中国近海含油气盆地新构造运动与油气成藏

Neotectonics and Petroleum Accumulation in Offshore Chinese Basins

自中新世末 (大约 5 .2Ma)至今是中国近海新生代盆地裂后热沉降最活跃的时期 ,并伴随着裂后构造再活动 .这一期构造运动 ,即本文所定义的新构造运动 ,调整和控制了各含油气盆地的油气最终成藏和油气田的定型分布 .阐述了新构造运动的概念、识别依据、成因机制以及对油气藏形成的控制 .在中国近海 ,新构造运动的主要表现包括中新统末、上新统与第四系之间及层系内部的不整合、中新世和第四纪沉降、沉积中心的迁移、非常发育的晚期断裂活动及活跃的天然地震等 .不同盆地新构造运动的强度、发育机制不同 ,其对油气成藏与分布的控制亦不同 .以渤海湾盆地渤中坳陷、莺歌海盆地和东海盆地西湖坳陷为例 ,系统地论述了中国近海新构造运动对油气藏形成的控制和影响 .渤海新构造运动控制了渤中坳陷及其周围油气晚期成藏 ,莺歌海盆地底辟活动控制了天然气晚期成藏 。

The Tertiary offshore Chinese basins have been undergoing the most rapid post-rift thermal subsidence since the end of the Miocene (about 5.2 Ma). The thermal subsidence is accompanied by tectonic re-activation. Tectonic movements, i.e. the neotectonics as defined in this paper, modify and control the ultimate petroleum accumulation and distribution in these offshore petroleum-bearing basins. The concept, distinguishing characteristics, genetic mechanism of the neotectonics as well as their controlling role on petroleum accumulation are presented and discussed in this paper. The main manifestations of the neotectonics in the offshore Chinese basins include the formation of unconformities on the end of the Miocene and the Pliocene within the sequences, the shift of sedimentation centers, the strong late-stage fault activities and the active natural earthquakes. The intensity, development mechanism of the neotectonics, and their controls on petroleum accumulation and distribution are quite different in different basins. Some case studies from the Bozhong depression in the Bohai Bay basin, the Yinggehai basin in the South China Sea, and the Xihu depression in the East China Sea basin indicate that the neotectonics plays an important role on late petroleum accumulation in the offshore Chinese basins.