三峡库区黄陵背斜形成机理及与滑坡群关系

黄陵背斜、秭归向斜是三峡地区构造地质研究热点之一,前人将其划归于秦岭造山带的组成部分,认为是东西向构造后期改造的结果;分布于此区的仙女山断裂是否穿越长江也是争论的焦点问题之一.这些问题的解决对澄清研究区地质灾害分布特征具有重要意义.笔者在前人研究的基础上,从沉积学、构造地质学角度,在大量野外地质研究工作的基础上,提出了新的看法:黄陵背斜、秭归向斜、当阳向斜、仙女山断裂同属统一的构造体系,其形成和演化与中国东西部构造格局的变迁一致,黄陵背斜具有断层相关褶皱的特点,秭归向斜具有前陆挠曲型盆地构造属性;仙女山断裂形成之初具有传递断层的属性,后期又经历了引张、挤压演化过程,不存在跨越长江向北延伸的问题;受秭归向斜沉降幅度以及东西向构造与南北向构造复合影响,在研究区形成3个滑坡聚集区,分别为贾家店滑坡聚集区、八字门向家店滑坡聚集区、兴山县城附近滑坡聚集区.

Relation of Huangling Anticline and Landslide Group in the Three Gorges Reservoir Area

The study to Huangling anticline-Zigui syncline in the Three Gorges area is hot in the field of structure geology.Predecessors thought that it was the result of a later reformation of the east-west structure,and classified it into Qinling orogenic belt.Another focus is whether Xiannü Mountain fault is across Yangtze River or not.To Solve these problems is of great importance for disclose the distribution of the geological disasters in the study area.The authors put forward a new opinion from sedimentology and tectonics based on the predecessors’studies and a lot of field work by the authors. Huangling anticline,Zigui syncline,Dangyang syncline,and Xiannü Mountain fault belong to one unified tectonic system.This is consistent with the formation and evolution of the fracture of the East-West China.Huangling anticline is the characteristics of fracture related fold,Zigui syncline has a foreland flexural basin syncline tectonic attribute,and XiannüMountain fault is the characteristics of the transfer fault with undergoing tension at first and compression later,and not going across Yangze River. Impacted by the east-west and south-north structures as well as Zigui syncline’s subsidence range,the landslide accumulation areas are formed such as Jiajiadian landslide accumulation area, Bazimen Xiangjadian landslide accumulation area,and Xingshan landslide accumulation area.