【摘要】 利用在渤海最新获得的约5 000 km的浅层地震资料,发现在渤海海域发育大量晚更新世—全新世断裂和褶皱,进而对其分布、浅层结构、运动学性质和活动性进行了研究,绘制了渤海海域活动断裂分布图。研究结果表明:渤海晚更新世—全新世活动断裂主要走向为北北东向、北西向和近东西向,东西向断裂数量最多;断裂的形成受区域应力场和早期断裂的控制,而褶皱则以背斜居多,通常沿早期断裂带发育;就分布密度而言,辽东湾内断裂密度远小于其他海域,而同一构造单元其边界部位断裂密度大于单元内部;具继承性发展的断裂多具有复杂的破裂结构,破裂带剖面上呈耙形或"Y"字型,晚更新世沉积层变形明显;受断裂错动地层的形成时代表明,多数断裂的最新活动发生在晚更新世中期-晚期,部分断裂在全新世发生过活动;多数断裂具有明显正断拉张作用,而郯庐断裂带和张家口-蓬莱断裂带内次级断裂还可能具走向滑移分量;渤海浅层断裂的活动性与现代地震震中的分布具有较好的相关性,这对于渤海地震危险性评价具有重要意义。更多还原

【Abstract】 By using 5 000 km long shallow penetrated seismic data collected in recent years in the Bohai Sea,many active faults and folds were found in Late Pleistocene—Holocene unconsolidated sediments.The distribution map of active faults is plotted.Further,their distribution,shallow structures,kinematics and activities are discussed in detail.The research results show that strikes of active faults express three predominant directions: NNE,E-W and NW.The quantity of faults with an E-W-trending is the most.Fault forming is controlled by regional tectonic stress and the former faults.Most of folds are anticlines and develop along the former faults.The distribution density of active faults in the Liaodong Gulf is smaller than in other sea area.In a same structural unit,more faults developed in the boundary zone than in its inner zone.The inherited fault is usually characterized by complex fracture zone where sedimentary sequences are deformed.Fracture zones usually exhibit rake-shaped or Y-shaped on the section.The formation age of sedimentary sequences offset by faults shows that the latest tectonic movement event of most faults occurs during the middle or the end of the Late Pleistocene and parts of faults are active during the Holocene.Most of faults are dominated by the normal component,but subfaults in the Tan-Lu fault zone and the Zhangjiakou—Penglai fault zone may be with some strike-slip component besides the normal component.Activities of shallow faults in the Bohai Sea have a good correlation with the earthquake epicenter,which is valuable for seismic risk assessment.更多还原