滇西普朗斑岩型铜矿床成因及控矿因素

Ore-controlling Factors and Genesis of Pulang Porphyry Copper Deposit in West Yunnan Province

滇西香格里拉地区普朗铜矿床为全球范围内少有的具有还原性特征的斑岩矿床,其规模远大于区内氧化性矿床。该矿床成因究竟是属于氧化性矿床还是还原性矿床,当前学术界仍存在不同的认识。为进一步厘定矿床成因类型,结合区域成矿地质背景,以香格里拉地区的找矿勘查成果为基础,深入分析了普朗铜矿床地质特征、成矿岩体地球化学特征、成矿流体和矿物组合特征,并对控矿因素进行了讨论。研究表明:(1)普朗矿床中的成矿岩体(石英二长斑岩)为氧化性岩体,成矿流体中发育有含CH4的流体包裹体,矿区磁黄铁矿广泛发育;(2)普朗铜矿为具有还原性特征的氧化性斑岩矿床,其形成是因后期有天水携带地层中的有机质通过以NW向黑水塘断裂为主的构造裂隙加入岩浆流体,使得成矿物质得以有效还原、沉淀;(3)高氧逸度岩体(石英二长斑岩)及有利的构造条件严格控制了矿床的成矿作用,石英二长斑岩及断裂构造可作为矿区找矿勘查的重要标志,香格里拉地区浪都、亚杂、卓玛、欠虽以及烂泥塘等地均具有一定的找矿潜力。

Pulang copper deposit is located in Shangri-La District,West Yunnan Province. It is one of the rare porphyry deposits which has reductive characteristics all over the world. The scale of Pulang copper deposit is far larger than the one of the deposits with oxidative characteristics in Shangri-La District. At present,there is still a different understanding that is the deposit genesis is belongs to oxidative one or reductive one in academia. In order to determine the genetic types of Pulang cop-per deposit,based on the geological and prospecting results of Shangri-La District,the regional metallogenic geological back-ground is discussed,the deposit geological characteristics,geochemical characteristics of metallogenic rock mass,characteristics of metallogenic fluid and mineral composition of Pulang copper deposit are studied in depth,besides that,the ore-controlling factors of the deposit is also analyzed. The study results show that：①the metallogenic rock mass of Pulang copper deposit is ox-idized rock mass,the fluid inclusions which contains CH4 is developed in metallogenic fluid,and the pyrrhotite is widely devel-oped in the mining area;②the genesis of Pulang copper deposit is belongs to the oxididative deposit with reductive characteris-tics,it is due to the organic matters of the stratum carried by meteoric water is added to the structural fractures mainly for NW trending Heishuitang fault in the later period,therefore,the metallogenic materials is reduced and precipitated;③the metallo-genic activities of Pulang copper deposit is controlled strictly by the rock mass with high oxygen fugacity （ quartz monzonite porphyry） and favorable structural conditions,thus the quartz monzonite porphyry and fracture structure can be taken as the fa-vorable prospecting indicators of the mining area,besides that,the prospecting potential of Langdu,Yaza,Zhuoma,Qiansui and Langnitang Area in Shangri-La District is good.