J. Li Ao Zhang Jihua Hao Shaunna M. Morrison Daniel Hummer Nathan Yee Elisha Kelly Moore 2024 <p><span>Uranium (U) is an important global energy resource and a redox sensitive trace element that reflects changing environmental conditions and geochemical cycling. The redox 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 throughout Earth history. In this study, geochemical modeling using thermodynamic data, and mineral chemistry network analysis are used to investigate U geochemistry and deposition through time. The number of U</span>⁶⁺<span>&nbsp;mineral localities surpasses the number of U</span>⁴⁺<span>&nbsp;mineral localities in the Paleoproterozoic. Moreover, the number of sedimentary U</span>⁶⁺<span>&nbsp;mineral localities increases earlier in the Phanerozoic than the number of U</span>⁴⁺<span>&nbsp;sedimentary mineral localities, likely due to the necessity of sufficient sedimentary organic matter to reduce U</span>⁶⁺<span>–U</span>⁴⁺<span>. Indeed, modeling calculations indicate that increased oxidative weathering due to surface oxygenation limited U</span>⁴⁺<span>&nbsp;uraninite (UO</span>₂<span>) formation from weathered granite and basalt. Louvain network community detection shows that U</span>⁶⁺<span>&nbsp;forms minerals with many more shared elements and redox states than U</span>⁴⁺<span>. The range of weighted Mineral Element Electronegativity Coefficient of Variation (wMEE</span>_CV<span>) values of U</span>⁶⁺<span>&nbsp;minerals increases through time, particularly during the Phanerozoic. Conversely, the range of wMEE</span>_CV<span>&nbsp;values of U</span>⁴⁺<span>&nbsp;minerals is consistent through time due to the relative abundance of uraninite, coffinite, and brannerite. The late oxidation and formation of U</span>⁶⁺<span>&nbsp;minerals compared to S</span>⁶⁺<span>&nbsp;minerals illustrates the importance of the development of land plants, organic matter deposition, and redox-controlled U deposition from ground water in continental sediments during this time-period.</span></p> application/pdf 10.1029/2023GC011267 en American Geophysical Union Uranium redox and deposition transitions embedded in deep-time geochemical models and mineral chemistry networks article