Abstract

The distributions of niobium mineral deposits and their resources on the geological time scale are analyzed. The sampling list includes 45 mineral deposits with their individual resources estimated not less than 10⁵ tons of Nb₂О₅. The classification of deposits used includes three types, namely, alkaligranitic, foidic, and carbonatitic. The geohistorical variability in niobium metallogeny is presented through comparison of supercontinent cycles. To date, no deposits belonging to the Kenoran cycle, which are of interest for the targeted extraction of niobium, have been identified. The Columbian cycle is the oldest among the significant cycles in niobium metallogeny, but its resources are relatively small. The most significant resources of niobium are related to alkaline igneous complexes of the Rodinian, Pangean, and Amasian cycles. The resources of carbonatitic deposits are sharply predominant among all resources generated in the cycles of geological history considered. A consistent increase in the share of resources of such deposits is established through the chronological sequence of supercontinent cycles. The maximum amount of resources of the foidic type is concentrated in the deposits of the Rodinian cycle, while a much smaller amount is in those of the Columbian and Pangean cycles, and no foidic deposits have been identified in the Amasian cycle. The alkaligranitic type demonstrates the smallest fluctuations in niobium resources among the cycles compared; however, its relative contribution to the total resources of all cycles is very small, except for the low-productive Columbian cycle. Despite the close relationships between niobium and tantalum in the mineral-forming processes, these elements do not always show mutually comparable ore concentrations in terms of economic value in the same deposits. Such a coincidence chiefly takes place in mineral deposits of the foidic and alkaligranitic types, which are not yet of great importance in real extraction of both niobium and tantalum. In terms of economic value, carbonatites are almost always specialized exclusively in niobium, while rare-metal pegmatites and granites are specialized in tantalum. These types of mineral deposits are formed in completely different geodynamic environments from magmas of contrasting composition that originated in different lithospheric layers. Therefore, the revealed differences in the historical metallogeny of these two metals have a logical explanation.

中文翻译：

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铌成矿中的超大陆循环的比较

摘要

分析了地质时间尺度上铌矿床的分布及其资源。取样列表包括45种矿藏与他们的单个资源估计不小于10 ⁵吨的Nb ₂ О ₅。所使用的沉积物的分类包括三种类型，即碱粒岩，片状和碳酸盐岩。通过比较超大陆循环来显示铌成矿的地球历史变异性。迄今为止，还没有发现属于Kenoran循环的矿床，这些矿床是有针对性地提取铌所感兴趣的。哥伦比亚成矿周期是铌成矿周期中最古老的周期，但其资源相对较少。铌的最重要资源与Rodinian，Pangean和Amasian周期的碱性火成岩复合物有关。在所考虑的地质历史周期中，碳酸盐岩矿床的资源在所有资源中占绝对优势。通过超大陆循环的时间顺序可以确定此类矿床资源份额的持续增长。Foidic类型的最大资源集中在Rodinian周期的矿床中，而较少的数量在Columbian和Pangean周期的矿床中，并且在Amasian周期中没有发现Foidic矿床。在所比较的循环中，碱gra石型铌资源的波动最小。然而，除了低产的哥伦比亚周期之外，它对所有周期总资源的相对贡献很小。尽管铌和钽在成矿过程中关系密切，但就同一矿床而言，就经济价值而言，这些元素并不总是显示出相互可比的矿石浓度。这种巧合主要发生在浮游型和碱成岩类型的矿床中，这些矿床在铌和钽的实际开采中尚不重要。就经济价值而言，碳酸盐岩几乎总是专门用于铌，而稀有金属伟晶岩和花岗岩则专门用于钽。这些类型的矿床是在完全不同的地球动力学环境中形成的，它们来自形成于不同岩石圈层的对比构造岩浆。因此，这两种金属的历史成矿学上揭示的差异具有合理的解释。碳酸盐岩几乎总是专门用于铌，而稀有金属伟晶岩和花岗岩则专门用于钽。这些类型的矿床是在完全不同的地球动力学环境中形成的，它们来自形成于不同岩石圈层的对比构造岩浆。因此，这两种金属的历史成矿学上揭示的差异具有合理的解释。碳酸盐岩几乎总是专门用于铌，而稀有金属伟晶岩和花岗岩则专门用于钽。这些类型的矿床是在完全不同的地球动力学环境中形成的，它们来自形成于不同岩石圈层的对比构造岩浆。因此，这两种金属的历史成矿学上揭示的差异具有合理的解释。