摘要
滑坡等地质灾害往往受控于区域构造.狗磨湾滑坡隶属南秦岭印支褶皱系安康逆冲推覆构造带内庙岭村—长沙河区域韧性剪切带之中.该剪切带经历了多期活动,后期演化为脆性断层.对该韧性剪切带的研究是了解滑坡形成机理的有效手段.通过对韧性剪切带的显微构造、石英c轴组构及后期脆性构造的应力等变形特征进行研究.结果显示:①庙岭村—长沙河区域韧性剪切带表现为早期左行,晚期右行,断层均经历了压扭⁃张性的多期次活动特征;②韧性剪切带以构造片岩和千糜岩为主,发育大量云母类片状矿物,大大降低了岩石强度;③早⁃中期共轭节理σ1倾伏向多变,倾伏角一般较小.与正断层同时生成的晚期无任何充填物节理和在第四系黄土中晚期节理σ1虽然倾伏向变化较大,但倾伏角一般大于70°,指示了现今区域应力机制主体以伸展为主,且这些节理与目前仍在活动的活断层密切相关.基于上述研究结果,认为韧性剪切带及其进一步演化形成的断裂构造对狗磨湾滑坡的形成和发展具有重要的控制作用.
Geological disasters such as landslides are often controlled by regional structures.The Goumowan landslide belongs to the ductile shear of Miaolingcun⁃Changshahe region in Ankang thrust⁃nappe structural belt of the Indosinian fold system of the South Qinling Mountains.The shear belt experienced multiple periods of activity and evolved into a brittle fault in the later stage.The study of the ductile shear belt is an effective means to un⁃derstand the formation mechanism of landslide and prevent the occurrence of landslide.In this paper,the micro⁃structure of ductile shear belt,the quartz C axis fabric and the stress of the brittle structure in the later period are studied.The results show that:(1)The ductile shear belt in Miaolingcun⁃Changshahe region is in the early left row and in the late right row,and the faults all experience the characteristics of multi⁃stage activity of compres⁃sion,torsion and tension;(2)The ductile shear belt is mainly composed of structural schist and chyme,and a large number of mica⁃like flake minerals are developed,which reduces the rock strength;(3)Early⁃middle conjugated jointσ1 has variable dip direction and generally small dip Angle.In the late period of quaternary loess there were no filling joints generated at the same time with normal faults,and in the late period of quaternary lo⁃ess there were no filling joints.Although the dip direction varied greatly ofσ1,the dip Angle was generally grea⁃ter than 70°,indicating that the main body of the regional stress mechanism was mainly extensional,and these joints were closely related to active faults.Based on the above research results,it is considered that the ductile shear belt and the faulted structure formed by its further evolution play an important role in controlling the forma⁃tion and development of the Goumowan landslide.
作者
李小兵
魏刚锋
李建飞
LI Xiaobing;WEI Gangfeng;LI Jianfei(College of Geographical Sciences,Shanxi Normal University,Taiyuan 030031,Shanxi,China;MOE Key Laboratory of Western China̓s Mineral Resources and Geological Engineering,MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,Faculty of Earth Science and Resources,Chang̓an University,Xi̓an 710054,Shaanxi,China)
出处
《山西师范大学学报（自然科学版）》
2022年第1期96-105,共10页
Journal of Shanxi Normal University(Natural Science Edition)
基金
科技基础资源调查专项(2017FY100905).
关键词
韧性剪切带
脆性断层
显微构造
节理
狗磨湾滑坡
Ductile shear belt
Brittle fault
Microstructure
Joint
Goumowan landslide
