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现代地质 ›› 2015, Vol. 29 ›› Issue (3): 529-541.

• 岩石学 • 上一篇    下一篇

西天山伊犁地块北缘桦木沟高分异I型花岗岩年代学、地球化学及其构造意义

王永文1,2,颜丹平1,刘红旭1,2,潘澄雨2,陈峰1,2,孟云飞1,2,丁波2,刘涛2   


  1. (1. 中国地质大学(北京)地球科学与资源学院,北京 100083;2. 核工业北京地质研究院,北京 100029)
  • 出版日期:2015-06-10 发布日期:2015-07-08
  • 作者简介:王永文,男,硕士研究生,1989年出生,构造地质学专业,从事构造地球化学研究。Email:wangyongwen2013@163.com。
  • 基金资助:

    国家“973”项目(2015CB453004);国家“863”项目(2012AA061801)。

Geochronology,Geochemistry and Tectonic Significance of  Huamugou Highly Fractionated I-type Granitoid Pluton in  Northern Yili Block, Western Tianshan


WANG Yong-wen1,2,YAN Dan-ping1,LIU Hong-xu1,2,PAN Cheng-yu2,CHEN Feng1,2,MENG Yun-fei1,2,DING Bo2,LIU Tao2   


  1. (1.School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083,China;
     2.Beijing Research Institute of Uranium Geology, Beijing 100029,China)
  • Online:2015-06-10 Published:2015-07-08

摘要:

古生代晚期天山造山带经历了洋壳消减及地块拼合的过程,西天山伊犁地块周缘拼合带的花岗岩岩浆记录可以为俯冲造山作用时限提供有效的约束。岩石地球化学和年代学分析显示,位于伊犁地块北缘的桦木沟花岗岩体高硅,富碱,贫铁,富集HFSE,具强烈铕负异常,亏损Ba、Sr、P、Ti,富集Cs、Rb、U、K,与高分异I型花岗岩地球化学特征一致;Pb同位素指示花岗岩源区为造山带下地壳;LA-ICP-MS锆石U-Pb测年结果表明,该岩体结晶年龄为(330.2±5.7) Ma,说明桦木沟岩体产于汇聚大陆边缘,天山北部洋壳在早石炭世晚期仍在向南俯冲,准噶尔地块与伊犁地块还未碰撞拼合,天山地区可能正处于俯冲消减阶段。

关键词: 天山, 伊犁地块, 高分异I型花岗岩, 锆石U-Pb定年, 桦木沟岩体, 俯冲

Abstract:

The Tianshan orogenic belt experienced a subduction and split plots during Late Paleozoic. Records of granite magma records provide important constraints on timing of subduction. The geochemical and chronological results show that Huamugou pluton is consistent with highly fractionated I-type granite of high silicon, rich alkali, poor iron. Ba, Sr, P, Ti are poorly concentrated and Cs, Rb, U, K are well concentrated. Pb isotope studies suggest crustal source with added mantle material. The LA-ICP-MS zircon U-Pb dating on zircons yields age of (330.2±5.7) Ma, belonging to the late Early Carboniferous. These geochemical characteristics indicate that the Huamugou pluton formed in a continental arc setting. Northern Tianshan oceanic crust still southward subducted in the late Early Carboniferous and Junggar plate is not collided with Yili plate, which shows that the Tianshan region is in the subduction stage.

Key words: Tianshan, Yili block, highly fractionated I-type granite, U-Pb zircon dating, Huamugou pluton, subduction

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