伊宁地块阿腾套山塔勒德萨依岩体:高分异花岗岩成因分析  

The Taledesayi Granite Pluton in the Atengtao Mountains of the Yining Block:Genesis Analyses of A Highly Fractionated Granite

作　　者：罗耀清 李永军[1,2] 林广春 王祚鹏[1] 任朋飞 滕明耀 LUO Yao-qing;LI Yong-jun;LIN Guang-chun;WANG Zuo-peng;REN Peng-fei;TENG Ming-yao(School of Earth Science and Resources,Chang’an University,Xi’an 710054,China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MLR,Xi’an 710054,China)

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]自然资源部岩浆作用成矿与找矿重点实验室,西安710054

出　　处：《矿物岩石地球化学通报》2019年第6期1191-1206,共16页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41273033);中国地质调查局区域地质调查项目(T16-1-LQ02)。

摘　　要：为探讨阿腾套山西南缘塔勒德萨依正长花岗岩-花岗斑岩体的形成时代和岩石成因,为伊宁地块石炭纪构造演化提供可靠资料,对塔勒德萨依岩体进行了野外调查、锆石U-Pb定年及地球化学研究。结果显示,花岗斑岩年龄为(338±3)Ma,表明岩体形成于密西西比亚纪。花岗岩的矿物组成接近低共结组分,全岩以高Si、富碱、富K和Rb,低Ti、少Fe、Ca、Mg,贫Ba、Sr、P等为特征,表明其为高分异花岗岩类。结合区域同时代(362~325 Ma)岩浆岩的地球化学资料,认为该花岗岩的母岩浆由混合地壳(新生地壳和元古代角闪岩相基底)部分熔融形成且母岩浆历经了斜长石、角闪石、黑云母、磷灰石和锆石等矿物的分离结晶。综合区域资料认为,塔勒德萨依岩体形成于弧后盆地,此类高分异花岗岩的形成可能标志着维宪期(338 Ma)南天山洋已进入衰亡期。In order to explore age and petrogenesis of the Taledesayi syengranite-porphyry pluton in the southwestern Atengtao Mountains and to provide reliable information for the tectonic evolution of the Yining Block in Carboniferous,we have carried out field geological survey,zircon U-Pb dating,and geochemical research of the Taledesayi pluton in this paper.The LA-ICP-MS zircon U-Pb age of granite porphyry of(338±3)Ma indicates that the pluton was formed in the Carboniferous Mississippian period.Mineral compositions of the granite are close to the minimum eutectic composition.Its’chemical compositions are characterized with high contents of Si,K and Rb,alkaline-rich,but low contents of Ti,Fe,Ca,Mg,Ba,Sr and P,indicating it is highly fractionated granite.Based on the analysis of geochemical data of contemporary(362-325 Ma)magmatic rocks,we believed that parental magma of the granite could be derived from partial melting of the mixed crust(juvenile crust+Proterozoic basement of amphibolite facies)and then underwent the fractional crystallization of plagioclase,hornblende,biotite,apatite,zircon and other accessory minerals.With the combination of the regional geological data,we have concluded that the Taledesayi granite was formed in the back-arc basin.The occurrence of the highly differentiated granitic pluton may indicate that the Southern Tianshan Ocean was coming to an end in Visean age(338 Ma)of Carboniferous Mississippian period.

关 键 词：高分异花岗岩 密西西比亚纪 塔勒德萨依岩体 阿腾套山 伊宁地块 

分 类 号：P588.121[天文地球—岩石学]