| 西藏谢通门县雄村斑岩型铜金矿集区Ⅰ号矿体的蚀变与矿化特征 |
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| 引用本文：郎兴海,唐菊兴,李志军,黄勇,陈渊,张丽.2011.Alteration and mineralization of No.Ⅰ ore body in Xiongcun porphyry copper-gold metallogenic ore district, Xietongmen County, Tibet[J].Mineral Deposits,30(2):327~338 |
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| 基金项目:本文为国家科技支撑项目（编号: 2006BAB01A01）、天圆公司项目、青藏专项（编号: 1212010818089）、国家基础研究计划“印度-亚洲大陆主碰撞带成矿作用”973项目(编号： 2002CB412607)资助的成果 |
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| 中文摘要:雄村斑岩型铜金矿集区位于西藏冈底斯成矿带，是目前该带上发现的唯一一个与新特提斯洋壳早期俯冲作用有关的斑岩型铜金矿区，由Ⅰ、Ⅱ、Ⅲ号铜金矿体组成。雄村Ⅰ号铜金矿体具有规模大、蚀变强烈、富金银而贫钼的特点，其蚀变-矿化系统受中-晚侏罗世侵入于雄村组凝灰岩中的多个含眼球状石英斑晶的角闪石英闪长玢岩岩枝的控制，矿体即赋存于玢岩岩枝及其接触带附近的凝灰岩中。通过对雄村Ⅰ号铜金矿体蚀变和矿化特征的研究可以得出以下几点认识：①Ⅰ号铜金矿体的热液蚀变作用可分为早、晚2期，早期蚀变经历了弱的钾硅酸盐化阶段和强烈红柱石次生石英岩化阶段，晚期蚀变经历了黄铁绢英岩化阶段和青磐岩化阶段，晚期蚀变叠加于早期蚀变之上。由斑岩体中心向外，蚀变分带依次可划分为强硅化带→红柱石次生石英岩化带→绢英岩化带→青磐岩化带。主要赋矿蚀变带为强硅化带和红柱石次生石英岩化带。②Ⅰ号铜金矿体的矿化主要呈浸染状、脉状或网脉状。由斑岩体中心向外，矿化分带依次为黄铁矿-黄铜矿-（磁黄铁矿）→黄铁矿-磁黄铁矿-（黄铜矿）→黄铁矿→闪锌矿，主要含矿脉的分布依次为石英-硫化物脉→石英-红柱石-黑云母(白云母)-硫化物脉→黄铁矿脉→多金属硫化物脉，主要赋矿脉为石英-硫化物脉和石英-红柱石-黑云母(白云母)-硫化物脉。③Ⅰ号铜金矿体弱的钾硅酸盐化蚀变和强烈的红柱石次生石英岩化蚀变暗示成矿流体具有较低的K+/H+值。在斑岩蚀变系统形成早期，矿床经历了高温阶段，形成弱的钾硅酸盐化蚀变，之后，斑岩蚀变系统迅速降温，形成大规模的红柱石次生石英岩化蚀变，斑岩蚀变系统的早期迅速降温可能是由于岩体的上侵导致表层岩石引张而产生断裂破碎，使得大气降水能快速的进入斑岩蚀变系统而造成的。 |
| 中文关键词:地质学 雄村 斑岩型铜金矿床 蚀变 矿化 红柱石 |
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| Alteration and mineralization of No.Ⅰ ore body in Xiongcun porphyry copper-gold metallogenic ore district, Xietongmen County, Tibet |
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| Abstract:The Xiongcun porphyry copper-gold metallogenic district, located in the Gangdise metallogenic belt, is the only copper-gold metallogenic ore district related to early subduction activity of Neotethys oceanic crust. It is composed of No.Ⅰ, No.Ⅱ and No. Ⅲ ore bodies. In this paper, the Xiongcun No.Ⅰ ore body was chosen as the research object. This ore body has the characteristics of large size, strong alteration, poor molybdenite and rich gold. The lteration-mineralization system is controlled by several middle-late Jurassic quartz diorite porphyry with big quartz eyes which intruded into tuff of Xiongcun Formation. The Xiongcun No.Ⅰ ore body lies in the quartz diorite porphyry with big quartz eyes and the tuff. Based on a study of its alteration and mineralization, the authors have reached the following conclusions: ① The alteration of the Xiongcun No.Ⅰ ore body occurred at two stages (early stage and late stage). The early stage included poorly developed potassic alteration and well developed andalusite-silicification, whereas the late stage included phyllic alteration and propylitic alteration, with the late stage superimposed upon the early stage. From the core of the porphyry, the alteration zoning is in order of strong silicification zone → andalusite-silicification zone → phyllic zone → propylitic zone. The main mineralization zone is composed of strong silicification zone and andalusite-silicification zone. ② Mineralization of the Xiongcun No.Ⅰ ore body find expression in dissemination-veins or stockworks. From the core of the porphyry, the mineralization zoning is in order of pyrite-chalcopyrite-(pyrrhotite)→pyrite-pyrrhotite-(chalcopyrite)→pyrite→sphalerite, and the mineralization veins zoning is in order of quartz-sulfide vein→quartz-andalusite-biotite±muscovite-sulfide vein→pyrite vein→polymetallic sulfide vein. The main mineralization veins are quartz-sulfide vein and quartz-andalusite-biotite±muscovite_sulfide vein. After the formation of the ore deposit, it experienced weak supergenic alteration and formed the oxidized zone and supergene sulfide zone, but the main ore body is located in the hypogene sulfide zone. ③ The presence of poorly-developed potassic alteration and well developed andalusite-silicification alteration implies that the fluids were characterized by relatively low K+/H- ratio and experienced a period of high temperature and formed poorly-developed potassic alteration, and then the fluids entered into a stage of slightly lower temperature and formed well developed andalusite silicification. The lower temperature might have resulted from the involvement of cooler meteoric waters in the alteration system. |
| keywords:geology, Xiongcun, porphyry copper-gold deposit, alteration, mineralization, andalusite |
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