| 内蒙古阿拉善北部陶豪托西圈辉长岩LA-ICP-MS
锆石U-Pb年龄和地球化学特征 |
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| 引用本文： | 张 磊,史兴俊,张建军,杨奇荻,童 英,王 涛.内蒙古阿拉善北部陶豪托西圈辉长岩LA-ICP-MS
锆石U-Pb年龄和地球化学特征[J].地质通报,2013,32(10):1536-1547. |
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| 作者姓名： | 张 磊 史兴俊 张建军 杨奇荻 童 英 王 涛 |
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| 作者单位： | 1.中国地质科学院地质研究所，北京100037；
2.中国地质大学，北京100083 |
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| 摘 要： | 在内蒙古阿拉善地区北部庆格勒图附近零星分布着数个基性侵入岩体，陶豪托西圈辉长岩是其中最大的一个。早期资料显示，这些基性侵入岩可能形成于早古生代。2件陶豪托西圈辉长岩样品的LA-ICP-MS锆石U-Pb年龄结果一致，表明其形成时代为276~275Ma，相当于早二叠世晚期。地球化学特征表明，陶豪托西圈辉长岩中存在早期分离结晶所形成的斜长石的富集，而其中Nb的负异常可能是源区特征的反映，暗示着该岩体可能形成于俯冲背景下，而不是伸展环境下的产物。结合区域地质资料，阿拉善北部晚石炭世—二叠纪的岩浆活动存在幔源岩浆的强烈参与，这一时期该地区可能属于俯冲背景下的岩浆弧。
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| 关 键 词： | 辉长岩 锆石U-Pb年龄 早二叠世 地球化学 阿拉善 |
LA-ICP-MS zircon U-Pb age and geochemical characteristics of the Taohaotuoxiquan gabbro in northern Alxa, Inner Mongolia |
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| ZHANG Lei,SHI Xing-jun,ZHANG Jian-jun,YANG Qi-di,TONG Ying,WANG Tao.LA-ICP-MS zircon U-Pb age and geochemical characteristics of the Taohaotuoxiquan gabbro in northern Alxa, Inner Mongolia[J].Geologcal Bulletin OF China,2013,32(10):1536-1547. |
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| Authors: | ZHANG Lei SHI Xing-jun ZHANG Jian-jun YANG Qi-di TONG Ying WANG Tao |
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| Institution: | 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;
2. China University of Geosciences, Beijing 100083, China |
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| Abstract: | In Qinggeletu area of northern Alxa within Inner Mongolia, several mafic plutons are sporadically outcropped, of which the Taohaotuoxiquan gabbro is the largest one. These mafic plutons were previously considered to be Early Paleozoic in age. LA-ICP-MS zircon U-Pb dating of two samples from Taohaotuoxiquan gabbro yielded a consistent age of 276~275Ma, suggesting an emplacement of Early Permian. Geochemical characteristics of the Taohaotuoxiquan gabbro indicate that it contains some fractional crystallized plagioclase with the Nb negative anomaly inherited from its source, implying that this gabbro was formed in a subduction setting rather than in the continental rift. Combined with previous studies, the authors hold that a large amount of mantle-derived melt was involved in Late Carboniferous-Permian magmatism in northern Alxa, and this area might have been an arc in a subduction setting at that time. |
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| Keywords: | gabbro zircon U-Pb age Early Permian geochemistry Alxa |
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