| 阿拉善地块南缘野芨里镁铁-超镁铁质岩体锆石U-Pb年龄及其地质意义 |
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| 引用本文： | 焦建刚,马泽民,鲁浩,高栋,张国鹏,邵乐奇.阿拉善地块南缘野芨里镁铁-超镁铁质岩体锆石U-Pb年龄及其地质意义[J].大地构造与成矿学,2017,41(5):950-959. |
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| 作者姓名： | 焦建刚 马泽民 鲁浩 高栋 张国鹏 邵乐奇 |
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| 作者单位： | 1. 长安大学地球科学与资源学院,陕西西安710054;西部矿产资源与地质工程教育部重点实验室,陕西西安710054;国土资源部岩浆作用成矿与找矿重点实验室,陕西西安710054;2. 长安大学地球科学与资源学院,陕西西安,710054;3. 山东省地矿局第三地质矿产勘查院,山东烟台,264004 |
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| 基金项目： | 国家自然科学基金项目，公益性行业科研专项 |
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| 摘 要： | 阿拉善地块南缘北大山地区野芨里镁铁-超镁铁质岩体主要由单辉橄榄岩、二辉橄榄岩、橄榄辉长岩组成。岩体局部发现了硫化物,主要由磁黄铁矿、镍黄铁矿与黄铜矿组成,指示岩浆结晶过程中发生了硫化物不混溶作用。岩石地球化学分析显示野芨里岩体属于铁质超基性岩,富集大离子亲石元素,相对亏损高场强元素,具有明显的Nb,Ta负异常,微量元素比值指示岩浆在上升过程中受到了中上地壳物质混染。橄榄辉长岩中锆石SHRIMP U-Pb年龄为286.6±2.5 Ma,属于早二叠世。结合区域构造演化,认为野芨里岩体形成背景可能与古亚洲洋的闭合或俯冲之后的伸展作用相关。
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| 关 键 词： | 年代学 岩石地球化学 岩浆演化 构造背景 野芨里岩体 |
Zircon U-Pb Dating of Yejili Mafic-ultramafic Intrusion in Southern Margin of Alxa Block,and its Geological Implication |
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| JIAO Jiangang,MA Zemin,LU Hao,GAO Dong,ZHANG Guopeng,SHAO Leqi.Zircon U-Pb Dating of Yejili Mafic-ultramafic Intrusion in Southern Margin of Alxa Block,and its Geological Implication[J].Geotectonica et Metallogenia,2017,41(5):950-959. |
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| Authors: | JIAO Jiangang MA Zemin LU Hao GAO Dong ZHANG Guopeng SHAO Leqi |
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| Abstract: | The Yejili mafic-ultramafic intrusion,which is located in southern margin of Alxa block,mainly consists of peridotite,lherzolite,and olivine gabbro.The locally distributed sulfides such as pyrrhotite,pentlandite,and chalcopyrite indicate that sulfide saturation took place during the magma crystallization.On the base of geochemistry data,the Yejili intrusion belongs to ferro-ultrabasic rocks.The rocks are rich in LREE and low in Nb,Ta.The positive εNd(t) values of rocks demonstrate that the intrusion is likely derived from partial melting of depleted lithosphere mantle,and experienced middle-upper crust contamination.The zircon U-Pb age of the olivine gabbro is 286.6±2.5 Ma,which is consistent with the age of regional magmatism,suggesting that the emplacement of the Yejili intrusion was related to the closure of the Paleo-Asian Ocean or an extensional regime in a post-collision setting. |
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| Keywords: | chronology geochemistry magma evolution tectonic setting Yejili intrusions |
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