Abstract—

The major objective of the study investigation was to find the physicochemical conditions for U, Nb, and Ta mobilization into the solution from acidic melts similar in composition to rhyolitic inclusions in quartz at the unique Streltsovka Mo–U field (Eastern Transbaikalia). The experiments were performed with model homogeneous leucogranite glass (wt %): 72.18 SiO₂, 12.19 Al₂O₃, 1.02 FeO, 0.2 MgO, 0.33 CaO, 4.78 Na₂O, 3.82 K₂O, 1.44 Li₂O, and 2.4 F (LiF, NaF, KF, CaF₂, and MgF₂); synthetic uranium dioxide; and natural columbite in solutions containing from 1 to 8 mol kg^–1 chlorides (Na, K, and Li) at 750°C, 1000 bar, with an O₂ (H₂) fugacity set by the Ni–NiO buffer. The selected T–P parameters and solutions corresponded to the homogeneous and fluid immiscibility regions in the NaCl–KCl–H₂O solutions. The Nb and Ta contents in the Cl–F solutions in equilibrium with F-bearing melts are very low. The U content is much higher and reaches about 1 × 10^–4 wt % in the low-density fluid phase and n × 10^–3 wt % in the dense aqueous saline phase (brine). The U content in the glass was tenths of a percent. Despite the very high chlorine content in the studied solutions, its content did not exceed 0.5 wt % in the glass. In the course of the experiments, columbite dissolved incongruently in the glass melt to form F- and U-bearing pyrochlores. According to the investigation results, the predominantly chloride fluid with the studied T–P parameters should not be considered an active medium for mobilization of U from Li–F granite melts in the formation of unique hydrothermal U (Mo–U) deposits.

中文翻译：

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在750°C和1000 Bar的花岗岩熔体-氯化物流体系统中铀，铌和钽行为的研究

摘要—

研究调查的主要目的是在独特的Streltsovka Mo-U场（东跨贝卡利亚）中，从与成分类似的石英中流变夹杂物的酸性熔体中找到将U，Nb和Ta迁移到溶液中的物理化学条件。实验是用模型均匀淡色花岗岩玻璃（重量％）进行：72.18的SiO ₂，12.19的Al ₂ ö ₃，1.02的FeO，0.2的MgO，0.33的CaO，4.78的Na ₂ O，3.82ķ ₂ O，1.44李₂ O，和2.4 F（LiF，NaF，KF，CaF ₂和MgF ₂）；合成二氧化铀 和天然co石溶液中浓度为1至8 mol kg ^–1氯化物（Na，K和Li）在750°C，1000 bar下通过Ni–NiO缓冲液设定的O ₂（H ₂）逸度。选定的T – P参数和溶液对应于NaCl–KCl–H ₂ O解决方案中的均相和流体不混溶区域。与含氟熔体平衡的Cl-F溶液中的Nb和Ta含量非常低。U含量高得多，在低密度液相中约为1×10 ^–4 wt％，n  ×10 ^–3在浓盐水相（盐水）中的重量％。玻璃中的U含量为百分之十分之一。尽管所研究溶液中的氯含量非常高，但其含量在玻璃中并未超过0.5 wt％。在实验过程中，co石在玻璃熔体中溶解程度不一，形成了含F和U的烧绿石。根据调查结果，主要是具有研究过的T - P参数的氯化物流体，不应被视为从独特的热液U（Mo-U）矿床中形成的Li-F花岗岩熔体中移动U的活性介质。