阿勒泰南缘克朗盆地康布铁堡组流纹岩年代学、地球化学及岩石成因  

Chronology,Geochemistry and Petrogenesis of the Rhyolite in the Kangbutiebao Formation from the Kelang Basin at the Southern Margin of Altay,Xinjiang

作　　者：常好营 李永军[1,2] 陈博 周艳龙 高吉鹏 Chang Haoying;Li Yongjun;Chen Bo;Zhou Yanlong;Gao Jipeng(School of Earth Science and Resources,Chang’an University,Xi’an,Shaanxi,710054China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MLR,Xi’an,Shaanxi,710054,China;Xi’an Center of China Geological Survey,Xi’an,Shaanxi,710054,China)

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

出　　处：《新疆地质》2021年第1期10-20,共11页Xinjiang Geology

基　　金：天山-阿尔泰增生造山带大宗矿产资源基地深部探测技术示范项目(2018YFC060400)资助。

摘　　要：阿勒泰南缘克朗盆地康布铁堡组火山岩广泛分布。为查明克朗盆地康布铁堡组形成时代、源区及构造背景,对其中流纹岩进行了年代学、地球化学和锆石Hf同位素分析。在流纹岩中分别获得(394±1)Ma、(402.72±0.92)Ma的LA-ICP-MS锆石U-Pb年龄。地球化学特征显示,其为与“I”型花岗岩有相似特征的弱过铝质流纹岩,高SiO_(2)(73.58%~82.54%)、中等Al_(2)O_(3)(9.74%~13.29%,平均11.91%)及全碱含量(Na_(2)O+K_(2)O=4.11%~10.55%),低CaO(0.08%~3.34%,平均0.88%)、MgO(0.03%~2.72%,平均1.04%)。富集轻稀土,分布图呈右倾型。富集Rb,Th,U等大离子亲石元素,亏损Ba,Nb,Ta,Sr,Ti等,显著负Eu异常,锆石Hf同位素εHf(t)值为6.21~11.08、4.16~11.08。总体显示,该流纹岩形成于与俯冲作用有关的陆缘弧环境,为幔源岩浆加热上覆地壳进而发生部分熔融而成。Volcanic rocks are widely distributed in the Kangbutiebao Formation in the Kelang Basin on the southern margin of Altay.In order to ascertain the formation age,source area and tectonic background of the Kangbutiebao Formation in the Kelang Basin,the rhyolite in it was analyzed by chronology,geochemistry and zircon Hf isotope.The LA-ICPMS zircon U-Pb ages of(394±1)Ma and(402.72±0.92)Ma were obtained from the rhyolite.The geochemical characteristics show that it is a weak peraluminous rhyolite with similar characteristics to type-I granite,high SiO_(2)(73.58%~82.54%),medium Al_(2)O_(3)(9.74%~13.29%,average 11.91%)and total alkali content(Na_(2)O+K_(2)O=4.11%~10.55%),low CaO(0.08%~3.34%,average 0.88%),MgO(0.03%~2.72%,average 1.04%).Enriched LREES,the distribution map is right-leaning.Enrichment of LILES,such as Rb,Th,U and depletion of Ba,Nb,Ta,Sr,Ti etc.,and significant negativeδEu anomalies,zircon Hf isotopeεHf(t)values are 6.21-11.08,4.16-7.89,respectively.Overall,it shows that the rhyolite was formed in a continental arc environment related to subduction,which was caused by partial melting of the crustthat was induced by mantle-derived magma.

关 键 词：地球化学 火山岩 HF同位素 康布铁堡组 阿勒泰南缘 

分 类 号：P588.141[天文地球—岩石学] P595[天文地球—地质学]