Critical elements (e.g., Li, Be, U) are essential for energy, technology, and national defense applications. Therefore, it is important to develop effective exploration strategies, understand how these deposits form, and develop genetic models for these deposits. The Baiyanghe deposit, China, is the largest Be-U deposit in Asia. Despite several recent studies, the age and sources of mineralization remain controversial. Petrographic and geochemical analysis of host rocks indicate that the Yangzhuang rhyolite is underlain by an evolved alkali rhyolite tuff, rhyolitic to dacitic tuff, andesitic tuff, and basaltic tuff units. We used the Sm-Nd and Sr isotopic compositions of ore-bearing and barren fluorite and the U-Pb isotopic compositions of uranophane-beta to date the Be and U mineralization precisely. Our results indicate that two stages of Be mineralization occurred at 311 ± 12 and 261 ± 3 Ma. Whole rock geochemical data suggest the Yangzhuang rhyolite (YR) and the felsic tuff members of the underlying Tarbagatay Group are the sources of Be and U. The Sr and Nd isotope data suggest the first stage of Be mineralization formed from Yangzhuang rhyolite-derived fluids while mantle-derived fluids mobilized the second stage of Be mineralization. Our U-Pb geochronology indicates uranophane is associated with primary Be mineralization at 305.3 ± 1.3 Ma and reported uraninite mineralization at 246.1 ± 1.3 Ma due to supergene processes.

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