| 新疆大红柳滩稀有金属矿田花岗岩与伟晶岩成因关系探讨 |
| Received:April 27, 2022 Revised:March 03, 2023 点此下载全文 |
| 引用本文：HE Lei,GAO JingGang,WANG DengHong,LIANG Ting,FENG YongGang,HUANG Fan,TAN XiJuan,CEN JuBiao.2023.Discussion on genetic relationship between granite and pegmatite in Dahongliutan rare metal ore field, Xinjiang[J].Mineral Deposits,42(4):693~712 |
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| Author Name | Affiliation | E-mail | | HE Lei | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | | | GAO JingGang | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | jggao@chd.edu.cn;黄凡，hfhymn@163.com | | WANG DengHong | Key Laboratory of Mineralization and Resource Evaluation, Ministry of Natural Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | | | LIANG Ting | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | | | FENG YongGang | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | | | HUANG Fan | Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China
Key Laboratory of Mineralization and Resource Evaluation, Ministry of Natural Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China | hfhymn@163.com | | TAN XiJuan | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | | | CEN JuBiao | School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China
Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals, Xi'an 710054, Shaanxi, China | |
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| 基金项目:本文得到国家重点研发计划项目(编号:2021YFC2901902、2017YFC0602701)、西安市关键金属成矿与高效利用重点实验室(编号:300102272502、300102272504)和陕西省自然科学基金(编号:2021JM-162)共同资助 |
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| 中文摘要:西昆仑大红柳滩稀有金属矿田出露大面积的复式花岗岩体和数千条花岗伟晶岩脉,含锂和富锂伟晶岩脉分布在巴颜喀拉山群、石英闪长岩、黑云母二长花岗岩的内部以及二云母二长花岗岩和石榴子石电气石二云母二长花岗岩的边缘或者外围,围绕复式岩体存在明显的矿物组合分带特征。富锂伟晶岩与二云母二长花岗岩、石榴子石电气石二云母二长花岗岩的空间关系更加密切。野外地质特征和精确的年代学数据显示:复式岩体主要由先后侵入的片麻状石英闪长岩、黑云母二长花岗岩和二云母二长花岗岩组成,锆石U-Pb年龄分别为214.7~213.7 Ma,214~213 Ma和209.6~208.8 Ma;花岗伟晶岩的锡石、锆石、独居石、铌钽矿物U-Pb年龄分别为223~207.4 Ma,显示花岗伟晶岩与复式岩体具有密切的时空关系。石英闪长岩、黑云母二长花岗岩和二云母二长花岗岩具有不同的岩石地球化学、εHf(t)值、εNd(t)值和δ7Li同位素特征,显示三者来源于不同的岩浆源区。二云母二长花岗和石榴子石电气石二云母二长花岗岩具有相似的εHf(t)值(-9.49~-4.47)和εNd(t)值(-8.64~-7.81),表明其源于下地壳物质的部分熔融;Nb/Ta比值分别为20.87~23.62和4.41~22.90,反映岩浆演化过程存在流体作用;较低的CaO/Na2O(平均值0.34)、Rb/Sr(平均值2.04)和Rb/Ba(平均值0.86)指示来源于贫黏土的变质页岩;与90号脉富锂伟晶岩,509道班西(白龙山)贫锂伟晶岩具有一致的δ7Li值,指示来源于相同的源区;近矿围岩较高的δ7Li值,可能是锂同位素扩散导致。509道班西(白龙山)富锂伟晶岩的δ7Li值明显低于区内花岗岩、贫锂伟晶岩和90号脉富锂伟晶岩,可能与岩浆演化过程中熔体-流体分离、侵入后的冷却速率、扩散驱动等因素有关,岩浆演化晚期熔体-流体分离过程中P、F等挥发分元素对90号富锂伟晶岩脉的形成起关键作用。 |
| 中文关键词:地球化学 花岗岩 伟晶岩 Li同位素 成矿模式 大红柳滩 |
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| Discussion on genetic relationship between granite and pegmatite in Dahongliutan rare metal ore field, Xinjiang |
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| Abstract:The Dahongliutan rare metal ore field in western Kunlun exposes a large area of composite granite body and thousands of granite pegmatite dikes. The Li-poor and Li-rich pegmatite dikes are distributed in the Bayankalashan Group, quartz diorite, biotite monzogranite, as well as the periphery of the two-mica monzogranite and garnet tourmaline two-mica monzogranite (within 2 km). There are obvious mineral assemblage zoning around the composite granite body. The rare metal mineralized pegmatite is more closely related to the two-mica monzogranite and garnet tourmaline two-mica monzogranite in spatial relationship. The field geological characteristics and precise chronological data show that the composite granite body is mainly composed of gneissic quartz diorite, biotite monzogranite and two-mica monzogranite, formed during 214.7~213.7 Ma, 214~213 Ma and 209.6~208.8 Ma respectively. Granite pegmatites mainly formed during 223~207.4 Ma (U-Pb dating of cassiterite, zircon, monazite, and niobium tantalum minerals), which show a close spatial-temporal relationship. Quartz diorite, biotite monzogranite and two-mica monzogranite have different lithogeochemical characteristics, εHf(t), εNd(t), and δ7Li ratio, which mean that they originated from different magma sources. Two-mica monzogranite and garnet tourmaline two-mica monzogranite have similar εHf(t) (-9.49~-4.47) and εNd(t) (-8.64~-7.81) values, which indicates that they derived from partial melting of the lower crust. Nb/Ta ratios are 20.87~23.62 and 4.41~22.90 respectively, displaying evidence of interactions with fluids. The lower ratios of CaO/Na2O (average of 0.34), Rb/Sr (average of 2.04) and Rb/Ba (average of 0.86) indicate that they derived from clay-poor meta-shale. It is consistent with No. 90 Li-rich pegmatite vein and western 509 Daoban (Bailongshan) Li-poor pegmatite δ7Li ratio, indicating that they originated from the same source area. High ratio of δ7Li from country rock near the ore body may be caused by lithium isotope diffusion. The ratio of δ7Li from western 509 Daoban (Bailongshan) Li-rich pegmatite is obviously lower than that of granite, Li-poor pegmatite and No. 90 Li-rich pegmatite vein, which may be related to factors such as melt fluid separation, cooling rate after magma emplacement and diffusion driven during magma evolution. In the process of melt fluid separation in late magma evolution, volatile elements such as P and F play a key role in the formation of No. 90 Li-rich pegmatite vein. |
| keywords:geochemistry granite pegmatite Li isotope metallogenic model Dahongliutan |
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