Global metallogeny of tantalum through geological time

Abstract

The distribution of tantalum-bearing mineral deposits and their tantalum resources are analyzed on the geological time scale. The sampling list includes 65 mineral deposits with their individual resource estimations above two thousand tonnes of Ta2О5. The used classification of the deposits includes five types: pegmatitic, granitic, alkaligranitic, foidic, and carbonatitic ones. Placers and ore-bearing weathering crusts are considered together with their endogenous hard ore sources. The geohistorical variability in tantalum metallogeny is presented through a comparison of supercontinent cycles. The Rodinian cycle gives the most significant amount of the resources with the lions share concentrated in exceptionally voluminous deposits of the foidic type. In descending order, it is followed by the Pangean and Columbian cycles, with the alkaligranitic and foidic types dominating in their resources. The Kenoran cycle, which is next in our resource ranging, stands out for its monotypic presentation, because only pegmatite tantalum deposits were generated in it. The current Amasian cycle has the smallest resource amount which is accounted for by the cycles incompleteness. The Amasian-aged resources are distributed between the alkaligranitic, granitic, and pegmatitic deposit types more or less evenly. In general, the pegmatitic and granitic types resources are of primary importance for tantalum extraction due to their mineralogical peculiarities. The pegmatitic type tantalum deposits were generated in all the cycles, while the granitic type objects were formed in the Pangean and Amasian cycles only. The most considerable resources concentrated in these two deposit types belong to the Kenoran and Pangean cycles.