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

Abstract：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 metallogenic 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 magmatic activities leading to the generation of the porphyry Mo (Cu) and W (Mo) hydrothermal metallogenic system. Studies show that Geza island arc has favorable resource potential in the depth, with Mo polymetallic mineralization of Yanshanian epoch showing better prospect.