西南“三江”格咱岛弧斑岩成矿系统

Porphyry metallogenic system of Geza arc in the Sanjiang region, southwestern China

西南"三江"格咱岛弧是"三江"古特提斯演化形成的重要地质构造单元,该单元从晚三叠世洋壳俯冲、洋盆关闭转入碰撞及走滑剪切阶段都产生酸性岩体,形成斑岩Cu-Mo-Au矿床,并构成独立的成矿系统。笔者将格咱岛弧成矿作用以三大岩浆活动期次为基础划分为三套成矿系统,即印支期斑岩Cu多金属成矿系统、燕山期斑岩Mo-Cu多金属成矿系统和喜马拉雅期富碱斑岩Au-Mo-Cu多金属成矿系统。本文从成矿时间、成矿物质来源、成矿流体系统和成矿动力学背景等方面详细总结论述了格咱岛弧的三套斑岩成矿系统。同一地区三大成矿系统反映三次地质构造事件,这种构造演化的连续性和成矿对应性使得该带的研究具有重要意义。

Gaza arc is an important tectonic unit formed by evolution of Tethys in the Sanjiang region, Southwest China. The island arc has complex tectonic structures, strong magmatisms, active ore forming fluids, complicated and multiple metallogenics which formed a number of large-super large scale deposits with complete deposit types. Pervasive traces of multi-episode tectonic-magmatic-hydrothermal activities make the island arc a natural laboratory for studies of tectonic evolution and multi-episode metallogenics since Tethys period in the Sanjiang region. Based on discoveries of large-super large scale deposits in this area and achievements on systematic studies of magmatisms and metallogenics since Indosinian, the authors divided the Gaza island arc metallogenics into three metallogenic systems based on three-stage magmatisms： Indosinian porphyry Cu-polymetallic metallogenic system, Yanshanian porphyry Mo-Cu-polymetallic metallogenic system and Himalayan alkali-rich porphyry Au-Mo-Cu polymetallic metallogenic system. This paper discussed and concluded the mineralization ages, source of ore-forming materials, ore-forming fluid systems and metallogenic dynamics backgrounds of the three-stage porphyry metallogenic systems of Gaza island metallogenic system.