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对粤北长江铀矿田赋矿花岗岩、蚀变花岗岩、铀矿石、沥青铀矿、黄铁矿、方解石和萤石开展了系统的REE,U与Th的地球化学研究,结果显示各类样品表现出类似的LREE相对富集、HREE相对亏损和Eu负异常的地球化学特征,表明样品REE特征具有一定的继承性,继承了赋矿花岗岩的REE特征。成矿早期钠交代作用对花岗岩中REE迁移较小,但对U有预富集作用,成矿期热液蚀变对花岗岩中REE迁移较明显,尤其是HREE,而Th表现出相对稳定的特征。从成矿早期到晚期方解石ΣREE逐渐降低(ΣREE平均值由48.86×10~(-6)→43.52×10~(-6)→28.40×10~(-6)),Eu负异常趋于减弱(δEu均值由0.23→0.31→0.39),表明成矿流体向相对氧化环境演化。成矿热液中REE,U与Th活化、迁移具同步性和同时性。热液沸腾和去气作用是造成沥青铀矿、方解石和萤石相对富集HREE的原因。由成矿早期到成矿晚期,成矿热液向相对氧化的酸性流体演化。
A systematic REE, U, and Th geochemical study was carried out on porphyry granite, altered granite, uranium ore, uraninite, pyrite, calcite and fluorite in the uranium orefields of northern Guangdong. The results showed that all samples showed Similar LREE enrichment, relative depletion of HREEs and geochemical characteristics of Eu anomalies indicate that the REE characteristics of the samples have a certain degree of succession and inherit the REE characteristics of the ore-beneficiated granites. In the early stage of metallogenesis, the REE migration in granite is less, but it is pre-enriched in U. The hydrothermal alteration during mineralization has obvious REE migration in granite, especially HREE, while Th shows relatively stable features . From the early to late calcification, the ΣREE of calcite gradually decreases (the average value of ΣREE ranges from 48.86 × 10 -6 to 43.52 × 10 -6 to 28.40 × 10 -6), and the negative Eu anomaly tends to weaken δEu mean value from 0.23 → 0.31 → 0.39), indicating that the evolution of ore-forming fluid to the relative oxidation environment. REE, U and Th activation in mineralization hydrothermal fluids with synchronism and simultaneity. Hydrothermal boiling and degassing is the reason that HREE is relatively enriched in bitumen uranium, calcite and fluorite. From the early stage of metallogenesis to the late stage of metallogenesis, the ore-forming hydrothermal fluids evolve to the relatively oxidized acidic fluid.