Cretaceous to the Paleogene, in which the lower Yangtze area underwent the transformation and deformation caused by the SN extension and detachment as well as domino type of pullingapart and faulting structures. These three episodes of transformation and deformation facilitated the early accumulation, later thermal evolution and redistribution of marine oil and gas in the Yangtze Plate. This paper discusses the three episodes of tectonic transformation and deformation of the Paleozoic sea facies basins in lower Yangtze area since the end of the Middle Triassic.

Key words:

Key words: lower Yangtze area; basement detachment; thrustingfolding; strikeslip and pullapart; extension and detachment