Uranium (U) is an important global energy resource and a redox sensitive trace element that reflects changing environmental conditions and geochemical cycling. The evolution of U mineral chemistry can be interrogated to understand the formation and distribution of U deposits and the redox processes involved in U geochemistry from deep-time to present day. In this study, mineral chemistry network analysis and U-minerals electronegativity associations based on the Pauling scale electronegativities of each mineral constituent element are used to investigate U geochemistry and deposition through time. Louvain network community detection shows that U⁶⁺ forms minerals with many more shared elements and redox states than U⁴⁺. However, U⁴⁺ occurs at a large number of mineral localities relative to the small number of U⁴⁺-minerals due to the abundant mineral species uraninite, coffinite, brannerite, and euxenite-(Y). Oxygen (O) is central in the network given that all known U-minerals contain O, while sulfur (S) is minor as there are no known U-sulfide minerals. The range of weighted Mineral Element Electronegativity Coefficient of Variation (wMEE_CV) values of U⁶⁺-minerals and minerals containing U with unknown redox state (U^U) both increase through time, particularly during the Phanerozoic. Conversely, the range of wMEE_CV values of U⁴⁺-minerals is consistent through time due to the abundance of uraninite, coffinite, brannerite, and euxenite-(Y). The majority of U-mineral species that occur throughout Earth history also occur during the time period from the early Triassic to early Cretaceous, when many abundant uranium deposits formed globally. The abundance of oxidized U⁶⁺ mineral localities increased much later during the Phanerozoic than oxidized S⁶⁺ mineral localities, indicating that S⁶⁺ was generated from oxidative weathering prior to U⁶⁺. The late oxidation and formation of U⁶⁺-minerals illustrates the importance of the development of land plants and redox-controlled U deposition from ground water in continental sediments during this time-period.

Daniel Hummer

Appearances