云南格咱岛弧斑岩-矽卡岩铜、钼(金)矿床成矿系统

The metallogenic system of porphyry-skarn type Cu,Mo(Au) polymetallic deposits in Geza island arc of Yunnan Province

格咱岛弧带是西南三江多岛弧盆系中一个主要的地质构造单元,它始于晚三叠世甘孜—理塘洋壳的向西俯冲,燕山期经历了陆内汇聚和造山后伸展作用阶段,区内岩浆活动和成矿作用强烈,是近年来新发现的重要铜多金属成矿带。根据区内岩浆岩和矿床的时空分布,同位素年代学证据,构造环境及成矿作用,将格咱岛弧成矿系统划分为印支期成矿亚系统和燕山期成矿亚系统。印支期主要发育了与安山岩同源的壳幔型中酸性岩浆作用,形成斑岩型Cu矿成矿系统,燕山期伴随着同碰撞中酸性岩浆活动形成斑岩型Mo(Cu)及热液型W(Mo)成矿系统。研究表明,格咱岛弧深部找矿具有较好的资源潜力,其中燕山期Mo多金属成矿已显现出良好的找矿前景。

Geza island arc belt is one of the important tectonic units in the archipelagic arc-basin system of the Sanjiang Region. it started its evolution at the westward subduction of Ganzi-Litang oceanic crust in Late Triassic, and experienced intracontinental convergence and post-orogenic extensional phase in Yanshanian period. In this region, there were strong magmatic activities and rich mineralization, constituting an important copper polymetallic ore concentration area discovered in recent years. According to temporal and spatial distribution of magmatic rocks and ore deposits, geochronological evidence, tectonic setting and mineralization, the Geza island arc metallogenic system can be divided into Indosinian metaUogenic subsystem and Yanshanian metallogenic subsystem. The Indosinian subsystem mainly developed intermediate-acidic crust-mantle magmatism homologous with the andesite and formed porphyry Cu metallogenic system; the Yanshanian subsystem had syn-collision magrnatic activities leading to the generation of the porphyry Mo （Cu） and W （Mo） hydrothermal metaUogenic system. Studies show that Geza island arc has favorable resource potential in the depth, with Mo polymetallic mineralization of Yanshanian epoch showing better prospect.