Petrologic exploration criteria for magmatism-related uranium deposits: a review.

Magmatic rocks host different types of uranium deposits that can range from magmatic/high-temperature hydrothermal systems to post-magmatic, low-temperature hydrothermal deposits. The uranium mineralization in the syn- or late-magmatic systems could be divided into three types. (1) Magmatic deposits related to differentiated peralkaline complexes that are typically rich in SiO 2 (>72 wt%) and poor in (B: Fe+Mg+Ti)<100 (in cation values). The Na/K ratio in these rocks is > 1 and they have high contents of incompatible lithophile elements such as Nb, Ta, Zr, REE, Th and U. (2) Magmatic deposits related to strongly peraluminous magmas, derived from partial melting of crust. They are the result of a low degree partial melting of crustal arkosic (quartz-feldspathic) rocks with high SiO 2 (>74 wt%), low B < 40 and positive values for (A: Al-[Na+K + 2Ca]) (in cation values)), and are mostly accompanied by Li and F minerals. (3) Magmatic deposits related to the evolved hot peralkaline or metaluminous (A [A2] - to I- types) magma that assimilated fertile materials of the crust and endured a high rate of crystal fractionation. They mostly form high-temperature (vein-type and hybrid system) deposits. The rate of fluid in magma is important for the formation of this type of deposit. Therefore, the fertile magmas for this type of deposits typically have SiO 2 >72 wt%, positive values of A, B < 50 and K/Rb < 150. They are possibly rich in Mo and F. Dry-hot alkaline felsic volcanic rocks are more suitable for post-magmatic low-temperature hydrothermal deposits. The altered intrusive rocks with about 200 Ma age and higher contents of refractory minerals, are suitable candidates for supporting the post-magmatic, low-temperature hydrothermal uranium mineralization. [ABSTRACT FROM AUTHOR]

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