青海治多县多彩地区巴塘群英安岩锆石U-Pb年代学及其地质意义  

Zircon U-Pb Geochronology and Geological Implications of the Batang Group Dacite in the Duocai Area,Zhiduo,Qinghai Province

作　　者：王凤林 魏俊浩[2] 张玉洁 徐佳富 谭俊[2] 赵少卿[3] 郑宗学 张飞[2] 刘颜[2] 

机构地区：[1]青海有色地质矿产勘查局地质矿产勘查院,西宁810007 [2]中国地质大学(武汉)资源学院,武汉430074 [3]长江大学地球科学学院,武汉430100

出　　处：《地质科技情报》2017年第1期26-32,共7页Geological Science and Technology Information

基　　金：中国地质调查局项目"青海省多彩地区铜多金属矿整装勘查区关键基础地质研究"(科[2014]04-025-081)

摘　　要：多彩地区位于甘孜-理塘缝合带的北西缘,区内与甘孜-理塘缝合带演化有关的镁铁质岩、中酸性火山岩、中酸性侵入岩等岩浆岩出露较好。选取区内相关中酸性火山岩—巴塘群英安岩为研究对象,对其进行了LA-ICP-MS锆石U-Pb同位素测试,以探讨其构造背景及成岩年代学意义。测试结果表明,巴塘群英安岩的锆石U-Pb年龄为(220±1)Ma,喷出时限为晚三叠世。结合区内已有研究成果分析,得出:1巴塘群火山岩的形成表明多彩地区处于甘孜-理塘古特提斯洋向羌塘地块南西向俯冲的陆缘弧构造背景,甘孜-理塘古特提斯洋在晚三叠世时期可能仍处于俯冲消减阶段;2多彩地区与甘孜-理塘缝合带演化有关的镁铁质岩、中酸性侵入岩、中酸性火山岩的时代表现为逐渐变新的趋势。Duocai area is located in the northwest of Ganzi-Litang suture belt,Qinhai Province.Ohiolitic mafic rocks,intermediate-acidic volcanic and intrusive rocks are widely distributed in the area.In this paper,we present LA-ICP-MS zircon U-Pb dating of dacite in the Batang Group and further discuss its geological implications.The result shows that the dacite has a crystalline age of（220±1）Ma and constrains its eruption time of the Late Triassic.Combined with previously published data,we propose that the tectonic regime of the Duocai area belongs to continental marginal arc setting during southwestward subduction of the Ganzi-Litang Paleo Tethys Ocean.The Ganzi-Litang Ocean was not closed till the Late Mesozoic.In addition,Ohiolitic mafic rocks intermediate-acidic volcanic and intrusive rocks show a gradual change from old to young.

关 键 词：锆石U-PB年代学 甘孜-理塘缝合带 英安岩 多彩地区 青海 

分 类 号：P588.12[天文地球—岩石学]