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-XRF15bg, 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 SiO2. 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. Na2O and K2O have an opposite relationship in two series of rocks, for example, K2O is usually brought out while Na2O 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 is up to 43655.4%, which suggests that the hydrothermal alteration is the main reason for the Cu-Au-U-Mo-REE polymetallic mineralization. Alteration and mineralization are generally synchronous in this deposit, that is to say the process of alteration is also the process of mineralization, and alteration is one of the indicators for this deposit. Understanding the geochemistry of alteration elements and its relationship with mineralization in the Lala IOCG deposit have important significances in both enriching metallogenic theory and directing exploration.%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SiO2,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。
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