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北衙金多金属矿床是三江特提斯成矿域中喜马拉雅期斑岩-矽卡岩型矿床的典型代表。对该矿床钾质斑岩、蚀变斑岩、斑岩型矿石、矽卡岩、矽卡岩矿石、灰岩内热液脉型矿石、蚀变灰岩到灰岩的稀土元素进行了系统的分析测试。结果表明:斑岩型铜金矿石的稀土配分模式为轻稀土富集的右倾型,具Eu弱的负异常,总体继承钾质斑岩体稀土元素特征,成矿流体主要为岩浆热液。矽卡岩稀土配分模式变化较大,可分为三种类型:直线型稀土配分模式、折线型稀土配分模式及平坦型稀土配分模式,其中折线形稀土配分模式呈现Eu正异常。本区矽卡岩属接触交代成因,稀土配分模式的特征与变化特征说明矽卡岩型铁金矿石主要形成于矽卡岩化后期,成矿环境总体上为水-岩比值较大的高温氧化环境。灰岩内热液脉型矿石稀土配分模式为轻稀土富集的右倾型,具Eu正异常,表明热液型矿石形成于较为开放的氧化环境,大气降水与岩浆热液的混合是矿石沉淀的主要机制。北衙金多金属矿床的矿石稀土元素配分曲线变化较大、类型多样,充分显示了成矿流体的多来源和多阶段成矿特征。为北衙矿区成矿作用过程与机制研究提供了稀土元素方面的证据。
The Beiya gold polymetallic deposit is a typical representative of the Himalayan porphyry-skarn deposits in the Sanjiang Tethys metallogenic area. The authors systematically analyzed the rare earth elements in the porphyry potash, altered porphyry, porphyry ore, skarn, skarn ore, hydrothermal veins of limestone, altered limestone and limestone test. The results show that the REE pattern of porphyry copper-gold ore is right-leaning with light rare earth enrichment and weak anomaly with Eu. Generally, the REE inherits the characteristics of REE, and the ore-forming fluids are mainly magmatic hydrothermal fluids. There are three types of skarn REE patterns, which can be divided into three types: linear REE, linear REE and flat REE, in which the zonal REE shows Eu positive anomaly. The origin and origin of the skarn in this area is that the pattern of the REE pattern shows that skarn-type iron-gold ore is mainly formed in the late stage of skarnization. The ore-forming environment is generally high-temperature oxidation with large water-rock ratio surroundings. The REE pattern of the Limaite hydrothermal vein ore is a right-leaning type with LREE enrichment and positive Eu anomalies, indicating that the hydrothermal ore is formed in a relatively open and oxidizing environment. The mixing of atmospheric precipitation and magmatic hydrothermal fluids is the main deposit of ore mechanism. The REE distribution patterns of Beiya gold polymetallic deposits vary widely with different types and fully show the multi-source and multistage metallogenic characteristics of ore-forming fluids. The study provides the evidence of rare earth elements for the study on the process and mechanism of mineralization in Beiya mining area.