西准噶尔夏尔莆岩体岩浆混合的锆石U-Pb年代学证据  

Evidence of zircon U-Pb geochronology for magma mixing of Xiaerpu granite in West Junggar

作　　者：李永军[1] 李甘雨[1] 康磊[2] 何小刚[3] 张洪伟[3] 王军年[3] 

机构地区：[1]长安大学地球科学与资源学院,西部矿产资源与地质工程教育部重点实验室,西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,中国地质调查局西安地质调查中心,西安710054 [3]新疆维吾尔自治区地质矿产勘查开发局第七地质大队,乌苏833000

出　　处：《岩石学报》2013年第9期3023-3030,共8页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41273033;41202044;40534020);陕西省自然科学基金项目(2012JM5004);新疆维吾尔自治区地质矿产调查项目(XJZBKD2006-3)联合资助

摘　　要：尽管岩相学标志是识别岩浆混合的最直接、最重要的证据,但其寄主岩石、幔源包体及基性岩墙群的精确同位素定年则是对岩浆混合证据的重要补充。夏尔莆岩体由寄主岩石、微细粒镁铁质包体和中基性岩墙群组成,高精度LA-ICP-MS锆石U-Pb测年表明三者的年龄分别为297.6±2.5Ma、298.2±8.0Ma、298.9±5.0Ma,在误差范围内一致,说明三者是同一岩浆事件的产物,为夏尔莆岩体岩浆混合成因提供了年代学证据。夏尔莆岩体的岩浆混合成因的确立证实了早二叠世西准噶尔地壳深部发生过强烈的壳幔岩浆混合作用,并导致了该地区一次重要的地壳垂向生长事件,而岩体中大量的微细粒镁铁质包体和中基性墙群正是这次生长事件的物质记录者。Although petrographical is the most direct and the most important evidence of identifying magma mixing, but the accurate isotopic ages of the host rock, enclave from mantle source, and basic dyke swarm are vital complementarity. Xiaerpu granite are composed of the host rock, marie microgranular enclave, and basic dyke swarm, LA-ICP-MS zircon U-Pb dating of the three indicates that the weighted mean 2~6pb/238U age of them are 297. 6 ~ 2. 5Ma, 298.2 ~ 8. 0Ma, 298.9 ~ 5.0Ma, that is same in error range, which show their formed in the same magma intrusion event, providing chronological proof for magma mixing of Xiaerpu granite. The establishment of magma mixing of Xiaerpu granite proving that crust depth of West Junggar has had the intense magma mixing action in Early Permian, standing for a important events of growth of the continental crust in West Junggar, and Xiaerpu granite＇ s mafic mierogranular enclave and basic dyke swarm are the matter recorder of this growth event.

关 键 词：LA-ICP-MS锆石U-PB年龄 岩浆混合 微细粒镁铁质包体 中基性岩墙群 夏尔莆岩体 西准噶尔 

分 类 号：P588.115[天文地球—岩石学] P597.3[天文地球—地质学]