| 西准噶尔谢米斯台西段花岗岩年代学、地球化学、锆石Lu-Hf同位素特征及大地构造意义 |
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| 引用本文： | 杨钢,肖龙,王国灿,高睿,贺新星,鄢圣武,杨维,晏文博,周佩.西准噶尔谢米斯台西段花岗岩年代学、地球化学、锆石Lu-Hf同位素特征及大地构造意义[J].地球科学,2015,40(3):548-562. |
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| 作者姓名： | 杨钢 肖龙 王国灿 高睿 贺新星 鄢圣武 杨维 晏文博 周佩 |
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| 作者单位： | 1.中国地震局地震研究所地震大地测量重点实验室, 湖北武汉 430071 |
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| 基金项目： | 中国地质调查局项目“西准噶尔克拉玛依后山地区三维地质调查试点”(No.1212011220245);新疆1∶25万铁厂沟镇幅(L45C002001)与克拉玛依市幅(L45C003001)区调修测项目(No.1212011120502) |
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| 摘 要： | 西准噶尔谢米斯台花岗岩研究程度偏低, 运用锆石LA-ICP-MS U-Pb年代学、地球化学及锆石Lu-Hf同位素方法研究西准谢米斯台西段地区花岗岩, 结果表明: 谢米斯台岩体(427.6±2.3 Ma)和哈勒盖特希岩体(428.6±2.5 Ma)均形成于中志留世; 谢米斯台碱长花岗岩地球化学特征类似于Ⅰ型花岗岩, 哈勒盖特希碱长花岗岩地球化学特征类似于A型花岗岩; 锆石Hf同位素组成较均一, εHf(t)=12.4~14.5, 二阶段模式年龄tDM2变化范围在497~603 Ma之间, Ⅰ型花岗岩和A2型花岗岩可能形成于后碰撞阶段的挤压-伸展转变期, 是中志留世额尔齐斯-斋桑洋壳向南俯冲至波谢库尔-成吉斯火山弧底部, 俯冲板片与岛弧底部岩石圈之间剪切带的物质发生变形、变质及部分熔融作用, 使得由亏损地幔形成不久的年轻地壳(由洋壳和岛弧组成)发生部分熔融形成的长英质岩浆经进一步分离结晶作用形成分异Ⅰ型花岗岩和高温、缺水A2型花岗岩, A2型花岗岩较Ⅰ型花岗岩分离结晶程度高.
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| 关 键 词： | 锆石LA-ICP-MS U-Pb年龄 谢米斯台西段 Hf同位素 A型花岗岩 地球化学 |
| 收稿时间： | 2014-05-06 |
Geochronology,Geochemistry and Zircon Lu-Hf Study of Granites in Western Section of Xiemisitai Area,Western Junggar |
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| Yang Gang;Xiao Long;Wang Guocan;Gao Rui;He Xinxing;Yan Shengwu;Yang Wei;Yan Wenbo;Zhou Pei.Geochronology,Geochemistry and Zircon Lu-Hf Study of Granites in Western Section of Xiemisitai Area,Western Junggar[J].Earth Science-Journal of China University of Geosciences,2015,40(3):548-562. |
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| Authors: | Yang Gang;Xiao Long;Wang Guocan;Gao Rui;He Xinxing;Yan Shengwu;Yang Wei;Yan Wenbo;Zhou Pei |
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| Institution: | Yang Gang;Xiao Long;Wang Guocan;Gao Rui;He Xinxing;Yan Shengwu;Yang Wei;Yan Wenbo;Zhou Pei;Key Laboratory of Earthquake Geodesy,Institute of Earthquake,China Earthquake Administration;School of Earth Sciences,China University of Geosciences;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences;College of Earth Sciences,Chengdu University of Technology;Geological Survey of Jiangsu Province;Geological Survey of Sichuan Province;Institute of Geological Prospecting,Coal Mine Exploration of Guizhou Province; |
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| Abstract: | LA-ICP-MS U-Pb zircon age, geochemistry and Lu-Hf isotopic data for Xiemisitai and Halegaitexi granitic plutons in the western Junggar are presented in this paper, aiming to determine their forming ages, source regions and tectonic settings. LA-ICP-MS zircon yields 427.6±2.3 Ma for Xiemisitai alkali feldspar granites and 428.6±2.5 Ma for Halegaitexi alkali feldspar granites, respectively. Xiemisitai alkali feldspar granites are characterized as the Ⅰ-type granite, while Halegaitexi alkali feldspar granites have geochemical characteristics similar to the A-type granite. Zircon Lu-Hf isotopic compositions indicate that εHf(t)=12.4-14.5, two-stage model ages (tDM2) range from 497 to 603 Ma. The petrogenesis of Ⅰ-type and A-type granites were results of different evolutive phases of the same source magma in the compressible to extendable period of the post-collisional phase, which may be derived as follows. The southward subductional Irtysh-Zaysan Oceanic crust subductioned to the asthenospheric mantle which is the bottom of Boshchekul-Chingiz volcanic arc, resulted in the asthenospheric mafic magma underplating the lower crust. Then, the lower juvenile basaltic crust derived from the depleted mantle underwent different degrees of partial melting and fractional crystallization to a certain extent to generate the Ⅰ-type and A2-type granites. |
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