| 贵州泥堡卡林型金矿热液蚀变矿物学研究及其地质意义 |
| Received:July 12, 2017 Revised:November 25, 2017 点此下载全文 |
| 引用本文：CHEN MaoHong,GUO ShenXiang,XIE XianYang,MA KeZhong.2018.Hydrothermal mineralogy of Nibao Carlin-type gold deposit, Guizhou Province and its geological significances[J].Mineral Deposits,37(3):502~520 |
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| Author Name | Affiliation | | CHEN MaoHong | MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China | | GUO ShenXiang | School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China | | XIE XianYang | MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China | | MA KeZhong | MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China |
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| 基金项目:本文受国家自然科学基金面上项目（编号：41572072）、国家重点基础研究发展计划"973"课题（编号：2014CB440902）和中国地质调查局地调项目（编号：DD20160124）联合资助 |
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| 中文摘要:贵州泥堡卡林型金矿床是黔西南碳酸盐岩台地相区新发现的大型矿床，主要赋矿围岩为上二叠统峨眉山玄武岩组含钙质的玄武质沉火山角砾凝灰岩。因此，泥堡金矿一方面具有一般卡林型金矿的低温矿物组合和载金矿物特点，另一方面由于赋矿围岩的特殊性，还出现一些特征性的热液蚀变矿物。泥堡金矿主要载金矿物为环带状含砷黄铁矿和毒砂，其中黄铁矿可以分为6种类型：草莓状黄铁矿（Py0）为沉积成因，环带状黄铁矿核部的暗色麻点状黄铁矿（PyⅠ）为被热液改造的沉积成因，二者均以低w（As）为特点；环带状黄铁矿的内环（PyⅡ）为热液早期形成的黄铁矿，中间环带（PyⅢ）或者外环（PyⅣ）是热液活动高峰时期形成的含砷黄铁矿，具有典型的高As低S、Fe特点，是主要的含金部位。成矿晚阶段形成的黄铁矿（PyⅤ）与辉锑矿、闪锌矿共生。成矿过程中强烈的水岩交代作用下，峨眉山玄武岩组火山岩中的Ti、P、Cu等元素析出，在矿体中形成较多的锐钛矿、磷灰石、黄铜矿、黝铜矿等特征蚀变矿物。激光拉曼测试表明在低温成矿条件下形成的TiO2矿物是锐钛矿而不是金红石，因此前人获得的金红石年龄能否代表金的成矿年龄值得商榷。相反，磷灰石、绢云母是主成矿阶段形成的新生热液矿物，其原位测年数据可大致代表金的成矿年龄，因此二者是较为合适的测年对象。成矿晚阶段出现重晶石和石膏等硫酸盐矿物，说明成矿环境更为氧化，同时由于同位素分馏，导致了与硫酸盐共生的硫化物如辉锑矿、雌黄和雄黄的δ34S值相比主成矿阶段的黄铁矿和毒砂更低。热液蚀变矿物学是探讨成矿作用过程的重要基础，在卡林型金矿研究中尤为重要。 |
| 中文关键词:地质学 特征热液蚀变矿物 环带状黄铁矿 磷灰石 泥堡金矿 |
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| Hydrothermal mineralogy of Nibao Carlin-type gold deposit, Guizhou Province and its geological significances |
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| Abstract:The Nibao gold deposit is a large Carlin-type fault-controlled deposit located in southwestern Guizhou Province of China. The wall rock of the deposit is mainly calcareous-bearing pyroclastic breccias from upper Permian Emeishan Basaltic Formation. Therefore, this deposit is characterized with common low temperature mineral assemblages and Au-bearing minerals of Carlin -type deposits, and some unique hydrothermal minerals. The zoned arsenian pyrite and arsenopyrite are the dominant Au-bearing minerals, and progress from early sedimentary framboidal pyrite (Py 0) and hydrothermally altered dark-pitted sedimentary pyrite (Py I) with low As content, which is overgrown by hydrothermal pyrite (Py Ⅱ). These pyrites are in turn overgrown by auriferous middle (Py Ⅲ) and outer (Py IV) zones of arsenian pyrite with relatively high As and low S and Fe contents. The last generation of pyrite (Py V) is associated with stibnite and sphalerite. The elements Ti, P, Cu were derived from the volcanic host-rocks of the Emeishan Basalt Formation and precipitated into minerals such as anatase, apatite, chalcopyrite, tetrahedrite during hydrothermal alteration. Laser Raman spectroscopy studies show the TiO2-bearing mineral that formed in the low temperature condition is anatase rather than rutile. Thus, whether or not the obtained age of rutile by previous researcher could represent the ore-forming age of gold need further study. Contrarily, apatite and sericite are hydrothermal minerals that formed during the main metallogenic stage, and their in-situ dating data could represent the ore-forming age of the Nibao gold deposit. Sulfate minerals such as barite, and gypsum formed in the late stage of the ore-forming process are indicators of a more oxidised setting. Furthermore, isotopic fractionation has resulted in sulfides, such as stibnite, orpiment and realgar, which are co-existed with sulfate minerals, having lower sulfur isotopic compositions than the ore-stage pyrite and arsenopyrite. This study shows that hydrothermal mineralogical studies are important in understanding the mineralization processes related to Carlin-type gold deposits. |
| keywords:geology characteristic hydrothermal mineral zoned pyrite apatite Nibao gold deposit |
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