Neoproterozoic uranium mineralization in the Kangdian region of the eastern Tibetan Plateau, China

A Review of the Genetic Mechanism of Megacrystalline Uraninite in the Kangdian Region, China

“…It includes several tectonic units and prominent polymetallic belts containing abundant mineral resources. Therefore, the Kangdian region is an important mineral resource in southwestern China [14,[20][21][22]. The stratigraphy preserved in the outcrops in the Kangdian region is relatively complete, including Proterozoic to Quaternary strata [23][24][25][26][27][28].…”

“…Since the 1950s, hundreds of uranium occurrences have been discovered in the Kangdian region after more than 70 years of exploration and research. Uraninite was recovered from a high-grade metamorphic rock sequence and has been reported in IOCG (Iron Oxide-Copper-Gold) deposits observed in Na-rich metavolcanic and metasedimentary rocks, as well as in low-grade metasedimentary rocks in the Kangdian region [9][10][11][12][13][14]17,[32][33][34]. Migmatite-type uranium deposits in the western belt of the Kangdian region occur in a high-grade metamorphic rock sequence.…”

“…Felsic or albite veins that host mineralization intrude into the migmatite through faults or schistosities, appearing as veins, masses, and lenses. The boundaries between the ore-bearing veins and surrounding rocks are distinct, with little evident alteration of the surrounding rocks [9,14].…”

“…(1) Haita uranium occurrence (Table 1): Yin [35] calculated the formation age of the megacrystalline uraninite at the 2811 uranium occurrence to be 257.2 ± 4.9 Ma based on EPMA data. Additionally, the Nuclear Industry Beijing Geological Research Institute obtained ages of 799.2 ± 5.6 Ma (U-Pb isochron) and 782.8 ± 1.7 Ma (U-Pb isotope) for the megacrystalline uraninite and its associated titanite at the 2811 uranium occurrence [14]. Liu [37] reported three groups of Re-Os isotopic ages obtained from molybdenite coexisting with uraninite in felsic veins at the A19 uranium occurrence, with a weighted average age of 761 ± 19 Ma.…”

“…The most notable features of these occurrences are their large grain sizes, some up to centimeters in scale, and fully formed crystals. Naturally occurring uraninite of such a significant size is exceptionally rare, garnering widespread attention in industry and serving as a compelling research subject for investigating the genesis mechanism of megacrystalline uraninite [11][12][13][14]. This article systematically summarizes the formation age, conditions, relationship with migmatization, and metallogenic dynamic background of megacrystalline uraninite based on our team's research and a comprehensive review of previous studies.…”