【摘要】 三峡地区处于扬子板块北缘,北部与秦岭造山带相连,西部和四川盆地相邻,东北及东南部分别为华北板块及华南褶皱带,其在历史上各种地质构造运动频繁、复杂.本文利用三维重力成像方法,得到了三峡地区中上地壳三维密度分布,结果显示黄陵背斜为高密度异常区域,其最深处大约15km;黄陵背斜周围的主要区域性断裂构造呈菱形分布,这些断裂深度大约10～15km,一般切割至中地壳上部,控制着该区域的构造演化过程以及大部分的地震分布;黄陵背斜中部沿长江一线有大面积低密度地层分布,推测主要为低密度物质沿雾渡河断裂侵入有关.此外,西部的秭归盆地为低密度沉积区域,其沉积厚度明显不均,自巴东向秭归方向沉积厚度明显加深.更多还原

【Abstract】 The Three Gorges located in northern margin of Yangtze plate, is surrounded by four different geotectonic units: Qinling orogenic belt in north, Sichuan basin in west, North China plate in northeast and South China fold belt in southeast. In history, there are so many kinds of tectonic movements occurred. Utilizing Bouguer gravity anomaly in the Three Gorges area, and based on the technology of 3D gravity inversion, the 3D density structure of the upper and middle crust of Three Gorges reservoir area is obtained. The results show that Huangling anticline is a high density area, with a maximum depth of about 15 km. The distribution of regional faults around the Huangling anticline is lozenge-shaped, and those faults cut to the top of the middle crust with a depth of about 10-15 km, controlling the tectonic evolution and earthquake distributions in this area. Along Yangtze River, there is a low density stratum in the middle of Huangling anticline, which presumably is the result of the low density materials intruded along Wuduhe fault. Furthermore, Zigui basin in west has low density values, and its deposit stratum is nonuniform in thickness, that is, becoming thicker and thicker from Badong to Zigui.更多还原