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Uranium redox and deposition transitions embedded in deep-time geochemical models and mineral chemistry networks

February 9, 2024

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 U6+ mineral localities surpasses the number of U4+ mineral localities in the Paleoproterozoic. Moreover, the number of sedimentary U6+ mineral localities increases earlier in the Phanerozoic than the number of U4+ sedimentary mineral localities, likely due to the necessity of sufficient sedimentary organic matter to reduce U6+–U4+. Indeed, modeling calculations indicate that increased oxidative weathering due to surface oxygenation limited U4+ uraninite (UO2) formation from weathered granite and basalt. Louvain network community detection shows that U6+ forms minerals with many more shared elements and redox states than U4+. The range of weighted Mineral Element Electronegativity Coefficient of Variation (wMEECV) values of U6+ minerals increases through time, particularly during the Phanerozoic. Conversely, the range of wMEECV values of U4+ minerals is consistent through time due to the relative abundance of uraninite, coffinite, and brannerite. The late oxidation and formation of U6+ minerals compared to S6+ 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.

Publication Year 2024
Title Uranium redox and deposition transitions embedded in deep-time geochemical models and mineral chemistry networks
DOI 10.1029/2023GC011267
Authors Elisha Kelly Moore, J. Li, Ao Zhang, Jihua Hao, Shaunna M. Morrison, Daniel Hummer, Nathan Yee
Publication Type Article
Publication Subtype Journal Article
Series Title Geochemistry, Geophysics, Geosystems
Index ID 70251450
Record Source USGS Publications Warehouse
USGS Organization Geology, Energy & Minerals Science Center