西准噶尔达尔布特蛇绿岩带萨尔托海岩体深部结构、构造特征:地质与地球物理证据  

Deep Structure and Texture of the Sartohay Ophiolite in West Junggar,Xinjiang:New Geological and Geophysical Evidence

作　　者：李海 李永军[1,2] 徐学义[1,3] 万阈 赵强 杨高学 王祚鹏[1] LI Hai;LI Yongjun;XU Xueyi;WAN Yu;ZHAO Qiang;YANG Gaoxue;WANG Zuopeng(School of Earth Science and Resources,Chang'an University,Xi'an 710054,Shaanxi,China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MLR,Xi'an 710054,Shaanxi,China;China Aero Geophysical Survey&Remote Sensing Center for Land and Resources,Beijing 100083,China;Seventh Geological Survey Team,Xinjiang Bureau of Geology and Mineral Resource Exploration,Wusu 833000,Xinjiang,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,陕西西安710054 [3]中国自然资源航空物探遥感中心,北京100083 [4]新疆地矿局第七地质大队,新疆乌苏833000

出　　处：《大地构造与成矿学》2021年第4期634-650,共17页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41273033);国家重点研发计划专项子课题“天山-阿尔泰大宗矿产分布规律研究与深部资源潜力评价”(2018YFC0604001);中央高校专项基金(300102279209)联合资助。

摘　　要：西准噶尔地区分布多条蛇绿混杂岩带,地表地质已有大量研究成果,但蛇绿岩深部结构构造研究相对薄弱,一定程度上制约了该地区地质构造演化的深入认识。为此,本文选取达尔布特蛇绿混杂岩带萨尔托海段开展了大比例尺地质填图配套地面重力、磁法和可控源音频大地电磁测深(CSAMT)等综合测量,获得了该蛇绿岩体地表分布、接触关系以及深部的磁性、密度结构和电性特征,精细刻画了蛇绿岩的深部结构与构造,并进一步分析了其侵位机制和动力学过程。萨尔托海蛇绿岩具有低重力、高磁性和变化范围较宽的电阻率值,岩体整体以构造岩块状产出,表现出挤压逆冲、走滑剪切、破碎蚀变等变形变质。本文及前人研究成果表明,萨尔托海岩体是在近东西向挤压兼走滑应力作用下以斜向楔冲形式构造就位,并进一步受到后期左行走滑和岩浆作用的叠加改造。结合区域构造演化,西准噶尔蛇绿岩的构造侵位与晚石炭世板块汇聚背景下残余洋盆的收缩有关,持续的挤压兼走滑应力使残余洋盆下伏基底蛇绿岩沿断裂构造侵位于上覆沉积地层。The West Junggar located in the southwest margin of the Central Asia Orogenic Belt(CAOB)has several Paleozoic ophiolitic mélanges.These ophiolitic mélanges record the Paleo-Asian Ocean evolution which are critical for the understanding of the components,tectonic evolution and crust-mantle interaction of the CAOB.Surface researches have achieved lots of results,however,the deep structure of the ophiolitic mélanges is still unclear.Previous researches are mainly based on geological mapping and structural analysis,however,lack constraints on deep information.Based on detailed geological survey of the Darbut ophiolitic mélange in the Sartohay area,comprehensive geophysical measurements including ground gravity,magnetic and controlled-source audio-frequency magnetotelluric(CSAMT)measurements were conducted.The surface distribution,contact relationship and gravity,magnetic,CSAMT data of the Sartohay ophiolite were recorded.Constrained by surface geology and drilling information,the obtained geophysical data were inverted and interpreted,and the deep structure and texture of the Sartohay ophiolite were interpreted.The comprehensive analysis of geology and geophysics shows that the Sartohay ophiolite consists of rootless tectonic blocks which are characterized by oblique thrust,transverse extrusion and lateral strike slip.Controlled by W-E compressive stress with strike-slip component,the ophiolites were emplaced in the form of oblique wedge-thrusting,and further reformed by sinistral strike-slip and magmatism in the later stage,Their emplacement is closely linked to the shrinkage of remnant ocean basin,whereas the convergence of the Kazakhstan and the Junggar terranes in Late Carboniferous is the important background of this dynamic process.

关 键 词：蛇绿混杂岩 深部结构与构造 地球物理 萨尔托海岩体 西准噶尔 

分 类 号：P54[天文地球—构造地质学]