Rare Earth Elements Geochemical Characteristics and Its Implication for Ore Genesis in Saxi Scheelite Deposit, Southeast Yunnan Province
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摘要: 洒西白钨矿床位于滇东南老君山矿集区内,呈层状、似层状产出。矿区围岩为一套中深变质岩,其稀土元素组成特征为:矿区围岩LREE/HREE比值为4.37~6.87,15Eu为0.67~1.49,6Ce值为0.62~0.98;外围混合片麻岩LREE/HREE比值为4.51~5.58,6Eu平均为0.14。矿石Eu正异常与Ce负异常同时存在说明矿石沉淀时相对高温的热水流体和较低温的海水在海底发生了对流混合,部分样品中Eu负异常的形成可能与后期岩浆热液叠加改造作用有关。结合矿床地质特征,洒西白钨矿床成因为喷流沉积.后期岩浆热液改造型。Abstract: Saxi scheelite deposit is occurred in bed, or stratiform in Laojunshan ore cluster region, southeastern Yunnan province. The wall-rocks are a suit of mesometamorphic rocks. The different rocks have got different rare earth elements composition: wall-rocks have the LREE/HREE ratio of 4.37 - 6.87, δEu value of 0.67 - 1.49, δCe value of 0.62 - 0.98; periphery migmatitic gneiss with LREE/HREE ratio of 4.51 5.58, average δEu value of 0.14. The positive Eu anomalies and negative Ce anomalies of ore indicated that the ore precipitation by the mixing of relative high-temperature hydrothermal and lower-temperature seawater, while negative Eu anomalies of some samples maybe caused by later magmatic hydrothermal superimposition. The geochemical and geological evidence indicated that Saxi seheelite deposit is formed by exhalative-late magmatic hydrothermal process.
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