| 内蒙古维拉斯托-拜仁达坝矿床矿石特征及成矿机理 |
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| 引用本文： | 唐然坤,吕新彪,曹晓峰,梅 微,尚世超,吴建亮,艾智龙.内蒙古维拉斯托-拜仁达坝矿床矿石特征及成矿机理[J].地球科学,2014,39(6):671-686. |
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| 作者姓名： | 唐然坤 吕新彪 曹晓峰 梅 微 尚世超 吴建亮 艾智龙 |
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| 作者单位： | 1.中国地质大学资源学院，湖北武汉 430074 |
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| 基金项目： | 内蒙古基金中心矿调项目(No.NMKD2010-3) |
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| 摘 要： | 维拉斯托-拜仁达坝锌铜多金属矿床为近几年大兴安岭中南段西坡发现的较大的2个银多金属矿床，主要对2个矿床矿石矿物组合分析和对比，对主要的矿石矿物组合进行扫描电子显微镜-能谱分析和电子探针分析显示:从早期到晚期，矿物组合从高温钨酸盐和氧化物-复硫化物-硫化物-低温含锑硫盐矿物(锑化物)；银的赋存状态主要为可见银矿物，其次为晶格银(类质同象)和次显微包裹银，其中生成顺序依次为含银黝铜矿+银锑黝铜矿+黝锑银矿-辉锑铅银矿+柱硫锑铅银矿+深红银矿+锑银矿.根据不同成矿阶段的矿物组合和流体包裹体特征得出:成矿早期在氧化偏酸性环境下，W、Sn等以钨酸、钨酸盐等形式迁移，Zn2+、Pb2+、Cu+等金属离子以氯络合物形式迁移；随着黑钨矿气化沉淀及成矿流体物理化学条件的变化，成矿中-晚期成矿环境变为弱碱性还原条件，成矿流体中金属离子以硫氢络合物迁移为主，伴着温度降低和围岩的水-岩作用，硫氢络合物分解，导致磁黄铁矿等硫化物、硫锑银矿物、硫锑铅矿等依次沉淀.
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| 关 键 词： | 维拉斯托-拜仁达坝 银的赋存状态 成矿机理 成矿端员 矿床 矿物学 |
| 收稿时间： | 2013-10-25 |
Mineralogy and Metallogenic Mechanism of Weilasituo and Bairendaba Deposits,Inner Mongolia,China |
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| Abstract: | Weilasituo and Bairendaba are two large-scale silver polymetallic deposits, discovered in the western slope of the south and central sections of Great Hinggan Mountains in recent years. This study focuses on identifying and analyzing the mineral associations and occurrence of silver minerals using scanning electron microscopy-energy dispersive spectrometry and electron microprobe. The analyses suggest that mineral associations change from tungstate and oxide, to diatomic sulphide, to simple sulphide, to antimony sulfosalt mineral, to antimonide with decreasing temperature based on the microscopy observations. The silvers contained in the ore occur in several forms, including mainly visible silver minerals, followed by the lattice silver (isomorphous substitution) and sub-micron inclusion silver. The mineral sequence of visible silver's formation is Ag-bearing tetrahedrite-argentian tetrahedrite-freibergite-diaphorite-freieslebenite-pyrargyrite-dyscrasite. Ag occurs in lattice of chalcopyrite, bornite, chalcocite, pyrite and galena in isomorphism in small amount, and also as the microscopic wrappage in galena. The results, combined with the characteristics of mineral association and fluid inclusions in different mineralizing stages, indicate that W and Sn are transported as wolframic acid and tungstate at the early high-temperature meta-acid oxidizing environment, while Zn2+, Pb2+, Cu+ and other metalions are transported as chloride complexes. After wolframite's precipitation and the changes of metallogenetic fluid physical and chemical condition, the metallogenetic environment becomes slightly alkaline and reductive, and Zn2+, Cu+ and other metalions form HS- complexes. The continuous drop of temperature and water-rock interaction lead to the separation of Zn2+, Cu+ with HS- to form pyrrhotite, sphalerite etc.. In late phases, Ag+ can combine Sb3+, Cu+, Pb2+, Sb3-, S2- etc., which results in multiple silver antimony sulfide minerals, boulangerite etc.. |
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