The Rožná uranium deposit (Bohemian Massif, Czech Republic): shear zone-hosted, late Variscan and post-Variscan hydrothermal mineralization

Magmatic and hydrothermal behavior of uranium in syntectonic leucogranites: The uranium mineralization associated with the Hercynian Guérande granite (Armorican Massif, France)

“…Wendt et al, 1979;Carl et al, 1983;Eikenberg, 1988;Cathelineau et al, 1990;Hofmann and Eikenberg, 1991;Kříbek et al, 2009;Velichkin and Vlasov, 2011 and references therein). Regarding the genesis of these deposits, Turpin et al (1990) proposed that in the Massif Central, the U deposition resulted from the mixing of two types of fluids: an oxidizing surface-derived aqueous fluid able to leach U from uranium oxides in the leucogranites and a reduced fluid with an inferred sedimentary origin.…”

“…Similarly, meteoric and basin derived fluids were involved during the genesis of the shear zonehosted U mineralization of Okrouhlá Radouň and Rožná in the Bohemian Massif (Kříbek et al, 2009;Dolníček et al, 2013) and their mixing likely promoted the precipitation of the U leached out from the basement. For the Schlema and Schneebergs vein-type deposits (Bohemian Massif), Barsukov et al (2006) showed that the U ore originated from the leaching of the cupola of the Aue syeno-monzogranite during the interaction with oxidizing hydrothermal fluids and that the reducing nature of the metasedimentary host rocks promoted the precipitation of U.…”

“…and this observation could suggest a mixing between a low temperature-low salinity fluid and a high temperature-moderate salinity fluid. A mixing process between meteoric-derived and basinal fluids has been invoked for the genesis of numerous uranium deposits of the EHB such as in the French Massif Central (Turpin et al, 1990) or Bohemian Massif (Kříbek et al 2009;Dolníček et al, 2013). For the Pen Ar Ran deposit, the low salinity of the fluid inclusions (1-6 wt.% eq.…”

Distribution and Origin of Clay Minerals During Hydrothermal Alteration of Ore Deposits

“…Illite-smectite mixed layer minerals together with kaolinite and chlorite are characteristic for argillized granitic rocks occurred in uranium ore deposits from the French Massif Central [3]. The temperatures, which were determined by chlorite thermometry in the Rožná, Okrouhlá Radouň and Vítkov II uranium deposits can be well correlated with temperatures obtained by study of fluid inclusions [10,20].…”

“…Total mine production of the Rožná-Olší ore district was 23,000 tons U with average grade of 0.24 % U. The Rožná uranium deposits is the last recently mined uranium deposit in Central Europe with annual production about 300 t U [10].…”