Uranium metallogenesis of coarse grained granite in area H, China

The paper discusses uranium mineralization of magmatic genesis in a coarse grained granite. The mineralized matter mainly consists of dispersed uraninite, with pitchblende and other, undetermined black uranium minerals in minor amounts. The granite was crystallized from a uranium rich magma which has a lower REE content (175 ppm) and very low thorium content (7.6 ppm), and the Th/U ratio is only 0.05-2. Because the amount of REE rich accessory minerals in the granite is small, the uranium might be crystallized in the form of uraninite. Metallic mineral association can be divided into two groups, primary (uraninite, molybdenite, grained pyrite) and regenerated (amorphous pyrite, galena, pitchblende and relict black uranium minerals). The results of an isotopic study have proved that the formation of the surrounding rocks was no later than the Early Proterozoic. The host rock, granite, containing uranium mineralization has an age of 1700-1750 Ma. Through the study of the evolution of the isotopic system, the age of mineralization has been dated at about 1800 Ma. It indicates that uranium mineralization of the host rock are syngenetic. In addition, an age of reworking of about 300 Ma has been determined. (author). 8 refs, 11 figs, 9 tabs