云南播卡晚元古代岩浆作用与成矿效应：一种可能的IOCG模式

The copper-polymetallic mineralization concentration area of Dongchuan, Central Yunnan located at the middle of the passive continental rift system along the west margin of Yangtz craton, west of Dongchuan-Huili aulacogen. A series of previous research on the genesis and mineralization of the copper-polymetallic deposits of Dongchuan have been studied, and all of the research nearly focused on ore-formation and ore-controlling structure, as well as prospecting indicators, but the alkaline magmatism and its relationship between mineralization, which has obvious correspondence in time and space with the orebody were seldom mentioned. Hence, in this project the alkali-rich porphyry of Jinningian located at the east margin of the middle of Kangdian Continental shaft, which is related with the mineralization such as copper, gold, iron of Boka orefield in Dongchuan will be studied. Based on the petrography, mineralogy, fluid inclusions and isotope geochemistry and modern isotopic dating data, identifying the temperature, pressure, analytical data of liquids and gases of mineralization, and the characteristics and sources of fluids will be explained. Based on the above studies, in combination with the regional geological background, geological features, we will make further discussions on the genesis and mechanism of mineralization, and a possible IOCG deposits type metallogenic model will be constructed, and geological basis for identifying the specific process of copper polymetallic mineralization in Dongchuan will be provided. This study will make up for the tectonic-magmatic events in Dongchuan area, and also contribute to the constraints of the polymetallic mineralization mechanism, and thus which has important scientific significance and economic value.

滇中东川铜多金属矿集区，在大地构造上属于扬子地台西缘被动大陆裂谷系中部，东川-会理坳拉槽西端。前人已对东川铜多金属矿的矿床成因及成矿作用进行过一定程度的研究，但重点均集中在赋矿层位、控矿构造以及找矿标志方面，而与矿体在时空上存在明显对应关系的碱性岩浆活动及成矿作用的研究有限。鉴于此，本项目拟以康滇地轴中段东缘东川播卡矿田与铜、金、铁矿化作用密切的晋宁期富碱斑岩作为研究对象，通过系统的岩石学、矿物学、流体包裹体和同位素地球化学及年代学研究，查明其成矿温度、成矿压力以及成矿流体性质、来源及化学组成，并结合区域地质背景、矿床地质特征，阐明其矿床成因、成矿作用机制，构建一种可能的IOCG矿床类型铜-金-铁矿成矿模式，为识别东川铜多金属成矿作用具体过程提供地质依据。这一研究既可以弥补该区构造-岩浆热事件的研究空白，也有助于对多金属矿床的成矿机理进行约束，因而具有重要的科学意义和经济价值。

云南东川铜多金属矿集区位于云南省东川市境内，是我国重要的铜矿基地之一。随着勘查工作的深入，研究者逐渐认识到区内铜金多金属矿床与广泛发育的钠长（斑）岩体有密切的成因联系。为进一步理清、查明矿床成因及控矿因素，充实矿床科技理论的同时，充分发挥其对本区铜、金、铁找矿勘查工作的科技引领作用，项目组通过国家自然科学青年基金开展系统全面地针对性研究工作，并取得主要认识如下：.1） 研究表明，播卡钠长岩主要造岩矿物有钠长石、辉石、黑云母，主量元素特征显示其为富碱、高钠、偏铝质的碱性-过碱性岩石。岩石的稀土总量ΣREE低，相对富集轻稀土，明显富集大离子亲石元素K、Rb、Nd及轻稀土元素 La、Ce、Sm，相对亏损高场强元素Nb、Ta、U、Th等。岩石的Isr值、εNd（t）值显示其可能为中元古代晚期会理-东川一带大陆裂谷岩浆作用的产物，来源于深部地幔，其源区可能有部分陆壳物质的参与。.2） 播卡金矿床流体包裹体均一温度在105～368℃，盐度在4.18～44.32 wt. %(NaCleq)，流体包裹体气相成分以H2O为主，其次为少量CO2，液相成分以Na+、Cl-为主，其次为Ca2+、SO42-，成矿流体主要属于NaCl-H2O体系。.3） 矿床硫、铅同位素测试结果表明，人占石铜矿金属硫化物的δ34S值从1.6‰至10.7‰，表明硫以岩浆作用（火山喷发）为主要来源；新山金矿金属硫化物的δ34S值从-7.0‰至9.0‰，表明硫是岩浆源区硫和地层源区硫在成矿热液系统中高度混合均匀化的产物。铅同位素组成分析则表明人占石铜矿、天生塘铜矿、竹箐凹子铜矿和白石岩铜矿其铅主要来源于壳幔混合。综合分析，认为播卡铜（金）矿床成矿物质主要来自于深部岩浆，这种岩浆可能起源于俯冲洋壳板片的部分熔融，同时受到地壳物质的混染。.4） 播卡地区的金（铜）矿床是中、新元古代辉绿（辉长）-钠长岩系岩浆-热液成矿系统演化的产物，矿床成因类型可归属至岩浆热液型金（铜）矿。