| 引用本文: | 付建刚, 李光明, 董随亮, 张海, 郭伟康, 张林奎, 梁维, 焦彦杰, 凌晨.西藏拉隆穹窿淡色花岗岩中石榴子石矿物学研究及对岩浆-热液过程的指示[J].沉积与特提斯地质,2022,42(2):288-299.[点击复制] |
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| 西藏拉隆穹窿淡色花岗岩中石榴子石矿物学研究及对岩浆-热液过程的指示 |
| 付建刚,李光明,董随亮,张海,郭伟康,张林奎,梁维,焦彦杰,凌晨 |
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(1. 中国地质调查局成都地质调查中心, 四川 成都 610081;
2. 成都理工大学, 四川 成都 610059) |
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| 摘要: |
| 为建立淡色花岗岩演化和稀有金属成矿的矿物学指标，本文选取了北喜马拉雅拉隆淡色花岗岩的石榴子石为研究对象，对其开展电子探针分析和矿物原位LA-ICP-MS微量分析，结果表明MnO含量从白云母花岗岩(12.42%~13.48%)到钠长石花岗岩(16.83%~22.09%)逐渐增高，白云母花岗岩石榴子石主要为铁铝榴石，钠长石花岗岩中石榴子石主要为锰铝榴石，其均为典型岩浆成因的石榴子石。石榴子石微量元素结果显示白云母花岗岩和钠长石花岗岩石榴子石稀土均呈现HREE富集、LREE亏损，Eu负异常的特征。从白云母花岗岩到钠长石花岗岩，石榴子石中Zn含量增加，Sc、Y和HREE等元素含量降低，特别是当HREE含量小于1000×10-6时，稀有金属元素Be、Nb和Ta含量增加，标志着岩浆演化从正岩浆阶段进入了岩浆-热液过渡阶段。形成于岩浆-热液过渡阶段的锰铝榴石可以作为拉隆淡色花岗岩Be-Nb-Ta稀有金属矿化的矿物学指标，此外，石榴子石中Sc、Y和HREE等元素的变化也可以作为淡色花岗岩稀有金属矿化的判别标志。 |
| 关键词: 石榴子石 矿物微量 Be-Nb-Ta稀有金属 淡色石花岗岩 拉隆穹窿 北喜马拉雅 |
| DOI：10.19826/j.cnki.1009-3850.2021.09002 |
| 附件 |
| 投稿时间：2021-04-16修订日期：2021-08-18 |
| 基金项目:第二次青藏高原综合科学考察研究资助(2019QZKK0806)、国家自然科学基金项目(批准号：91955208,41602214)、国家重点研发计划项目“我国西部伟晶岩型锂等稀有金属成矿规律与勘查技术”课题“北喜马拉雅锂等稀有金属找矿预测与勘查示范“(编号：2021YFC2901903)、中国地质调查局“西藏山南地区铍锡多金属矿调查评价”(编号：DD20190147)、国家科学技术部“青藏高原典型矿集区透明化与矿体定位预测”(编号：2016YFC060308)、“青藏高原重要矿产资源基地成矿系统深部探测技术与勘查增储示范”(编号：2018YFC0604103)联合资助 |
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| Mineral chemistry of garnet and its implication for the magmatic-hydrothermal transition in rare metal leucogranites in the Lalong dome, southern Tibet, China |
| FU Jiangang, LI Guangming, DONG Suiliang, ZHANG Hai, GUO Weikang, ZHANG Linkui, LIANG Wei, JIAO Yanjie, LING Chen |
(1. Chengdu Center, China Geological Survey, Chengdu 610081, China;
2. Chengdu University of Technology, Chengdu 610059, China) |
| Abstract: |
| In order to acquire a mineralogical indicator for the degree of leucogranite magmatic evolution and the mineralization of Be-Nb-Ta rare metals, the garnets of the Lalong dome, located at the eastern part of the North Himalayan Gneiss Domes (NHGD), was performed Electron probe analysis and in-suit LA-ICP-MS analysis. Major elements results in garnet show that MnO contents range from 12.42%~13.48% in muscovite granite to 16.83%~22.09% in albite granite. Almandite mainly occur in muscovite granite, while spessartite in albite granite, both types resulted from magmatic crystallization. Trace elements results show that garnets in muscovite granite and albite granite are characterized by the enrichment of heavy rare earth elements (HREE), high depletion in light rare earth elements (LREE), and the negative Eu anomalies. With the increasing degree of magma differentiation evolution from muscovite granite to albite granite, Zn, Be, Nb and Ta contents in garnet gradually increase with the degree of magma evolution, while Sc, Y and HREE contents decrease, which indicates that the magma evolution has changed from normal magma stage to the magmatic-hydrothermal transition stage. Spessartite in albite granite can be used as a mineralogical indicator for the mineralization of Be-Nb-Ta rare metals in Lalong Dome. |
| Key words: garnet mineral trace element Be-Nb-Ta rare metal leucogranite Lalong dome Northern Himalaya |