Geochemical Characteristics of Uranium-bearing Granite in Lantian Uranium Ore Field of North Qinling and Its Constraints on Uranium Mineralization

Lantian uranium ore field, as the most famous granitic-type uranium ore field in the north Qinling area, lies in the monzogranite of west Muhuguan granitic pluton.Systematic element geochemistry studies were carried out on the Muhuguan monzogranite by the authors. The results show that the Muhuguan monzogranite is highly rich in silicon, potassium, alkaline and differentiation peraluminous. In terms of trace elements, granite is richer in LILE such as Rb, U, La, Nd, Sm and deficient in Ba, Sr, P, Ti compared with primitive mantle. The distribution pattern of rare earth elements are rightward oblique with LREE enrichment. The uranium ore has similar REE characteristics with the monzogranite, suggesting that metallogenic material of the uranium deposit might come from the monzonitic granite. Although uranium content of the Muhuguan monzogranite is much lower than that of the general uranium-bearing granitic pluton, uranium existsin Muhuguan monzogranite in the form of active uraninite, which can be activated to migrate and then mineralize. Uranium, which exists in the form of uraninite, may play a more important role in the mineralization of granitic-type uranium deposits.