黄、渤海活动断裂初探

PRELIMINARY DISCUSSIONS ON ACTIVE FAULTS IN THE YELLOW AND BOHAI SEAS

本文初步讨论了区内活动断裂的时空展布及一般特征,NNE—NE向继承性活动断裂是渤海海域及沿海大陆的主导构造,北黄海断裂活动与渤海相似,南黄海则以NEE向为主,苏北陆地及其近海兼有NNE—NE和NW向。资料表明,断裂的水平运动量大于垂直运动量,从各自的沉积厚度所估算的沉积速率说明早、晚第三纪和第四纪的构造强度是很近似的,因而华北和渤海区由走滑正断层反映的水平运动和差异升降运动仍处于十分活跃的发展阶段。

Based on marine seismic profile interpretation and some continental-oceanic data, time-space distribution and general features of active faults in the Yellow and Bohai Seas and in the neighbouring area have been studied. Inherited NE active fault makes up dominant structure in the Bohai Sea and in its coast land.The North Yellow Sea has a similarity to the Bohai Sea, but active fault in the South Yellow Sea is dominated by NEE in direction, and even by NE and NW in northern Jiangsu land and in the offshore area. The available data have showed that horizontal movement of the faulting is larger than vertical one, and sedimentation rates, estimated according to sedi-ment thickness of Eogene, Neogene and Quaternary respectively, have indicated that structural intensity is nearly the same during these three periods. Thus it can. be said that horizontal movement and differential uplift and subsidence, reflected by strike-slip normal fault, are still in a very activ development in North China and in the Bohai Sea area. There is a large dispute about time limit of the active faults. This paper takes all faults which were formed or once reactive from Neogene as active ones. Geologic hazards such as active fault in sea area, sea-floor slide, sediment mass migration and earthquake are related to each other, and they are also the major factors of sea-area stability. Therefore, to study active fault in sea and adjacent land area has practical significance both to petroleum prospecting and to prevention and control of geologic hazards.