广西佛子冲铅锌矿绿色岩REE地球化学特征及成矿指示意义

佛子冲铅锌矿田广泛发育与成矿密切相关的绿色岩,然而其成因归属却极具争议.野外考察发现该类特殊岩石存在4种产状类型:层状、块状、脉状和角砾状.稀土元素分析结果表明:绿色岩具有高的ΣREE、LREE/HREE、LaN/YbN,负Eu异常,无Ce异常,这些特征均与花岗斑岩和钾长石化花岗岩比较接近;随着矿化作用的增强,绿色岩的稀土元素含量逐步降低.结合岩矿鉴定、地质特征对比研究认为,佛子冲绿色岩与典型的接触交代矽卡岩特征相似,而与热水沉积喷流岩差别较大,表明佛子冲的“绿色岩”属岩浆期后热液接触交代的产物,绿色岩的发育与成矿作用关系密切,对矿床成因与成矿预测研究具有重要意义.

REE Geochemical Characteristics of Green Rock in Fozichong Lead- Zinc Deposit and Genesis Implications

The widely distributed green rock in Fozichong orefield is closely related to mineralization, but ex, tremely controversial on the genesis. Based on the field work, the green rock can be classified into four types： the beded type, the massive type, the veinlike type and the breccia type. The REE geochemisty reveals that it is characteristic of high ∑REE, LREE/HREE and LaN/YbN, negative Eu anamoly, and no Ce anamoly, similar to granite porphyry. The REE content of green rock is progressively reduced with the intensive mineralization. Comparative study on the geological and geochemical characteristics of the typical skarn rock and exhala~ tive rock, it is suggested that the green rock of the Fozichong lead-zinc deposit should be the post-magmatic hy- drothermal metasomatic product and closely related to mineralization. It has important significance on the genesis of the deposite and the research of metalloge nesis of the Fozichong ore deposit.