西准噶尔托里县布尔克斯台岩体岩浆混合的锆石U-Pb年代学证据  

Evidence from Zircon U-Pb Geochronology for Magma Mixing of the Buerkesitai Granite in the Tuoli County,Western Junggar,Xinjiang,China

作　　者：晁文迪 李永军[1,2] 王冉[1,2] 康磊[2,3] 

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,西安710054 [3]中国地质调查局西安地质调查中心,西安710054

出　　处：《矿物岩石地球化学通报》2016年第1期99-108,共10页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41273033;40534020;41202044);中国地质调查局项目(1212011220619);陕西省自然科学基金项目(2012JM5004);新疆两权价款中央留成专项资金项目(Y14-5-LQ06)

摘　　要：新疆西准噶尔托里县布尔克斯台岩体中发育大量闪长质微细粒包体,包体主要分布于阿达依金矿外围,具塑性变形特征。为确定岩浆混合作用存在的年代,对布尔克斯台岩体寄主岩石和包体进行LA-ICP-MS锆石U-Pb定年,得到其形成年龄值分别为313.7±2.7Ma(95%置信度,MSWD=1.8,n=21)和312.2±3.9Ma(95%置信度,MSWD=2.5,n=26),表明二者是同期岩浆事件的产物。布尔克斯台岩体岩浆混合作用的时代为晚石炭世早期,表明西准噶尔地区在晚石炭世早期可能发生过强烈的壳-幔岩浆混合作用,并由地幔带来了铜、金等成矿物质,达尔布特构造岩浆带的壳幔岩浆混合作用可能是该岩浆带铜、金富集的主要原因。Abundant mafic microgranular enclaves,which show the characteristic of plastic deformation,are newly discovered in the Buerkesitai granite in the Tuoli County,Western Junggar,Xinjiang and are mainly distributed near around the Adayi gold deposit. LA-ICP-MS zircon U-Pb dating of the host rock and its enclaves indicates that the isotopic ages of the host rock and the enclave are 313. 7±2. 7 Ma（ 95% confidence,MSWD = 1. 8,n = 21）,and 312. 2±3. 9 Ma（ 95% confidence,MSWD = 2. 5,n = 26）,respectively,indicating that the host rock and its enclaves were formed in the same magma intrusion event. The Buerkesitai granite was formed by the intensive crust and mantle sourced magma mixing in the Western Junggar in Late Carboniferous. The ore-forming materials including copper and gold were derived from mantle by magma mixing which could be the main reason for the enrichment of copper and gold in the Darbut tectonomagmatic belt.

关 键 词：岩浆混合 U-PB年代学 闪长质包体 西准噶尔 

分 类 号：P597.3[天文地球—地球化学] P618.51[天文地球—地质学] P618.41