多滑脱层对大巴山前陆褶皱冲断带构造变形的控制:基于离散元数值模拟研究  

The control of multiple detachment layers on structural deformation of Dabashan foreland fold-thrust belt:Constraint from discrete element numerical simulation

作　　者：张晓玉 李江海[1,2] 豆方鹏 徐海轩 柳晨 ZHANG Xiaoyu;LI Jianghai;DOU Fangpeng;XU Haixuan;LIU Chen(School of Earth and Space Sciences,Peking University,Beijing 100871,China;Institute of Oil and Gas,Peking University,Beijing 100871,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

出　　处：《地质学报》2025年第3期733-743,共11页Acta Geologica Sinica

基　　金：国家重点研发计划课题(编号2023YFC2906501)资助的成果。

摘　　要：大巴山前陆褶皱冲断带处于秦岭造山带和四川盆地间的过渡位置,是现今四川盆地大中型油气藏探明储量的重要分布区域。研究区位于四川盆地东北部大巴山构造带,区内发育多套滑脱层,滑脱层的分布控制了研究区的构造变形。前人依据地质露头分析和三维地震解释等技术方法厘定了研究区的主要构造样式,但对于构造变形过程及运动学特征尚缺乏定量化分析。本文采用离散元数值模拟方法,通过PFC2D软件计算相同时间步长内显示的构造样式的差异,设计了单滑脱层体系、双滑脱层体系和多滑脱层体系三个模型进行离散元单因素对比模拟实验,探讨各滑脱层体系中构造样式的差异。实验表明:①滑脱层对于剖面中构造的发育具有控制作用。一方面,从断层的发育数量来看,双滑脱层体系与多滑脱层体系中断层的发育数量均多于单滑脱层体系,滑脱层的引入使得体系中的构造发育更加复杂;另一方面,从发育的断层性质分析可知,随着滑脱层数量的增加,体系中前冲断层数量呈递增趋势,反冲断层的数量在多滑脱层体系中表现为少于前两个模型,且明显少于双滑脱层体系中反冲断层的数量,中间滑脱层对于形成反冲断层具有抑制作用。②滑脱层的引入加快了断层在垂向上的逆冲速度,中间滑脱层起到了联结基底滑脱层和上部滑脱层的作用。双滑脱层体系中普遍存在构造解耦现象,多滑脱层体系中以发育次级断层和次级褶皱为主要特征。③多滑脱层体系表现了明显的次级褶皱及次级断层特征,与大巴山东段剖面较为贴合,双滑脱层体系表现为具有较多构造解耦特征,与西段剖面较为贴合。The Dabashan foreland fold-thrust belt,located in the transitional position between the Qinling orogenic belt and the Sichuan basin,is an important distribution area for the proven reserves of large and medium-sized oil and gas reservoirs in the Sichuan basin.The research area is located in the Dabashan tectonic belt in the northeastern part of the Sichuan basin,which is characterized by the presence of multiple detachment layers.The distribution of these detachment layers plays a significant role in controlling the structural deformation of the research area.Previous studies have determined the main structural styles of the study area based on geological outcrop data,3D seismic data,and other technical methods.However,there is still a lack of quantitative analysis of the structural deformation process and kinematic characteristics.To address this gap,our study uses the discrete element numerical simulation method to calculate the differences in structural styles displayed within the same time step using PFC2D software.Three models,namely the single detachment layer system,the dual detachment layer system,and the multiple detachment layer system,were designed for discrete element single factor comparative simulation experiments to explore the differences in structural styles among each detachment layer system.Our experimental results demonstrate the following findings:①the detachment layer plays a controlling role in the development of structures in the cross section.The dual detachment layer system and the multi detachment layer system exhibit a higher number of faults compared to the single detachment layer system.The introduction of detachment layers adds complexity to the structural development.Additionally,the analysis of the developed fault properties reveals that with an increase in the number of detachment layers,the number of forward thrust faults gradually rises.The number of reverse thrust faults in the multi detachment layer system is less than the first two models and is significantly less than the

关 键 词：大巴山前陆褶皱冲断带 构造变形 滑脱层 离散元数值模拟 

分 类 号：R68[医药卫生—骨科学]