新疆科克森套地区晚古生代片麻岩化英云闪长岩的成因——锆石U-Pb年代学及地球化学证据  

The Genesis of Late Paleozoic Gneissized Tonalite in Kekesentao Area,Xinjiang:Zircon U-Pb Chronology and Geochemical Evidence

作　　者：滕宇翔 靳刘圆 薛晓峰 朱志新 Teng Yuxiang;Jin Liuyuan;Xue Xiaofeng;Zhu Zhixin(Xinjiang Geological Survey Institute,Urumqi,Xinjiang,830000,China)

机构地区：[1]新疆地质调查院,新疆乌鲁木齐830000

出　　处：《新疆地质》2022年第3期324-330,共7页Xinjiang Geology

基　　金：新疆地勘基金项目吉木乃县恰勒什海一带1:5万四幅区调(A16-1-LQ07);天山-阿尔泰增生造山带深部矿产潜力评价及编图(2018YFC0604001-04);新疆维吾尔自治区系列地质图件数据处理与洋板块地质研究(D1913)项目联合资助。

摘　　要：新疆西准噶尔北部科克森套蛇绿混杂岩由辉长岩、辉橄岩、橄辉岩、辉石岩、蛇纹岩、玄武岩、硅质岩、含放射虫硅质板岩及基质组成。在蛇绿岩带北侧形成了与构造线相一致就位的片麻岩化英云闪长岩,片麻岩化英云闪长岩主量元素均具富Al_(2)O_(3),TFeO,贫TiO_(2),MgO,CaO及全碱,贫MnO,P_(2)O_(5)特征。微量元素显示富集大离子亲石元素Rb,Ba,Th及高场强元素Zr,Hf,明显亏损Nb,Ta,Ti等元素,与岛弧玄武岩特征一致。英云闪长岩LA-ICP-MS锆石U-Pb测年获得锆石年龄(361±2)Ma,代表岩体就位年代。从构造环境上来说,片麻岩化英云闪长岩形成于晚泥盆世,具岛弧特征,岩体就位于俯冲环境下。从时间、空间分布及构造环境进行分析,科克森套蛇绿岩的形成可能早于晚泥盆世。The kekesen suite ophiolite melange in the north of western Junggar,Xinjiang is composed of gabbro,pyroxene,olivine,pyroxenite,serpentine,basalt,siliceous rock,radiolarian bearing siliceous slate and matrix.In the north side of the ophiolite belt,gneiss tonalite is formed in the same position as the tectonic line.This paper studies the gneiss tonalite.The major elements of gneiss tonalite are rich in Al_(2)O_(3) and tfeo,poor in TiO_(2),MgO,Cao and total alkali,especially poor in MnO and P_(2)O_(5).Trace elements show enrichment of large ion lithophile elements Rb,Ba,th and high field strength elements Zr,HF,and obvious loss of Nb,Ta,Ti and other elements,which is consistent with the characteristics of island arc basalt.The zircon age obtained from LA-ICP-MS zircon U-Pb dating of tonalite is(361±2)Ma,which represents the emplacement age of the rock mass.In terms of tectonic environment,the gneissized tonalite was formed in the late Devonian,with island arc characteristics,and the rock body was located in the subduction environment.In terms of time,spatial distribution and tectonic environment,the formation of the kirksen suite ophiolite may be earlier than the late Devonian.

关 键 词：科克森套 晚古生代 英云闪长岩 锆石U-PB年代学 地球化学 

分 类 号：P534.4[天文地球—古生物学与地层学] P597.3[天文地球—地质学]