Chronology, petrochemistry of fine grained granite and their implication to Mo-Cu mineralization in Xichong Mo deposit, Anhui Province, China

The Xichong molybdenum deposit is located in Yuexi County of Anhui Province, China, which is in the east end of Qinling-Dabie metallogenic belt. The intrusive rock in Xichong Mo deposit, from early to late, are quartz monzonite, fine grained granite (130.8 ± 1.1Ma) and bimodel dikes (including quartz syenite porphyry and lamprophyre) which are all Yanshanian magmatic products occurring in inner continental environment. The ore styles include vein style, stockwork and disseminated style, showing porphyry type mineralization characteristics. The well developed alterations include biotite-magmatite alteration, K-feldspar alteration, quartz-muscovite (sericite) alteration, silification, quartz-epidote alteration, chlorite-carbonate alteration and argillic alteration. The Cu-Mo mineralization is closely related to quartz-sercite and quartz-epidote alteration, and minor Cu mineralization is related to argillic alteration. The distribution of Cu-Mo mineralization and Cu-Mo geochemical abnormity is spatially related to fine grained granite which has high Mo content, and shows NW trend. The whole rock geochemical results of fine grained granite show peraluminous-metaluminous, high K calc-alkalic granite characteristics with a mixed mantle-crust origin. The fine grained granite has a similar intrusive age with bimodel dikes and implies a regional extention environment.