云南大红山铜铁矿床稀土元素地球化学特征初探

Preliminary Study of REE Geochemistry of Copper and Iron Deposits in Yunnan Dahongshan

文中主要选取大红山铜铁矿床典型穿脉进行构造-岩石地球化学编录,系统取样并对样品稀土元素进行化验分析。研究表明：（1）该矿区内各类岩（矿石）从矿化构造岩→矿石→未矿化构造岩的稀土总量呈现出逐渐降低的趋势,反映出成矿流体与不同构造岩的水岩反应程度上的差异。（2）从（La∕Yb）N看,该矿区内同类断裂构造岩的轻稀土分异程度较大,但不同断裂构造岩间的分异性却较为均一,从该区围岩、矿石、构造断裂岩的LREE∕HREE与（La∕Yb）N比值特征中可以看出,轻稀土元素与重稀土元素间的分异程度具有一定的相似性,反映出成矿流体对地层岩石存在着一定的继承性,却又具有一定的阶段演化性特征。（3）从地层岩石→未矿化断裂构造岩→矿化断裂构造岩→块状、条带状矿石,LREE∕HREE（5.66-13.27）有逐渐增大的趋势,反映出在断裂构造作用过程中,稀土元素发生了迁移;该矿区内各类岩（矿）石的δEu均大于1,δCe弱负异常,显示出大红山铜铁矿床的成矿作用主要是在相对氧化的环境下进行。

This article focuses on the structures and geochemistry of veins that are typically cross-curring the Dahongshan copper andiron ore deposits. Systematic sampling was conducted and the REE geochemistry of samples was analyzed. The results show that（1） the mine in the region of various types of rock（ore） shows a decreasing trend in REE amount from mineralized tectonite, to ore, tonon-mineralized tectonite, which reflects differences in the degree of water-rock interactions between ore-forming fluids and rocks;（2） the（La/Yb）Nshows that LREE of similar tectonite in the mine displays large degree of fractionation, but different tectonites showrelatively uniform differentiation. LREE / HREE and（La/Yb）Nratio characteristics of the surrounding rocks, ore and tectonites indicatethat there is similarity in the degree of fractionation between LREE and HREE, suggesting that the REE of the ore-forming fluids isinherited in certain rocks;（3） LREE / HREE（5.66-13.27） shows a gradual increase from formation of rock, tonon- mineralizedtectonite, to mineralized tectonite, to blocky and stripped ores, reflecting REE migration in the process of fracturing; The δEu of various types of rock（ore） is greater than 1 and δCe shows a weak negative anomaly, suggesting that Dahongshan copper and iron oremineralization took place in a relatively oxidizing environment.