太行山北段岭东-不老台金多金属矿床地质特征和成因类型

Geology and genesis of Lingdong-Bulaotai gold polymetallic deposit in northern Taihang Mountains, North China

中文关键词:矿床成因  金的赋存状态  岭东-不老台金矿床  中硫型浅成低温热液矿床  太行山北段

keywords:ore genesis  occurrence state of gold  intermediate-sulfidation epithermal deposit  Lingdong-Bulaotai gold deposit  northern Taihang Mountains

中文摘要:近年来太行山北段取得了金多金属矿床的重要找矿突破，相继发现了义兴寨超大型金矿床和岭东-不老台金多金属矿床，后者因矿床成因类型存在争议而制约了下一步找矿工作部署。为此，文章针对岭东-不老台矿床开展了野外调查、矿物学和地球化学的研究，旨在厘定金的赋存状态，限定成矿流体性质，探讨矿床成因类型。文章在矿区识别出5类蚀变矿物组合：石英-多硅白云母-碳酸盐、蒙脱石-碳酸盐、石英-白云母-碳酸盐、绿泥石-白云母±碳酸盐±绿帘石和伊利石-蒙脱石-碳酸盐±绿泥石，其中与成矿关系密切的蚀变矿物组合是石英-多硅白云母/白云母-碳酸盐和伊利石-蒙脱石-碳酸盐±绿泥石。文章发现金矿物主要以自然金和Au-Ag-Te矿物组合为特征，矿石具有中等硫化物含量(5%~20%)，并出现特征性的贫铁闪锌矿w(FeS)=0.58%~2.92%和富锰碳酸盐w(MnO)=0.33%~2.11%矿物组合。根据矿物组合推测成矿流体具有低温(250 ℃)、中酸性、低氧逸度、中等硫逸度和较高碲逸度的特征。综上，文章提出岭东-不老台矿床可能为太行山北段首例中硫型浅成低温热液矿床，为找矿开拓了新的方向。

Abstract:Important breakthroughs in the prospecting of gold polymetallic deposits have recently been achieved in the northern part of the Taihang Mountains, with the successive discovery of the giant Yixingzhai gold deposit and the Lingdong-Bulaotai gold polymetallic deposit. However, the latter has limited further exploration due to debates about its genetic type. To address this, this study conducts field investigations, mineralogical, and geochemical analyses on the Lingdong-Bulaotai deposit, aiming to clarify the occurrence state of gold, define the properties of ore-forming fluids, and discuss the genetic type of the deposit. Five types of alteration mineral assemblages are identified in the deposit area: quartz-phengite-carbonate, montmorillonite-carbonate, quartz-muscovite-carbonate, chlorite-muscovite±carbonate±epidote, and illite-montmorillonite-carbonate±chlorite. Among these, the alteration mineral assemblages closely related to mineralization are quartz-phengite/muscovite-carbonate and illite-montmorillonite-carbonate±chlorite. Gold minerals primarily include native gold and Au-Ag-Te mineral associations. The ores contain an intermediate sulfide content (5%~20%), and are accompanied by the characteristic mineral assemblages of Fe-poor sphalerite w(FeS)=0.58%~2.92% and manganese-rich carbonate w(MnO)=0.33%~2.11%. Based on these mineral assemblages, the ore-forming fluids are inferred to have the following characteristics: low temperature (250℃), moderately acidic, low oxygen fugacity, intermediate sulfur fugacity, and relatively high tellurium fugacity. In conclusion, this study suggests that the Lingdong-Bulaotai deposit might be the first intermediate sulfidation epithermal deposit in northern section of the Taihang Mountains, which opens up a new direction for prospecting in this area.