哀牢山金矿带成矿流体稀土元素地球化学

REE Geochemistry of Ore-forming Fluids of the Ailaoshan Gold Metal logenic Belt

本项研究测定了矿石、蚀变围岩和相应未蚀变岩石的稀土元素组成。通过对这些地质体稀土元素地球化学特征的对比研究发现,在成矿流体的演化过程中,镇流和墨江两个金矿床成矿流体的稀土模式具有明显的变化,而大坪金矿成矿流体的稀土模式则保持相对不变。因此,大坪金矿的稀土模式(轻稀土高度富集、弱负Eu异常和较强负Ce异常)可以代表初始成矿流体的稀土模式。研究表明,具有这种稀土模式的流体,可能是由地幔会气作用产生的地幔流体。

REE compositions of ores, altered rocks and related unaltered rocks have been determined. Comparative studies of REE geochemical characteristics of these geologic bodies indicate that REE patterns of ore-forming fluids in the Zhenyuan and Mojiang gold deposits show marked changes, while that of the Daping gold deposit remains relatively unchanged. Therefore, the REE pattern (strong LREE enrichment, weak negative Eu anomaly and strong Ce anomaly) of ore-forming fluids of the Daping gold deposit can represent the REE pattern of primary ore-forming fluids. Studies indicate that the ore-forming fluids with such a REE pattern might be CO2-riched mantle fluids produced by mantle degassing.