基于离散元数值模拟的雪峰山前陆褶皱冲断带齐岳山分界断裂性质与形成过程  

Tectonic Characteristics and Evolution of the Qiyueshan Fault in the Xuefengshan Foreland Fold-and-Thrust Belt:Insights from Discrete Element Numerical Simulations

作　　者：王帅杰 颜丹平[1,2] 周志成 孔霏 景含阳 廖威 WANG Shuaijie;YAN Danping;ZHOU Zhicheng;KONG Fei;JING Hanyang;LIAO Wei(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Key Laboratory of Intraplate Volcanoes and Earthquakes,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质大学(北京)陆内火山与地震教育部重点实验室,北京100083

出　　处：《现代地质》2025年第1期18-30,共13页Geoscience

基　　金：国家自然科学基金项目(42030306,41972206和42372263);深时数字地球前沿科学中心“深时数字地球”中央高校科技领军人才团队项目(2652023001)

摘　　要：NE向分布的齐岳山断裂将雪峰山前陆褶皱冲断带划分为西北部的川东隔挡式褶皱冲断带和东南部的湘西隔槽式褶皱冲断带。然而,齐岳山断裂的性质和形成过程长期以来缺乏明确共识,导致对雪峰山前陆褶皱冲断带的形成机制和演化过程存在显著分歧。为揭示齐岳山断裂的形成机制及其对两侧构造变形差异的控制作用,本文基于地震反射剖面解释,采用离散元数值模拟方法设计5组模型进行实验研究。研究结果表明,若存在先存断裂,变形集中于其部位,影响断层生成顺序;若无先存断裂且多套滑脱层具有较低内聚力,变形主要沿下部滑脱层传递;当中间滑脱层厚度大于下部滑脱层时,变形主要受中间滑脱层控制。结合地震剖面的分析,本文认为雪峰山前陆褶皱冲断带表现为“双层台阶式断弯褶皱带”,齐岳山断裂形成于前陆褶皱冲断带的递进变形过程中,其两侧构造差异主要受基底滑脱层分布和寒武系滑脱层力学性质的主导作用。湘西隔槽式褶皱冲断带由深层断弯褶皱控制,而川东隔挡式褶皱冲断带由浅层断弯褶皱控制。The NE-trending Qiyueshan Fault divides the Xuefengshan foreland fold-and-thrust belt into the northwestern Eastern Sichuan fold-and-thrust belt and the southeastern Western Hunan fold-and-thrust belt.However,the nature and formation process of the Qiyueshan Fault remain debated,resulting in significant discrepancies in understanding the formation and evolution mechanisms of the Xuefengshan foreland fold-and-thrust belt.To investigate the formation of the Qiyueshan Fault and its control on differential deformation on both sides,seismic reflection profiles were interpreted,and five discrete element numerical simulation models were designed for experimental analysis.The results reveal that pre-existing faults localize deformation and influence the sequence of fault generation.In contrast,without pre-existing faults,deformation predominantly propagates along the lower detachment layer under weak cohesion.When the thickness of the middle detachment layer exceeds that of the lower detachment layer,deformation is governed by the middle detachment layer,leading to partial decoupling of the competent layers above and below it.Based on a comparison with seismic reflection profiles,the Xuefengshan foreland fold-and-thrust belt is characterized as a“double-step fault-bend fold system.”The Qiyueshan Fault formed during progressive deformation of the foreland belt,and the structural differences across the fault are primarily controlled by the distribution of the basal detachment layer and the mechanical properties of the Cambrian detachment layer.The Western Hunan fold-and-thrust belt is governed by deep-seated fault-bend folding,while the Eastern Sichuan fold-and-thrust belt is controlled by shallow fault-bend folding.

关 键 词：雪峰山 前陆褶皱冲断带 齐岳山断裂 离散元数值模拟 多滑脱层 

分 类 号：P542.2[天文地球—构造地质学] P631[天文地球—地质学]