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文摘
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湘西—黔东是我国重要的铅锌成矿区,具有类似的成矿地质背景。但是,贵州境内铅锌矿化的规模远不如湘西,何种原因导致这种差异性成矿尚不清楚。本文开展黔东卜口场、嗅脑和克麻铅锌矿床成矿期热液方解石稀土元素(REE)研究,并与区带上(花垣、牛角塘)和国内典型超大型铅锌矿床(会泽、金顶)进行对比,为认识成矿物质来源提供制约。卜口场、嗅脑和克麻矿床方解石具有一致的REE_(SN)配分模式,其ΣREE含量低(1.6×10~(-6)~22.5×10~(-6)),轻、重稀土分异不明显,有弱负Ce异常(δCe_(SN)=0.62~0.81)和正Gd和Y异常(δGd_(SN)=0.78~1.23;δY_(SN)=0.99~1.78),指示成矿流体中的REE主要来源于赋矿围岩寒武系第二统清虚洞组碳酸盐岩。花垣和牛角塘矿床方解石ΣREE含量较高(平均为28×10~(-6)和24×10~(-6)),暗示富REE流体加入或者成矿流体与REE含量高的基底岩石发生过水岩反应。金顶和会泽矿床方解石ΣREE最高(平均为78×10~(-6)和73×10~(-6)),具有正Eu异常(δEu_(SN)平均值为1.11和1.55),指示成矿流体在地壳深部或基底经历过高温水岩作用。综合分析认为,黔东铅锌矿床成矿流体主要来自赋矿的碳酸盐岩地层,而花垣、牛角塘、会泽和金顶铅锌矿床的成矿流体具有多源性或与富REE的基底岩石发生过强烈水岩反应,这可能是超大型-大型铅锌矿床形成的重要诱因。 |
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其他语种文摘
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The western Hunan and eastern Guizhou are significant Pb-Zn metallogenic areas in China with similar geological settings of metallogeny. However, the Pb-Zn deposits in the eastern Guizhou are much smaller in size than those in the western Hunan. It remains unclear about the reasons for this differential mineralization. In this paper, we have carried out a comparative study between REE compositions of ore-stage hydrothermal calcites of the Bokouchang, Xiunao, and Kema deposits in the eastern Guizhou and representative deposits in the same metallogenic belt (Huayuan, Niujiaotang deposits) and some typical super-large Pb-Zn deposits in other areas (Jinding and Huize deposits), to provide a constraint for understating the source of ore-forming materials. Calcites from Bokouchang, Xiunao, and Kema deposits in the eastern Guizhou have similar REE distribution patterns with characteristics of low ΣREE contents (1.6×10~(-6)-22.5×10~(-6)), little differentiation between LREE and HREE, negative Ce anomalies (δCe_(SN)=0.62-0.81), and positive Gd and Y anomalies (δGd_(SN)=0.78-1.23, δY_(SN)=0.99-1.78), indicating that the REE of ore-forming fluids could be mainly sourced from the ore-hosted carbonate of the Lower Cambrian Qingxudong Formation. In contrast, calcites of the Huayuan and Niujiaotang deposits have relatively high ΣREE contents (average 28×10~(-6) and 24×10~(-6)), implying an addition of REE-rich fluids or water-rock interactions between the ore-forming fluid and underlying REE-rich basement. Calcites of the Jinding and Huize deposits have the highest ΣREE contents (average 78×10~(-6) and 73×10~(-6)) and positive Eu anomalies (average δEu_(SN)=1.11 and 1.55), suggesting that the ore-forming fluids had experienced high-temperature water-rock interaction in the deep part of crust or basement. It is concluded that the ore-forming fluids of Pb-Zn deposits in the eastern Guizhou could have dominantly originated from the host rocks of marine carbonates, whereas those of the Huayuan, Niujiaotang, Huize, and Jinding deposits, could be derived from a mixture of variously sourced fluids or strongly interacted with underlying basement rocks. The multi-sourced fluids or strong water-rock reaction between ore-forming fluid and REE-rich basement rocks could be significant causes for the formation of the large and super-large Pb-Zn deposits. |
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来源
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矿物学报
,2020,40(4):356-366 【核心库】
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DOI
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10.16461/j.cnki.1000-4734.2020.40.013
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关键词
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矿床成因
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稀土元素
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方解石
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铅锌矿
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湘西-黔东成矿带
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地址
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1.
中国科学院地球化学研究所, 矿床地球化学国家重点实验室, 贵州, 贵阳, 550081
2.
贵州省有色和核工业地质勘查局一总队, 贵州, 贵阳, 551400
3.
贵州省地矿局地球物理地球化学勘查院, 贵州, 贵阳, 550018
4.
贵州地质调查局, 贵州, 贵阳, 550081
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中国科学院大学, 北京, 100049
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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1000-4734 |
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学科
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地质学 |
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基金
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国家自然科学基金项目
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贵州省项目
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贵州省地矿局项目
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文献收藏号
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CSCD:6778275
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