A generalization of unpublished and published data since 1985 on biogeochemical, hydrogeochemical, geochemical, mineralogical studies and soil geochemistry at uranium deposits of the Khiagda ore field in the Vitim uranium ore district made it possible to reveal a genetic relation of deep cold carbonated hydrocarbonate–magnesium groundwater containing dissolved hydrocarbons (HCs) to uranium mineralization and ore preservation. The through penetration of epigenetic HCs was traced from the disintegration zone of basement granitoids through overlying sedimentary ore-bearing and volcanosedimentary rocks up to overlying fractured basalts. The assemblage of clarified rocks–HCs–siderites–uranium phosphates U(IV) was commonly found. Carbonated hydrocarbonate–magnesium groundwater and anomalous HC contents in soils can be additional criteria for identifying the Vitim-type uranium deposits in the Trans-Baikal region.