| 滇东南老君山地区片麻状花岗岩年代学、地球化学特征及构造意义 |
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| 引用本文： | 黄孔文,张达,阙朝阳,狄永军.滇东南老君山地区片麻状花岗岩年代学、地球化学特征及构造意义[J].华南地质与矿产,2019,35(2):186-199. |
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| 作者姓名： | 黄孔文 张达 阙朝阳 狄永军 |
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| 作者单位： | 广东省地质调查院,广州,510080;中国地质大学地球科学与资源学院,北京100083;中国地质大学岩石圈构造、深部过程及探测技术教育部重点实验室,北京100083;紫金矿业集团西南有限公司,昆明,650051;中国地质大学地球科学与资源学院,北京,100083 |
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| 基金项目： | 云南省麻栗坡县政府委托项目;高等学校学科创新引智计划计划) |
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| 摘 要： | 本文对滇东南老君山地区南捞片麻状花岗岩进行岩石学、锆石U-Pb年代学、地球化学和Hf同位素等方面的研究,以探讨其岩石成因和构造意义。研究结果表明岩体地球化学上具有高硅,富碱和高铝特点;稀土配方模式呈现轻稀土富集略右倾斜型,轻稀土分馏明显,存在明显Eu负异常;相对亏损Rb、Ba、Pb、Sr、Ti、Eu、Yb等元素,相对富集Th、K、Pr、Nd、Sm、Hf和Tb等元素。样品LA-ICP-MS锆石U-Pb年龄为431.8±4.1Ma。锆石Hf同位素研究结果表明,εHf(t)=0.8^-11.70,其两阶段模式年龄(T2DM)主要为1395~1544Ma。上述地球化学及年代学研究结果表明南捞片麻状花岗岩主要来自中元古代下地壳物质部分熔融,为有幔源物质的参与形成的I型花岗岩。结合华南加里东期成岩构造环境,判断滇东南老君山早期南捞岩体形成于后造山伸展环境。
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| 关 键 词： | 南捞片麻状花岗岩 锆石U-PB年代学 地球化学 构造意义 云南老君山地区 |
Geochemistry and Geochronology Characteristics of Nanlao Gneissic Granites in the Laojunshan Area of Southeastern Yunnan,and Its Tectonic Signigicance |
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| HUANG Kong-Wen,ZHANG Da,QUE Chao-Yang,DI Yong-Jun.Geochemistry and Geochronology Characteristics of Nanlao Gneissic Granites in the Laojunshan Area of Southeastern Yunnan,and Its Tectonic Signigicance[J].Geology and Mineral Resources of South China,2019,35(2):186-199. |
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| Authors: | HUANG Kong-Wen ZHANG Da QUE Chao-Yang DI Yong-Jun |
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| Institution: | (Guangdong Geological Survey,Guangzhou 510080,Guangdong,China;School of Earth Science and Resource,China University of Geosciences,Beijing 100083,China;Key Laboratory of Lithospheric Structure,Deep Process and Exploration Technology of Ministry of Education,China University of Geosciences,Beijing 100083,China;Zinjin Mining Group Southwest Co.Ltd,Kunming 650051,Yunnan,China) |
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| Abstract: | This paper deals with the petrology, zircon U-Pb chronology, geochemistry and Hf isotope of Nanlao gneissic granite in Laojunshan area, southeastern Yunnan, in order to explore its petrogenesis and tectonic significance. The results show that the Nanlao gneissic granite is geochemically characterized by high silicon, alkali-rich and high aluminium content;the REE formula model shows a slightly right-leaning type of enrichment of light REEs, with obvious fractionation of light REEs and obvious negative Eu anomalies;it is relatively depleted in Rb, Ba, Pb, Sr, Ti, Eu and Yb, and relatively enriched in Th, K, Pr, Nd, Sm, Hf and Tb. The LA-ICP-MS zircon U-Pb age of the sample is 431.8+4.1 Ma. The results of zircon Hf isotope study show that the age of the two-stage model (T2DM) is mainly 1 395-1 544 Ma, and the value of εHf (t)= 0.8-11.70. The above geochemical and chronological studies show that Nanlao gneissic granite is mainly derived from the partial melting of lower crustal material of the Mesoproterozoic, and is a I-type granite formed with the participation of mantle-derived materials. Based on the Caledonian diagenetic tectonic setting in South China, the Nanlao intrusion in the early Laojunshan area in southeastern Yunnan is formed in the post-orogenic extensional environment. |
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| Keywords: | Nanlao gneissic granites zircon U-Pb geochronology geochemistry tectonic signigicance Laojunshan area Southeastern Yunnan Province |
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