克拉美丽断裂带构造变形特征及其成因演化

Structural deformation characteristics and its genetic evolution of Kelameili fault zone

克拉美丽断裂带作为中亚造山带的一级盆缘断裂带,控制着准噶尔盆地东北缘的形成和演化,是解析盆-山耦合的关键要素。该断裂带因经历了多期次构造运动的叠加,构造变形错综复杂。目前对克拉美丽断裂带的形成与演化存在许多认识上的分歧,对演化过程中不同构造阶段的构造变形特征还缺少系统的研究。文中通过野外露头踏勘、实测及剖面演化分析,对克拉美丽断裂带构造变形特征、变形机制、形成演化进行了系统研究。研究认为:1)克拉美丽断裂带是一条至今仍在活动的脆-韧性右旋压扭断裂带,具有多期活动性,发育大量派生构造,其展布及力学性质符合Harding应变椭圆模式;2)克拉美丽断裂带东段分形维数值为0.966,西段分形维数值为1.109,证实了克拉美丽断裂带的东西分段特征和准噶尔盆地东北缘碰撞造山时期西强东弱的特点;3)克拉美丽断裂带开始形成于石炭纪晚期,经历了挤压—走滑—再挤压的复合应力背景,挤压主要发生在海西中晚期及喜山期,右旋走滑始于印支期,燕山期最为强烈。

As a first-order basin-margin fault zone in the Central Asian orogenic belt,the Kelameili fault zone controls the formation and evolution of the northeastern margin of Junggar Basin,and is the key factor to analyze the basin-mountain coupling.Due to the superposition of multiple tectonic movements,the structural deformation is complicated.There are many differences in understanding of the formation and evolution of the Kelameili fault zone,and there is a lack of systematic research on the structural deformation characteristics in different tectonic stages during the evolution process.Based on field outcropping survey,field measurement and profile evolution analysis,the structural deformation characteristics,deformation mechanism,formation and evolution of the Kelameili fault zone have been systematically studied.It is concluded that:(1)the Kelameili fault zone is a brittle-ductile dextral compression torsion fault zone which is still active up to now.It has multi-stage activity and a large number of derived structures are developed.Its distribution and mechanical properties accord with the Harding strain ellipse model.(2)the fractal dimension of the eastern segment of the Kelameili fault zone is 0.966,and that of the western segment is 1.109,which confirms the characteristics of the east-west segment of the Kelameili fault zone and that the west is strong and the east is weak during the collision orogeny in the northeastern margin of the Junggar Basin.(3)the Kelameili fault zone began to form in the late Carboniferous period,and experienced the composite stress background of compression,strike-slip and recompression.Compression mainly occurred in the middle and late Hercynian and Himalayan period,while dextral strike-slip started in the Indosinian period and was most intense in the Yanshanian period.