陆相砂岩型铜矿床矿物组合分带的logfo_2-logfs_2相图——以云南大姚六苴铜矿床为例  

logfo_2-logfs_2 FACIES MAP OF MINERAL ASSEMBLAGE MODEL OF SANDSTONE-HOSTED COPPER DEPOSITS——TAKING THE DAYAO LIUJU COPPER DEPOSIT FOR EXAMPLE

作　　者：张艳[1,2] 韩润生[1,2] 吴鹏[1,2] 魏平堂 

机构地区：[1]昆明理工大学 [2]有色金属矿产地质调查中心西南地质调查所,云南昆明650093 [3]中国冶金地质总局昆明地质勘查院,云南昆明650024

出　　处：《矿物岩石》2013年第2期35-42,共8页Mineralogy and Petrology

基　　金：教育部博导基金(20115314110010);国土资源部典型矿科学基地公益性项目;国家危机矿山专项(20089943);国家自然科学青年科学基金(41102049);中国科学院矿床地球化学国家重点实验室开放研究基金(201109);云南省高校;昆明理工大学成矿动力学与隐伏矿预测创新团队项目(2010)

摘　　要：根据矿物生成吉布斯自由能ΔG在373K、423K、473K、523K温度下用Excel表格编写公式的方法计算了云南大姚六苴铜矿床中铁、铜单质及其氧硫化物等共22种矿物及其矿物组合系统的氧硫逸度(logfo2,logfs2),以logfo2-logfs2和373K,423K,473K,523K为约束条件构建了上述矿物及矿物组合的系统平衡相图4幅。以423K相图为例,解析后得出22种矿物及其组合稳定存在的logfo2,logfs2范围和该相图的氧化还原区块分布趋势。将相图氧化还原态势区块分布与六苴铜矿床中以氧化还原态势为基础的矿物组合与分带进行了对比分析,结果表明矿物氧-硫逸度相图中矿物的排列组合和矿物组合本身反映的氧化还原态势一致,而且也和该矿床地质产状上的矿物共生组合及矿物分带相符合。据此判定氧-硫逸度对六苴铜矿床形成的氧化还原态势、主要金属矿物组合沉淀及矿物组合分带起控制作用。温度下降,矿物沉淀的logfo2-logfs2值随之减小,氧化还原作用趋弱,矿物稳定范围(相图中占据的区块)向Fe,Cu单质移动,但辉铜矿占据的氧化还原过渡区块的面积始终很大,表明辉铜矿沉淀的逸度范围很宽。Based on the Gibbs free energyΔG of mineral generation at 373K,423K,473K,523 K temperature,the oxygen and sulfur fugacity（logfo2,logfs2）of the simple substance iron,copper and oxysulfides,total of 22kinds of minerals and mineral combination have been calculated by the writing formulas in Excel sheet to study the geochemical character of Dayao Liuju copper deposit.4balance system phase figures containing above minerals and mineral assemblages was constructed by constraints of the logfo2,logfs2at 373K,423K,473K,523K.Stable logfo2,logfs2 range of the 22kinds of minerals,their combinations and the trend of the redox block distribution can be obtained by analyzing the phase diagram.Correlation of the redox block trend distribution in the phase diagram and the mineral assemblage zonation showed that the mineral permutation and combination in the phase diagram were consistent with the the trend of redox reflecting by minerals and mineral assemblages and the mineral assemblages and mineral zonation on the geological occurrence.Therefore,it is believed that oxygen-sulfur fugacity controlled the redox trend,and affected metal mineral assemblages precipitation and mineral assemblage zonation in Liuju copper deposit.When temperature drops,logfo2,logfs2value decreases,and the redox effect is weaker.The mineral stability range（the block occupied in the phase diagram）is moving to Fe,Cu elementary substances with the temperature declining.However,the fact that chalcocite occupies large area of oxidation-reduction indicated that chalcocite has a very wide range of precipitated fugacity.

关 键 词：大姚铜矿床 砂岩铜矿 矿物组合 氧逸度 硫逸度 矿物logfo2-logfs2相图 

分 类 号：P57[天文地球—矿物学]