| 西准噶尔别鲁阿嘎希花岗闪长岩年代学、地球化学特征及岩石成因 |
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| 引用本文： | 杨钢,肖龙,王国灿,高睿,贺新星,张雷,周佩.西准噶尔别鲁阿嘎希花岗闪长岩年代学、地球化学特征及岩石成因[J].地球科学,2015,40(5):810-823. |
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| 作者姓名： | 杨钢 肖龙 王国灿 高睿 贺新星 张雷 周佩 |
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| 作者单位： | 1.中国地震局地震研究所地震预警湖北省重点实验室，湖北武汉 430071 |
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| 基金项目： | 中国地质调查局项目，新疆1∶25万铁厂沟镇幅，克拉玛依市幅(L45C003001)区调修测项目 |
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| 摘 要： | 为更深入了解西准噶尔晚古生代岩浆活动和构造背景，对位于西准噶尔中部的别鲁阿嘎希岩体开展了年代学、地球化学以及Sr-Nd同位素研究，讨论了岩石成因、源区性质和构造背景.别鲁阿嘎希花岗闪长岩为钙碱性系列岩石，岩浆锆石结晶年龄为318.7±3.3 Ma.其具相对高的MgO(Mg#=49~59)、Ni、Cr含量，富集大离子亲石元素(如K、Rb、Sr和Ba)、亏损高强场元素(如Nb、Ta、Ti)，轻重稀土元素分异不明显.Sr-Nd同位素特征显示，其有较低的初始Sr比值(0.704 297~0.704 399)，较高的εNd(t)值(5.8~6.5).通过综合分析，认为在晚石炭世早期，达尔布特洋壳(板片)俯冲至地幔楔下部，俯冲洋壳板片脱水所产生的流体在上升过程中与地幔楔共同作用，底侵加热由亏损地幔形成不久的年轻地壳(由洋壳和岛弧组成)，使其部分熔融形成了别鲁阿嘎希分异I型花岗岩.
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| 关 键 词： | 别鲁阿嘎希岩体 地质年代学 地球化学 Sr-Nd同位素 西准噶尔 地层学 |
| 收稿时间： | 2014-09-20 |
Geochronological,Geochemical and Petrogenesis of Bieluagaxi Granodioritic Pluton in Western Junggar |
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| Yang Gang,Xiao Long,Wang Guocan,Gao Rui,He Xinxing,Zhang Lei,Zhou Pei.Geochronological,Geochemical and Petrogenesis of Bieluagaxi Granodioritic Pluton in Western Junggar[J].Earth Science-Journal of China University of Geosciences,2015,40(5):810-823. |
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| Authors: | Yang Gang Xiao Long Wang Guocan Gao Rui He Xinxing Zhang Lei Zhou Pei |
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| Abstract: | For a better understanding of the petrogenesis and tectonic environment of the acidic intrusive rocks in Western Junggar, a study is carried out on Bieluagaxi granodioritic pluton located in the Central part of West Junggar. Its petrogenesis, magma source, tectonics setting based on petrography, zircon LA-ICP-MS U-Pb ages, whole-rock major and trace elements, and Sr-Nd isotopic compositions are discussed in detail. LA-ICP-MS U-Pb zircon data of the granodiorite give weighted ages of 318.7±3.3 Ma. Bieluagaxi granodiorite is calc-alkaline suite with high MgO(Mg#=49-59), Ni and Cr contents. Bieluagaxi granodiorite is strongly enriched in large ion lithophile elements (LILEs, e.g. K, Rb, Sr and Ba), but it displays depletion of high field strength elements (HFSEs, e.g. Nb, Ta and Ti). In terms of Sr-Nd isotopic compositions, granodiorite has low initial 87Sr/86Sr ratios (0.704 297-0.704 399) and high positive εNd(t) (5.8-6.5). Therefore, we suggest that the early Late Carboniferous Bieluagaxi granodioritic pluton has been generated in a subduction setting, the mantle wedge began to partially melt due to the upward fluid from the dehydration of subducting oceanic slab, resulting in the asthenospheric mafic magma underplating the lower crust. Then, the lower juvenile basaltic crust derived from the depleted mantle underwent partial melting to generate the I type granites of the Bieluagaxi granodioritic pluton. |
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| Keywords: | Bieluagaxi granodioritic pluton geochronology geochemistry Sr-Nd isotope western Junggar stratigraphy |
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