关键词: 新构造运动, 晚期断裂, 裂后热沉降, 油气成藏

Abstract: Miocene to the present time is the most active period for the post-fault thermal subsidence in China’s offshore Tertiary basins. Accompanied with the post-fault structural activities again, the fault activities are also extremely active. Fault is the most direct and important form to reflect the new structural movements in this period. The fault activities in this stage (since 5.3Ma) are called the late-stage faults. The fault activities in China’s offshore basins in this stage are different in characteristics and distribution. The difference is even great in the same basin but the different structural units. However, the fault activities in this stage have some common characteristics no matter they take place in the basins in Bohai Sea, East China Sea or the northern part of South China Sea. They are accompanied with the sag-controlled basement faults and successive activities of regional faults belonging to the same deposit or restoration of activities. There are a large amount of faults during this stage, small-scale and arrayed in the feather shape. They are mainly distributed in the nearly eastwest and northwest-west directions. The fault-active regions and fault activities in this stage have the key effect on the oil and gas migration and accumulation in the late stages, which shaped and renovated a number of late-stage traps, formed the conducting systems for oil and gas migration, adjusted and controlled the oil and gas migration and accumulation in this region and final distribution of oil and gas fields. The study of the development and distribution characteristics of those fault activities in this stage is of great importance to guide the oil and gas exploration of these basins.