西准噶尔达拉布特断裂带中段晚古生代构造分析  

Structural analysis of Late Paleozoic deformation of central Dalabutefault zone,West Junggar,China

作　　者：林伟[1,2] 孙萍 薛振华 张仲培[3] LIN Wei SUN Ping XUE ZhenHua ZHANG ZhongPei(State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China SINOPEC Research Institute of Petroleum Exploration and Development, Beijing 100083, China)

机构地区：[1]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029 [2]中国科学院大学地球科学学院,北京100049 [3]中国石油化工集团公司石油勘探开发研究院,北京100083

出　　处：《岩石学报》2017年第10期2987-3001,共15页Acta Petrologica Sinica

基　　金：科技部国家重点研发计划项目(2016YFC0600401;2016YFC0600102)资助

摘　　要：走滑断裂构造在中亚造山带增生及演化过程的研究中扮演了重要角色,其主要构造单元均被走滑断裂带所分割。西准噶尔造山带是中亚增生型造山带的重要组成部分,达拉布特断裂是西准噶尔造山带中一条重要的走滑断裂,其复杂的构造表现吸引了大量研究者的关注。前人不仅在其构造解释上存在着走滑断层、逆冲断层或压扭性断层等诸多争议,且在其活动时代问题上也有不同的看法。本文依据在达拉布特断裂带中段开展的详细野外构造学工作,结合前人针对该地区石炭纪火山岩、浊积岩和造山后花岗岩侵入体所做的同位素年代学工作成果,对达拉布特断裂的活动性质和活动时代进行了讨论。结果确认在中二叠统沉积之前,达拉布特断裂带存在两期变形事件,分别对应于320Ma左右沿NE-SW的较深层次的左行走滑事件D1和表现为脆-韧性转换域的轴面倾向SE的褶皱作用构造事件D2。前者为主期变形事件,而后者发生在中二叠统沉积之前。本文同时报道了沿达拉布特断裂带出露右行走滑构造形迹,并讨论了其可能的成因。沿达拉布特断裂带的多期构造事件记录了西准噶尔地区造山后大规模走滑构造调整过程,是晚古生代晚期中亚各个陆块拼合后大规模陆内调整在西准噶尔造山带的具体体现。Researches of strike-slip faults play a significant role in the research of the accretion and evolution process of the Altaids,whose main tectonic units all separated by regional strike-slip faults.Dalabute fault is an important strike-slip fault developed within the West Junggar Orogen.The fault was hotly debated on its kinematics and age.Some representative models have been proposed：strikeslip fault,thrust fault or transpressional fault,etc.We discussed the kinematics and age of the Dalabute fault in this article based on our field observation in central part of the fault,combined with research results of previous geochronological studies of the volcanic rocks,turbidites and post-collisional granite plutons.We have confirmed the existence of two-stage deformation between Late Carboniferous and Permian.The early one concerns a Late Carboniferous（~320 Ma） ductile sinistral strike-slip event which is the main deformation event,and the second one shows a folding event which presented by folds with SE-inclined axial planes developed within the ductile-brittle transitional condition,and formed before the deposition of the Permian strata.We also reported some geological structure showing dextral strike-slip,and they might be the result of folding of the early sinistral strike-slip structure,or the relics of an earlier dextral strike-slip event.The multi-stage deformation along the Dalabute fault is a record of post-orogenic extension and strike-slip tectonic adjusting in the West Junggar area,and it＇s a concrete reflection of the large scale intracontinental tectonic adjusting developed within Central Asia fromLate Carboniferous to Early Permian.

关 键 词：达拉布特断裂带 多期构造变形 左行走滑 西准噶尔晚古生代造山带 陆内调整 中亚增生型造山带 

分 类 号：P542[天文地球—构造地质学]