扬子地块西南缘拉拉IOCG矿床矿化蚀变元素地球化学研究  

Geochemistry of Mineralization and Alteration Elements in the Lala IOCG Deposit,Southwest Margin of Yangtze Block

作　　者：吴燕飞[1,2] 李泽琴[1] 黄从俊[1] WU Yanfei LI Zeqin HUANG Congjun(College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国科学院地球化学研究所,贵州贵阳550081

出　　处：《大地构造与成矿学》2016年第5期960-974,共15页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41072065);教育部博士点基金(20105122110001);西南地区主要成矿带铜铁金多金属找矿模型与勘查方法技术研究(12120113095500);矿床地球化学国家重点实验室(200808);四川省教育厅重点项目(07ZA005)联合资助

摘　　要：拉拉IOCG矿床是我国西南地区著名的大型铁铜矿床,矿床中与铜(钼)矿化密切相关的钠长石化、碳酸盐化、钾长石化、黑云母化、萤石化等蚀变作用广泛发育。本文在对该矿床中黑云母片岩系列和钠长石变粒岩系列大量赋矿岩石样品进行岩相学研究的基础上,选取典型蚀变与矿化样品进行主、微量元素分析测试,通过质量比簇判别法和等浓度公式元素定量迁移计算研究矿床中蚀变元素特征及其与矿化的关系。质量比簇判别法和等浓度图解法确定了两个系列岩石共有的主量元素不活动组分为SiO_2,微量元素不活动组分为Yb。主量元素定量迁移计算表明黑云母片岩系列铜矿化与钠长石化和碳酸盐化成正相关关系,钠长石变粒岩系列铜矿化与钾长石化和碳酸盐化成正相关关系,且变粒岩系列碳酸盐化程度较片岩系列更强。稀土元素和金属元素定量迁移计算发现拉拉IOCG矿床中U、Co、Mo、Ni等成矿金属元素在蚀变过程中随Cu矿化大量带入,说明热液蚀变是拉拉Fe-Cu-Au-U-Mo-REE多金属矿床形成的主要原因。蚀变与矿化关系分析表明二者基本是同步发生,蚀变的过程也是矿化的过程,即蚀变的标志也是找矿的标志。拉拉IOCG矿床中蚀变元素地球化学特征及其与矿化关系的研究,对于矿床成矿理论的丰富及矿区进一步找矿勘探工作都具有重要意义。The Lala Iron-Oxide-Copper-Gold（IOCG） deposit is the largest copper deposit in southwest margin of Yangtze Block. Alteration is well developed in this deposit, which has a close relationship with the mineralization of chalcopyrite and molybdenite. The wall-rock alterations are mainly including albitization, carbonatization, K-feldspar alteration, biotitization and fluoritization, etc. 23 typical host rock samples were picked out to disscuss their alteration elements geochemistry, and relationship between alteration and mineralization based on the petrography and elements analysis. These samples are all come from biotite schist series and albite granulite series. The major elements analysis by means of ME-XRF26 and ME-XRF15 bg, and the trace elements analysis by using the method of ICP-MS. The study of cluster discriminant method of mass ratio suggests that the most inactive major element component of the two series rocks is SiO_2. Besides, the most inactive trace element component of biotite-schist series and the albite-granulite series is Yb. On the other hand, quantitative elements migration was calculated by using the concentration formula according to the principle of mass conservation. Major elements quantitative migration calcuation suggests that the copper mineralization of biotite-schist series has a positive relationship with albitization and carbonatization, while albite-granulite series have a positive relationship with the K-feldspar alteration and carbonatization. Carbonatization is much stronger in biotite-schist series than that in the albite-granulite series. Na_2O and K_2O have an opposite relationship in two series of rocks, for example, K_2O is usually brought out while Na_2O is brought in. Quantitative calculation of the REE and metal elements migration suggests that a mass of REE, U, Cr, W, Co, Mo, Ni are brought in accompany with the alteration and copper mineralization of the rocks. The migration content of these elements are usually far more than 1, the maximum migration content of Mo

关 键 词：拉拉IOCG矿床 围岩蚀变 不活动组分 质量迁移计算 

分 类 号：P611[天文地球—矿床学]