湖北巴东地区滑脱构造与地震活动特征

通过对川东-鄂西地区弧形薄皮构造以及岩石力学性质的研究认为，本区存在中三叠统巴东组、下三叠统大冶组、下二叠统栖霞组、下志留统罗惹坪组4个易于发生构造滑脱的软弱地层。结合三峡地区地球物理探测结果，构建了巴东地区多层滑脱构造的理论模型。结果显示，该区地震活动的空间分布与滑脱构造的几何形态非常一致，地震活动多沿着区内3条NE向滑脱背斜的枢纽方向分布，背斜核部地震较少，而两翼地震较多，且较大地震多发生在两翼较深处。多层滑脱构造组成的构造背景、碳酸盐岩的大面积分布以及库水位的反复加卸载是造成巴东地区地震特征复杂性的3个主要因素。

Decollement Structures and Seismic Activity of Badong Area in Hubei Province

Through review of thin crust structure studies in east Sichuan and western Hubei area, along with experimental results of rock mechanics in recent years, this article suggests that there exist four soft layers to form slippage system, including the Triassic Badong group, the lower Triassic Daye group, the lower Permian Qixia group, and lower Silurian Luoreping group. Combined with geophysical detection results of the Three Gorges region, we build a theory model of multilayer decollement in the Badong area.We find that the spatial distribution of seismic activity in this area aligns with the decollement geometry very well, that seismic activity is distributed along the direction of the 3 NE stripping joints in the area and less in the core of the anticline, that earthquakes occurring in the anticline core are less than in the two wings, and larger earthquakes tend to occur in the depths of the two wings. Finally, we believe that the decollement, limestone areas, and the fluctuation of water level are three essential factors of seismic activity complexity in Badong area.