| 中天山天湖东铁钼矿含矿片麻状花岗岩年代学、地球化学和锆石Hf同位素-对于中天山早古生代构造演化的启示 |
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| 引用本文： | 雷如雄,吴昌志,屈迅,顾连兴,陈刚,吾尔娜,孙洪涛,刘国宁.中天山天湖东铁钼矿含矿片麻状花岗岩年代学、地球化学和锆石Hf同位素-对于中天山早古生代构造演化的启示[J].吉林大学学报(地球科学版),2014,44(5):1540-1552. |
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| 作者姓名： | 雷如雄 吴昌志 屈迅 顾连兴 陈刚 吾尔娜 孙洪涛 刘国宁 |
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| 作者单位： | 1.长安大学地球科学与资源学院，西安710054;
2.西部矿产资源与地质工程教育部重点实验室，西安710054;
3.南京大学地球科学与工程学院，南京210093;
4.新疆维吾尔自治区地质矿产勘查开发局，乌鲁木齐830000;
5.江苏省有色金属华东地质勘查局，南京210007 |
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| 基金项目： | 国家自然科学基金项目(41302069，41272098)；中国地质调查局地质调查工作项目 |
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| 摘 要： | 以中天山东段的天湖东铁钼矿含矿花岗岩为例，在LA-ICP-MS锆石U-Pb年代学测定其为早古生代花岗岩（（445.3±4.6） Ma）基础上，通过岩相学、地球化学及锆石原位Hf同位素组成等多方面研究，探讨该岩体的成岩作用及其构造背景。天湖东含矿片麻状花岗岩的主要矿物为斜长石、石英、钾长石，并含少量黑云母和角闪石等。全岩地球化学分析结果表明，该片麻状花岗岩高硅、弱富铝、富钙、富钠而贫钾，ASI值为0.68~0.82，属于准铝质钙碱性花岗岩，总体上富集大离子亲石元素（LILE）Rb、Ba等和轻稀土元素La、Ce、Nd等，而亏损高场强元素Nb、Ta、Ti、Yb等，轻重稀土分异明显，轻稀土分异较为明显，而重稀土分异不明显，表现出典型岛弧岩浆岩的地球化学特征。锆石的εHf(445 Ma)值为-6.31~-1.77，二阶段Hf模式年龄（TDM2）为1.538~1.825 Ga，表明该花岗岩的源区主要为壳源物质。综合分析上述资料，认为天湖东铁钼矿片麻状花岗岩是由俯冲过程中地壳物质重熔的产物。结合前人的研究和本课题组的新近研究成果认为，在早古生代时，中天山为岩浆弧构造环境，形成一系列的钙碱性岩浆岩，而该岩浆弧的形成可能是受到介于吐哈陆块和塔里木板块之间的古天山大洋在早古生代时期向南俯冲而形成的。
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| 关 键 词： | 锆石U-Pb年代学 Hf同位素 地球化学 花岗岩 中天山 天湖东铁钼矿 |
| 收稿时间： | 2013-10-10 |
Geochronology,Geochemistry and Zircon Hf Isotope Compositions of the Ore-Bearing Gneiss Granite in the Tianhudong Iron-Molybdenum Ore Deposit in the Central Tianshan,West China:Implications for the Early Paleozoic Tectonic Evolution of Central Tianshan |
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| Lei Ruxiong,Wu Changzhi,Qu Xun,Gu Lianxing,Chen Gang,Uerna Amy,Sun Hongtao,Liu Guoling.Geochronology,Geochemistry and Zircon Hf Isotope Compositions of the Ore-Bearing Gneiss Granite in the Tianhudong Iron-Molybdenum Ore Deposit in the Central Tianshan,West China:Implications for the Early Paleozoic Tectonic Evolution of Central Tianshan[J].Journal of Jilin Unviersity:Earth Science Edition,2014,44(5):1540-1552. |
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| Authors: | Lei Ruxiong Wu Changzhi Qu Xun Gu Lianxing Chen Gang Uerna Amy Sun Hongtao Liu Guoling |
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| Institution: | Lei Ruxiong;Wu Changzhi;Qu Xun;Gu Lianxing;Chen Gang;Uerna Amy;Sun Hongtao;Liu Guoling;College of Earth Sciences and Resource,Chang’an University;Key Laboratory of Western China’s Mineral Resources and Geological Engineering Ministry of Education;School of Earth Sciences and Engineering,Nanjing University;Xinjiang Bureau of Geology and Mineral Resources;Eastern China Geoexploration&Development Bureau for Non-Ferrous Metals,Jiangsu Province; |
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| Abstract: | We present a case study of the Early Paleozoic ore bearing gneiss granite in the Tianhudong iron-molybdenum ore deposit in the central Tianshan in an attempt to provide new insights for the early Paleozoic tectonic setting and tectonic evolution of the central Tianshan. LA-ICP-MS zircon U-Pb dating yields （445.3±4.6） Ma for the studied granite. The granite is composed mainly of biotite, amphibole, quartz, plagioclase and K-feldspar. Geochemical analyses show the granite belongs to subaluminous calc-alkaline granite. The granite is generally enriched in large ion lithophile elements (LILEs) such as Rb, Ba and LREEs, but depleted in typical high field strength elements (HFSEs) such as Nb, Ta, Ti, Y and HREEs, consistent with the geochemical characteristics of typical arc igneous rock. The zircon Hf isotope compositions (εHf(445 Ma)) of the studied granite vary from -6.30 to -1.77, and the TDM2 ranges from 1.538 to 1.825 Ga, indicating the source rocks of the granite contain significant crustal materials. Integrating all the available data, we suggest that the granite is produced by melting of the mainly crustal protolith during a subduction process. Combined with the previous studies and our recent study results, it is suggested that the central Tianshan zone was a magmatic arc tectonic environment during the Early Paleozoic. The mechanism of the Early Paleozoic central Tianshan arc can be ascribed to the southern subduction of the ancient Tianshan ocean located between the Tuha block and Tarim block. |
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| Keywords: | zircon U Pb dating Hf isotope geochemistry granites central Tianshan Tianhudong iron-molybdenum ore deposit |
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