| 新疆火烧云超大型非硫化物铅锌矿床:发生表生氧化的密西西比河谷型矿床 |
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| 引用本文： | 吴志旖,宋玉财,侯增谦,刘英超,庄亮亮.新疆火烧云超大型非硫化物铅锌矿床:发生表生氧化的密西西比河谷型矿床[J].地球科学,2019,44(6):1987-1997. |
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| 作者姓名： | 吴志旖 宋玉财 侯增谦 刘英超 庄亮亮 |
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| 作者单位： | 1.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： | 国家重点研发计划项目2016YFC0600306国家自然科学基金项目41773043国家自然科学基金项目41320104004国家自然科学基金项目41773042国家自然科学基金项目41772088国家自然科学基金项目91855214国土资源大调查项目DD20160024-02 |
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| 摘 要： | 火烧云矿床是我国新发现具有超大型规模的非硫化物铅锌矿床，成因倍受关注.矿床主要由菱锌矿和白铅矿组成，形成块状及少量纹层状和角砾状矿石，构成了层状矿体.赋矿围岩为中侏罗统含沉积石膏的台地相碳酸盐岩，为密西西比河谷型矿床的典型赋矿围岩，而非喷流沉积型矿床的赋矿围岩.矿石中普遍出现被白铅矿交代的方铅矿残留，表明原生矿化为硫化物.方铅矿δ34SV-CDT值为-34‰~-18‰，显示还原硫的来源与细菌还原作用作用有关，这在MVT矿床中较为常见，而在与岩浆作用有关的铅锌矿床中少见.同时，矿床也不具有与岩浆有关的热液矿化和蚀变特征，故矿床的原生硫化物矿化应为MVT型.通过菱锌矿和白铅矿的O同位素组成，计算出形成这两种矿物的流体具有低温、低δ18O值的大气降水的特征，结合白铅矿交代方铅矿的这一现象，表明目前观察到的由菱锌矿和白铅矿构成铅锌矿体系是在表生作用下直接交代原生硫化物矿体形成.
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| 关 键 词： | 菱锌矿 白铅矿 方铅矿 台地碳酸盐岩 密西西比河谷型 表生氧化 火烧云 矿床 |
| 收稿时间： | 2018-08-28 |
The World-Class Huoshaoyun Nonsulfide Zinc-Lead Deposit,Xinjiang, NW China: Formation by Supergene Oxidization of a Mississippi Valley-Type Deposit |
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| Abstract: | Huoshaoyun is a newly discovered world-class nonsulfide zinc-lead deposit in Xinjiang, NW China, so its genesis attracts many geologists'attentions. Conformable orebodies in the deposit contain massive and minor stratiform and breccia-hosted ores that are dominated by smithsonite and cerussite. Ores are hosted by Middle Jurassic sedimentary gypsum-bearing platform facies carbonate. Clearly, the carbonate is typical host for Mississippi Valley-type (MVT) deposit rather than for sedimentary exhalative (SEDEX) deposit. Galena is common in the ores and was replaced by cerussite, implying that precursor mineralization in the deposit was zinc and lead sulfides. δ34SV-CDT values of the galena range from -34‰ to -18‰, indicating that derivation of reduced sulfur was related to bacterial sulfate reduction (BSR) process, which is common in MVT deposits but is scarce in magmatic -related Zn -Pb deposits. Together with the absence of magmatic -related hydrothermal alteration and mineralization, it suggests that primary mineralization at Huoshaoyun is of MVT origin. Oxygen isotopic compositions of water that reached isotopic equilibrium with smithsonite and cerussite are low in temperature and light in δ18O values, implyimg that meteoric water was involved in the two mineral formations. Combined with the observation that galena was replaced by cerussite, we suggest that the smithsonite and cerussite were the result of intensive supergene oxidization of primary znic and lead sulfides of MVT origin. |
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