云南省马厂箐Cu-Mo-Au多金属矿集区成矿系统

马厂箐地区是滇西成矿带内一个典型的与喜马拉雅期富碱侵入岩有关的斑岩型铜-钼-金多金属矿集区,发育有斑岩型钼铜、接触交代型铜钼(金)和热液脉型金银铅锌等多种类型矿化。其矿化和蚀变类型及成矿元素组合,在空间上具有明显的以岩体为中心的分带性;岩浆活动与铜钼金成矿作用具有同时性。这3种矿化类型的形成受控于马厂箐斑岩岩浆系统,该岩浆系统提供了成矿的物质、流体和动力。文章在分析成矿证据的基础上,通过对成矿系统结构的剖析,认为正是马厂箐岩体所提供的热动力条件促使从岩浆体中分异出来的成矿流体由岩体向外运移,随着岩体内构造裂隙、接触带构造以及围岩中破碎带等成矿物理化学条件的改变,在不同的边界条件下发生了不同性质的成矿作用,形成了不同的蚀变和矿化类型及成矿元素组合,总体显示出,随着热液成矿作用的进行,矿化由斑岩体向接触带和围岩推进,成矿由高温向低温的演化趋势。马厂箐铜-钼-金多金属矿集区成矿系统的建立,将对滇西成矿带内其他矿集区的成矿理论研究和找矿勘查实践具有借鉴和指导意义。

Metallogenic system of Machangqing Cu-Mo-Au polymetallic ore concentration area in Yunnan Province

As a typical porphyry Cu-Mo-Au ore concentration area related to alkaline-rich intrusive rocks in western Yunnan ore belt, Machangqing has many mineralization types such as porphyry Cu-Mo mineralization, contact metasomatic Cu-Mo-Au mineralization and hydrothermal Au-Ag-Pb-Zn lodes. Alteration-mineralization types and ore-forming element associations show clear spatial zones around the porphyry. The magmatic activity is synchronous to Cu-Mo-Au mineralization. The three types are genetically controlled by the Machangqing porphyry magma system which supplied material, fluid and dynamic force for the mineralization. Based on a detailed analysis of the mineralization evidence and the structure of the ore system, the authors have concluded that the thermal dynamic force from Machangqing intrusion caused the migration of the ore-forming fluid from the magma outwards. With the variation of physical and chemical conditions of fissures in the intrusive body as well as contact structures and fracture zones in the wall rock, there occurred different mineralization types and metallogenic element associations under different conditions. In general, with the evolution of hydrothermal mineralization, the mineralization was developed from porphyry through the contact zone to the wall rock, and from high-T to low-T correspondingly. The establishment of the Cu-Mo-Au polymetallic metallogenic system for the Machangqing ore concentration area will help the study of mineralization theory and the exploration practice in the west Yunnan metallogenic belt.