Accurate Determination of Rare Earth Elements in Scheelite Using High Resolution-Inductively Coupled Plasma-Mass Spectrometry——An Instance of Nanyangtian Scheelite Mining, Malipo, Yunnan
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ABSTRACT
The rare earth elements (REEs) in two different types of ores and wall rocks in Nanyangtian scheelite mining, Malipo, Yunnan, were accurately determined by High Resolution-Inductively Coupled Plasma-Mass Spectrometry (HR-ICP-MS). The method of REEs determination is reliable and of high sensitivity, with a low detection limit and satisfactory precision and accuracy. The geochemical characteristics of REEs show the existence of two different types of scheelite ore. The first one is skarn scheelite which is derived from sedimentary scheelite deposits by late metamorphism. The second is quartz-vein scheelite with high REEs content by late stage hydrothermal fluid. The former has rich LREEs and depleted HREEs, a medium degree of negative Eu and Ce anomaly, which are closely related to the sedimentary environment, supposedly the diagenism product around submarine volcano eruption. The latter has low amounts of ∑REEs and an outstanding positive Eu anomaly, reflecting the strong fractionation of REEs, probably formed by later stage hydrothermal activities. The superimposition-reformation for early ore bodies by late stage hydrothermal fluid improved the mineralization enrichment.
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