| 西藏羌塘中西部红脊山地区白云母花岗岩成因及地质意义 |
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| 引用本文： | 张乐,董永胜.西藏羌塘中西部红脊山地区白云母花岗岩成因及地质意义[J].世界地质,2017,36(3):671-681. |
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| 作者姓名： | 张乐 董永胜 |
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| 作者单位： | 1. 中陕核工业集团二一一大队有限公司, 西安 710024;2. 吉林大学地球科学学院, 长春 130061 |
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| 基金项目： | 国家自然科学基金项目（41372066）资助. |
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| 摘 要： | 在羌塘中西部红脊山地区一套二叠纪蛇绿岩中发现白云母花岗岩,呈脉状侵入到辉长岩-辉绿岩中。笔者对其进行详细的岩石学和地球化学研究,重点讨论其成因及地质意义。地球化学特征显示:白云母花岗岩具有高硅富碱的特点,属过铝质-钙碱性花岗岩;富集Th、Sr等元素,亏损Nb、Ta、Zr、Ti等元素;稀土元素球粒陨石标准化配分图显示U型曲线,正Eu异常明显。白云母花岗岩的岩石学特征、地球化学特征、元素比值及产出构造背景与仰冲型花岗岩类似。低CaO/Na_2O、高Al_2O_3/TiO_2及低全岩锆石饱和温度(T_(Zr)),说明其可能为蛇绿岩在仰冲就位的过程中,大陆边缘富白云母泥质岩石在低温、流体条件下,白云母脱水熔融形成。红脊山白云母花岗岩的发现表明,古特提斯洋盆已经闭合,羌北地块和羌南地块发生碰撞、对接。
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| 关 键 词： | 羌塘中西部 红脊山 地球化学 白云母花岗岩 西藏 |
| 收稿时间： | 2017-01-12 |
| 修稿时间： | 2017-07-28 |
Petrogenesis and geological implication of Hongji Mountain muscovite granite in central and western Qiangtang,Tibet |
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| ZHANG Le,DONG Yong-sheng.Petrogenesis and geological implication of Hongji Mountain muscovite granite in central and western Qiangtang,Tibet[J].World Geology,2017,36(3):671-681. |
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| Authors: | ZHANG Le DONG Yong-sheng |
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| Institution: | 1. Geological Party No. 211, Sino Shaanxi Nuclear Industry Group, Xi'an 710024, China;2. College of Earth Sciences, Jilin University, Changchun 130061, China |
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| Abstract: | The muscovite granite has been found in Permian ophiolite melange, which intruded into gabbro and diabase dikes as vein in Hongji Mountain, central and western Qiangtang. The authors studied the petrology and geochemistry characteristics, with an emphasis on its petrogenesis and geological implication. Geochemically, the muscovite granite is silica-rich in composition, with high content of alkali (Na2O+K2O). It's peraluminous granite that belongs to the calc-alkaline series and is characterized by the enrichment of Th, Sr and the depletion of Nb, Ta, Zr, Ti. The chondrite-normalized REE distribution patterns are characterized by U-shaped pattern with intensely positive Eu anomaly. The petrology, geochemistry, element ratios and tectonic setting of muscovite granite are similar to obduction-type granites. The muscovite granite has low CaO/Na2O, high Al2O3/TiO2 and low zircon saturation temperatures(TZr), indicating it was probably generated by dehydration-melting of muscovite-rich pelite in a condition of low temperature fluid on the continental margin, while the ophiolite melange obducted onto continental crust. The discovery of Hongji Mountain muscovite granite indicates that the Paleo-Tethys had been closed, and north Qiangtang collided and converged with south Qiangtang. |
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| Keywords: | central and western Qiangtang Hongji Mountain geochemistry muscovite granite Tibet |
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