Abstract:

Neotectonic movements in offshore China are mainly represented by unconformities that occurred by the end of Miocene and between Pliocene and Quaternary, subsidence and migration of depocenter during Miocene and Quaternary, well development of late faulting,active earthquake,and various structural traps resulting from Neotectonism.Neotectonism is contributed to changes of regional stress field caused by various factors,such as recent plate movement,replacement and migration of crust and mantle in deep earth,slumping and depressing of sedimentary bodies in transitional zone between shelf and continental slope,and rapid subsidence of basins.Terrain deformation or faulting occurred in some areas where stress concentration resulted in losing equilibrium. Neotectonism in offshore China adjusted and controlled hydrocarbon accumulation and field distribution in each petroliferous basin.Neotectonism in Bohai Bay basin controlled late hydrocarbon accumulation in Bozhong depression and surrounding areas;diapirism in Yingehai basin controlled late gas accumulation;neotectonism in Zhujiangkou basin controlled gas accumulation in the northern slope zone of Zhu Ⅱ depression;while that in Xihu depression partially disrupted oil and gas reservoirs.

Key words: Neotectonism, late accumulation, offshore China, tectonic origin