弧形构造带构造特征及其数值模拟分析——以红河断裂中南段为例  

Tectonic characteristics and numerical simulation analysis of an arcuate structural belt:A case study of the middle and southern segments of the Red River fault

作　　者：王晨旭 李西 WANG Chenxu;LI Xi(Department of Geophysics,Yunnan University,Kunming 650091,Yunnan,China)

机构地区：[1]云南大学地球物理系,云南昆明650091

出　　处：《地质力学学报》2025年第1期39-60,共22页Journal of Geomechanics

基　　金：国家自然科学基金项目(42262028)。

摘　　要：以红河断裂中南段为主体的滇东南弧形构造带作为川滇地块的西南边界和向南南东滑移的前端,现今的运动性质是以挤压为主的逆走滑运动还是以拉张为主的正走滑运动仍存在争议,这与青藏高原东南缘周围复杂的应力-应变模式有着强烈的关联。为进一步研究滇东南弧形构造带的运动学特征及成因,结合野外地质调查及已有研究成果,建立三维地质模型进行有限差分数值模拟,研究结果表明:红河断裂中南段沿线大量地质剖面显示正走滑运动性质,揭示出现今该区域主要受拉张-剪切应力作用的控制;青藏高原东南缘现今的构造变形及地貌演化主要受控于岩石圈物质的东南向移动以及苏门答腊-爪哇俯冲带下发生的弧后拉张、板块回撤2个不同力源的共同作用,同时,下地壳流的存在会显著影响青藏高原东南缘的构造变形尺度,在滇东南弧形构造带中,弧后拉张及板块回撤起着更为显著的控制作用;滇东南弧形构造带早期初始弯曲形态的形成主要归因于岩石圈物质东南向移动的影响及小江断裂左旋走滑的牵引,并在先存构造几何形态的限制和弧后拉张及板块回撤的控制下产生持续形变。研究结果有助于理解滇东南弧形构造带现今的活动特征及成因,并为青藏高原东南缘构造演化研究提供定量化分析的参考和理论依据。[Objective]The southeast Yunnan Arcuate Structural Belt,with the central and southern segments of the Red River fault as its main body,serves as the southwestern boundary of the Sichuan-Yunnan block and the forefront of its south-southeastward movement.However,there is still controversy as to whether its current motion is primarily characterized by transpression or transtension.This debate is strongly correlated with the complex stress-strain patterns surrounding the southeastern margin of the Qinghai-Tibet Plateau.Clarification of the kinematic characteristics and genesis of the southeast Yunnan Arcuate Structural Belt will help to understand the regional tectonic evolution.[Methods]This study utilized the interpretation of remote sensing images and geological field surveys to identify evidence for late Quaternary tectonic activity in the central and southern segments of the Red River fault.A three-dimensional(3D)geological model tailored to the actual characteristics of the region was established.It considers the influence of lower crustal flow and includes finite-difference numerical simulations with different velocity boundary conditions set at 26.5°N.[Results]The study reveals:(1)Numerous geomorphic features and fault profiles in the central and southern segments of the Red River fault indicate that most of the faults along the line are predominantly high-angle,northwest-striking with a complex fault rock development.The presence of structural wedges and infill of overlying material has been observed in several typical outcrops.Additionally,there are significant undulations in the lower part of the overlying strata on both sides of the fault.(2)The numerical simulations show that the influence of the far-field stress on the horizontal and vertical deformation of the southeastern margin of the Qinghai-Tibet Plateau is quite different on both sides of 26.5°N,and the deformation is further enhanced by the presence of lower crustal flow.(3)Numerical simulations of velocity fields,maximum shear strain rates,and

关 键 词：青藏高原东南缘 滇东南弧形构造带 红河断裂 三维地质模型 有限差分数值模拟 构造变形 

分 类 号：P54[天文地球—构造地质学] P313[天文地球—地质学]