易门铜矿区深部岩浆热液叠加成矿作用研究——以狮子山铜矿为例

Magmatic hydrothermal superimposed mineralization is one of the topics at the forefront of today's deposits Studies, whether there is hydrothermal superimposion mineralization or not in the deep of Yimen copper is a major problem which need to study. Through research we can find that the deep quartz albite veins in close quarters with the copper mineralized quartz veins, high-temperature elements (Mo, Bi) enrichment in copper ore,ore fabric and mineral composition showing complex features,especially found high temperature - high salinity fluid inclusion in the deep of Shizishan copper deposit, the above information reflect that there is superposition of magmatic hydrothermal mineralization in the deep, which speculated that the deep existence copper-polymetallic deposit relationship with porphyry.Therefore, this study intended to be the Shizishan copper deposits as the main object，around the "Time - space - material" three elements of the mineralization,to the petrography of fluid inclusions as a breakthrough point, on the basis of the fine analysis of the typical deposit,by studing the fluid inclusions of copper-bearing quartz veins, quartz 39Ar-40Ar, and chalcopyrite Re-Os isotopic age analysis to clarify that the mineral， source of ore-forming fluid and mineralization P-T-X conditions in the magmatic hydrothermal superimposition，determine the age of superimposed mineralization, to reveal its mechanism of mineralization; by compared with the typical deposit surrounding mining area, provide theoretical support for finding the new types of deposit and new minerals in the deep of Dongchuan - Yimen rift valley copper belt.

岩浆热液叠加成矿作用是当今矿床学研究的前沿课题之一。易门铜矿区深部是否存在岩浆热液叠加成矿作用需要重点研究，研究发现矿区深部石英钠长石岩脉与铜矿化石英脉紧密共生，铜矿石中富集高温元素（Mo、Bi），矿石组构和矿物组成复杂多样，特别是易门狮子山铜矿深部含铜石英脉的石英矿物中发现高温-高盐度流体包裹体，指示了深部存在岩浆热液叠加成矿作用，并推测深部可能存在与斑岩有关的铜多金属矿床。因此，拟以狮子山典型铜矿床为主要对象，围绕成矿作用的"时-空-物"三要素，以流体包裹体岩相学研究为突破点，在典型矿床精细解剖的基础上，通过含铜石英脉流体包裹体研究、石英39Ar-40Ar定年和黄铜矿Re-Os同位素年龄分析，阐明岩浆热液叠加作用中成矿物质、成矿流体来源及成矿T- P -X条件，厘定叠加成矿时代，揭示其成矿机制，并与周边典型矿床进行对比研究，为东川-易门裂谷铜矿带深部发现矿床新类型和新矿种提供理论支撑。

易门狮子山铜矿位于易门铜矿东矿带，是昆阳元古宙裂谷易门地区“东川式”铜矿的典型代表，通过开展构造-蚀变分带研究、含铜石英脉流体包裹体研究、黄铜矿Re-Os同位素定年和矿床C-H-O-S同位素地球化学特征研究，阐明了狮子山铜矿岩浆热液叠加成矿作用中的成矿流体来源和成矿T-P-X条件，成矿物质来源，初步测定了构造改造（叠加）成矿作用时代，为东川-易门裂谷铜矿带矿床研究提供了有利依据。.（1）通过构造-蚀变分带填图研究认为：狮子山铜矿①号矿体和⑧号矿体受狮子山背斜NW翼次级背斜中的刺穿构造控制明显，由刺穿体→围岩存在以下分带：①绿泥石化、硅化带；②硅化带；③碳酸盐化带。.（2）流体包裹体研究认为狮子山铜矿成矿流体为H2O-NaCl体系，包裹体分三大类：含子矿物包裹体（S型）、液体包裹体(W型)和气体包裹体（V型）。矿区高温阶段不同相比的S型、V型、W型包裹体共生，且均一温度相同，说明成矿流体经过沸腾作用，不是简单的浅表热卤水，而是伴有深源流体叠加的混合流体。推测深源流体来自深部岩浆热液（与辉长岩有关）可能性较大，构造作用和岩浆侵入作用提供的热能活化了地层中成矿物质，伴随岩浆热液的叠加作用，将成矿物质沿着刺穿构造运移到有利的成矿部位成矿。.（3）同位素研究表明：狮子山铜矿碳可能来源于海相碳酸盐和深源两种；硫同位素有海水硫酸盐和深源硫两种。.（4）通过对黄铜矿进行Re-Os同位素测年，认为构造改造成矿作用年龄为1524±68Ma，结合矿区流体包裹体的特征及矿床特征，推测可能与易门地区辉长岩侵入年龄一致。.综上所述，认为狮子山铜矿是沉积-构造改造-深源岩浆热液叠加作用形成的矿床。