Hydrothermal Uranium Mineralization in the Tuyukan Ore Field (Northern Transbaikalia): Time of Precipitation of the Pitchblende and Age of the Uranium Source

Based on the study of local volumes of minerals using the classical methods of isotope dilution and thermal ionization mass spectrometry (U–Pb ID TIMS), an isotopic study of pitchblende and galena is carried out at the Natali uranium ore occurrence (Northern Transbaikalia). For the first time, it was shown that the pitchblende mineralization at the ore occurrence has a Late Silurian (422 ± 4 Ma) age. Its formation is related to the Early–Middle Paleozoic collisional tectogenesis in the area of the Tonod uplift, accompanied by increased fluid activity. The Pb isotopic composition analysis in galena associated with pitchblende show that galena is enriched in radiogenic isotopes ²⁰⁶Pb and ²⁰⁷Pb, a source of which was ancient (Precambrian) concentrations of uranium.