投稿时间：2023-09-11
修订日期：2023-11-20
网络发布日期：2024-03-08
中文摘要:瑶岗仙钨矿是南岭地区唯一一个石英脉型黑钨矿和矽卡岩型白钨矿均达大型规模的超大型矿床。两类钨矿体均产出于瑶岗仙复式花岗岩体的内外接触带，复式花岗岩体主要由中粒黑云母花岗岩和细粒二云母花岗岩组成，但多阶段岩浆演化与两类钨矿化关系问题一直存在较大争议。文章以瑶岗仙矿区中粒黑云母二长花岗岩与细粒二云母二长花岗岩中的黑云母和石榴子石为切入点，对比研究两阶段花岗质岩浆氧逸度、挥发分、结晶分异程度，探讨了岩浆演化对钨矿化成因的制约。结果显示，细粒二云母二长花岗岩相较于中粒黑云母二长花岗岩中黑云母拥有更低的XMg值、更靠近Fe2+端员、更低的Ⅳ（F）和更高的log（fHF/fHCl）fluid值，指示其形成于还原性岩浆环境，且F含量更高，而后者更偏向氧化性，F含量偏低。两类花岗岩中的石榴子石均为岩浆成因的锰铝榴石，从中粒黑云母花岗岩至细粒二云母花岗岩，随着石榴子石中MnO含量的递增，CaO、FeO、MgO含量逐渐降低，Mn/（Mn+Fe）比值、Sc、Zn、Y、HREE含量随MgO降低而逐渐升高，表明细粒二云母二长花岗岩较中粒黑云母二长花岗岩演化程度更高，更有利于W的富集。石英脉型黑钨矿和矽卡岩型白钨矿成矿岩浆均具有低氧逸度和高F含量的特征，与细粒二云母二长花岗岩成岩环境一致。基于上述研究，结合矿区地球物理、地球化学、钻探信息，笔者建立了瑶岗仙矿床深部勘查模型，圈定了大根垄深部石英脉型黑钨矿找矿靶区、杨梅岭深部云英岩型找矿靶区、和尚滩南东侧矽卡岩型白钨矿找矿靶区。
Abstract:The Yaogangxian W deposit in the Nanling region hosts quartz vein-type wolframite orebody and skarn-type scheelite orebody, which both reach large scale sizes and together to make this deposit to be one of the largest W deposits around the world. Both quartz-vein- and skarn-type orebodies occur in the contact zones between the Yaogangxian granitic complex and the country rocks. The Yaogangxian complex massif mainly consists of medium-grained biotite monzogranite and fine-grained two-mica monzogranite, but the genetic relationship between multi-stage magmatic evolution and different types of tungsten mineralization has been debated intensively. In this study, we examined the geochemical characteristics of biotite and garnet from the medium-grained biotite monzogranite and fine-grained two-mica monzogranite, in order to figure out chemical conditions during the formation of different granitic phases. Biotite from the fine-grained two-mica monzogranite has lower XMg value, closer to Fe2+ end members, lower Ⅳ(F) and higher log(fHF/fHCl)fluid value than that from the medium-grained biotite monzogranite, indicating that the former formed in more reduced environment with higher F contents compared to the latter. Garnet from both phases are typical magmatic origin, and are in spessartite compositions. MnO contents in garnet grains increase with the decrease of CaO, FeO, and MgO contents, and Mn/(Mn+Fe) values, and Sc, Zn, Y, and HREE concentrations gradually increase with the decrease of MgO contents from medium-grained biotite monzogranite to fine-grained two-mica monzogranite, suggesting that the magmatic differentiation of fine-grained two-mica monzogranite is higher than that of medium-grained biotite monzogranite, which is conducive to the enrichment of W. The formation of quartz vein-type wolframite and skarn-type scheelite ores are proposed to be characterised by low oxygen fugacity and high F content, which is consistent with that of the fine-grained two-mica monzogranite. Accordingly, in combination of the geophysical, geochemical, and drilling information, we propose the exploration model for the deep part of the Yaogangxian deposit, and define quartz vein-type wolframite prospecting target in the deep Dagenlong area, greisen-type W prospecting target in the deep Yanmeiling area, and skarn-type scheelite prospecting target in the southeast of the Heshangtan area.
keywords:biotite garnet oxygen fugacity volatiles fractional crystallization exploration model Yaogangxian W deposit
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基金项目:本文得到国家自然科学基金地质联合基金重点项目（编号：U2344207）、国家重点研发计划项目（编号：2022YFC2905101）、国家自然科学基金（编号：41973046）、中国地质调查局地质调查项目（编号：DD20190713）联合资助
引用文本：
郭聪,赵正,刘战庆,吴小辉,刘洋.2024.瑶岗仙花岗质岩浆演化与两类钨矿化成因关系研究：黑云母和石榴子石矿物化学证据[J].矿床地质,43(1):102~127GUO Cong,ZHAO Zheng,LIU ZhanQing,WU XiaoHui,LIU Yang.2024.Genesis relationship between magma evolution and two types of tungsten mine-ralization in Yaogangxian deposit: Evidence from biotite and garnet chemistry[J].Mineral Deposits43(1):102~127
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