志留系泥页岩滑脱层对大巴山前陆冲断带构造样式的影响——基于物理模拟研究  

Influence of Silurian Shale Detachment on the Structural Style of the Dabashan Foreland Thrust Belt--Based on Physical Simulation

作　　者：张晓玉 李江海[1,2] 王利杰 柳晨 胡懿灵 ZHANG Xiaoyu;LI Jianghai;WANG Lijie;LIU Chen;HU Yiling(School of Earth and Space Sciences,Peking University,Beijing 100871,China;Institute of Oil and Gas,Peking University,Beijing 100871,China;Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Natural Resources,Chengdu University of Technology,Chengdu 610059,Sichuan,China)

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]北京大学石油与天然气研究中心,北京100871 [3]自然资源部构造成矿成藏重点实验室(成都理工大学),四川成都610059

出　　处：《大地构造与成矿学》2024年第4期698-708,共11页Geotectonica et Metallogenia

基　　金：国家科技重大专项项目(2016ZX05033002-007)资助。

摘　　要：大巴山前陆冲断带处于秦岭造山带与四川盆地的过渡区,是四川盆地大中型油气藏探明储量的主要分布区,也是盆山耦合研究的典型区。该地区发育三套主要滑脱层,前人研究多以底层寒武系泥页岩和顶层上三叠统膏盐岩作为区域主控滑脱层,认为中间层志留系滑脱层使褶皱冲断带的构造样式复杂化,但是中间滑脱层对大巴山前陆冲断带的具体影响研究较少。本文通过物理模拟设计两组实验、四个模型,探讨了相同厚度的硅胶和玻璃微珠作为基底滑脱层时,中间滑脱层对于模型整体构造样式的影响,分析了其与基底及沉积盖层的相互作用。实验结果显示:①硅胶作基底滑脱层时,正向逆冲断层和反向逆冲断层数量相当,反冲断层多为自基底逆冲的断层。玻璃微珠作为基底滑脱层时,存在中间滑脱层的体系以正向逆冲断层为主,反冲断层多为浅部小型断层;②中间滑脱层的引入降低了整个体系的强度,使体系中构造变形更加复杂,模型中出现脱耦现象。中间滑脱层对前陆方向的变形起主导作用,促进了模型远端前陆方向的传播,垂向上沉积载荷的增大激活了中间滑脱层对挤压端构造样式的影响;③模拟表明,该地区志留系滑脱层使剖面出现脱耦,寒武系基底滑脱层为摩擦滑脱层,上三叠统之上发育较薄沉积盖层。The Dabashan foreland thrust belt is located in the transition zone between the Qinling orogenic belt and the Sichuan Basin.It is not only the main distribution area of proven reserves of large-and medium-sized oil and gas reservoirs in the Sichuan Basin but also a typical area for studying of basin-mountain coupling.There are three main detachments in this area:the Cambrian shale,the Silurian shale,and the Upper Triassic gypsum salt rock.Previous studies have mostly considered the Cambrian shale and Upper Triassic gypsum salt rock as the main control detachment.It is considered that the Silurian detachment complicates the structural style of the fold thrust belt,but research on the specific impact of intermediate detachment on the Dabashan foreland thrust belt is rare.In this paper,two groups of experiments and four models were designed by physical simulation.The influence of intermediate detachments on the overall structural style of the model when the base detachments comprised of silicone polymers and glass microbeads of same thickness were discussed,and the interaction between intermediate detachment and the base and sedimentary cover was further analyzed.The experimental results showed that:(1)In the system with silicone polymers as the basement detachment,the number of forward and reverse thrust faults was similar,and most of the thrust faults originated from the basement.When glass microbeads were used as the basement detachment within a system of intermediate detachment,the fault system was dominated by forward thrust faults,and most of the thrust faults were small faults from the shallow part of the model.(2)The introduction of intermediate detachment reduced the strength of the whole system,made the structural deformation in the system more complex,and decoupling occurred in the model.The intermediate detachment played a leading role in the deformation in the foreland direction and promoted the propagation in the foreland direction.An increase in the vertical sedimentary load activated the influence of

关 键 词：大巴山前陆冲断带 构造样式 中间滑脱层 志留系 物理模拟 

分 类 号：P542[天文地球—构造地质学] P628[天文地球—地质学]