摘要
西藏多龙矿集区是近年来中国新发现的具有世界级潜力的铜金矿集区。该矿集区现已查明多不杂、波龙、拿若和铁格隆南4个大型-超大型矿床,并新发现地堡那木岗和拿顿矿点。文章对上述矿床(点)脉体、蚀变、矿化和流体特征开展了系统研究和对比。结果表明,多不杂、波龙和拿若矿床矿化类型以斑岩型为主,同时钾硅酸盐化、绢英岩化、青磐岩化等蚀变广泛发育,而铁格隆南矿床除上述蚀变类型外,还叠加有高级泥化蚀变,并发育与之相关的浅成低温热液型矿化。根据脉体特征对比和流体包裹体温压计算推测,上述4个矿床矿化类型的差异可能由剥蚀深度的差异所引起(前三者剥蚀深度约为2~3 km,后者约为1~1.5 km)。此外,地堡那木岗矿点蚀变类型以绢英岩化、泥化为主,该矿点发育与斑岩型金矿中类似的深色条带状石英脉,指示该地区可能存在斑岩型金矿。拿顿矿点为典型的高硫型浅成低温热液型矿化,铜金矿体赋存于角砾岩筒中。野外地质调查表明,上述矿点地表蚀变岩盖(Lithocaps)发育,并且蚀变岩盖空间分布位置与下伏铜金矿体表现出良好的匹配关系,可有效地指导找矿勘查工作。流体包裹体实验进一步表明,铜金元素在斑岩型矿化中的沉淀可能与温度降低和氧逸度的变化有关,而在浅成低温热液型矿化中的沉淀则受控于温度的降低和流体的不混溶作用。最后,在前人年代学研究基础上,结合本次实验结果构建了该地区与成矿作用有关的时空演化模型。
The Duolong Cu-Au ore concentration area, located in central Tibet, is an emerging world-class metallogenic area in China. This area comprises four major deposits(Duobuza, Bolong, Naruo, and Tiegelongnan), and two ore spots(Dibaonamugang and Nadun). This paper presents systematic comparison and analyses with respect to vein formation, alteration, mineralization, and ore-forming fluids. Field investigation shows that Duobuza, Bolong,and Naruo deposits are porphyry-style deposits characterized by widespread potassic, sericitic, and propylitic alteration, meanwhile the Tiegelongnan deposit is overprinted by advanced argillic alteration in addition to all these hydrothermal alteration mentioned above with corresponding epithermal-style mineralization. Based on comparison of vein formation and calculation of fluid inclusions, the difference of mineralization style was likely caused by depth of erosion(2~3 km for the first three, 1~1.5 km for the last one). Additionally, the Dibaonamugang ore spot is dominated by sericitic and argillic alteration, and characterized by quartz with banded form,which is similar to the diagnostic features of gold porphyry deposits. The Nadun ore spot is a typical high-sulfidation epithermal mineralization hosted in a breccia system. Field investigation also reveals that lithocaps are correlated with underlying Cu-Au mineralization spatially, which should be taken into account for future exploration.Fluid inclusion reveals that ore precipitation was mainly caused by cooling of ore-forming fluids coupled with variation of oxidation stage, whereas constant cooling of ore-forming fluids and fluid mixing were the major factors for epithermal mineralization. Lastly, this paper reconstructs the temporal and spatial evolution history of CuAu ore formation of the Duolong ore concentration area based on analytical data from this paper and previous published dating results.
作者
孙嘉
毛景文
林彬
姚佛军
李玉彬
贺文
刘泽群
SUN Jia;MAO JingWen;LIN Bin;YAO FuJun;LI YuBin;HE Wen;LIU ZeQun(MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Geological Survey of Tibet, Lhasa 850000, Tibet, China;School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;Beijing Geological and Mineral Exploration and Development Co., Ltd., Beijing 100085, China)
出处
《矿床地质》
CAS
CSCD
北大核心
2019年第5期1159-1184,共26页
Mineral Deposits
基金
国家重点研发计划项目（编号：2017YFC0601403）
中国地质调查局地质调查工作项目（编号：1212011120994）
中央级科研院所基本业务费项目（编号：K1501）联合资助
关键词
地质学
矿化特征
斑岩矿床
浅成低温热液矿床
多龙矿集区
西藏
geology
mineralization characteristics
porphyry deposit
epithermal deposit
Duolong ore concentration area
Tibet
