Geology And Geochemistry Of The Sanfengshan Cu-Au Deposit In Ruoqiang County, XinJiang, China

The Sanfengshan Cu-Au deposit in Xinjiang, China, is a VMS type deposit, hosted by LowerCarboniferous Hongliuyuan metavolcanic rocks. The deposit is geotectonically distributed alongthe southern margin of the Tianshan metallogenic belt. The sulphide mineralization occurs in twomajor alteration zones, represented by three distinct styles of mineralization; covellite-chalcopyrite-pyrite, covellite-chalcopyrite, and chalcopyrite-pyrite. The principal ore mineralsinclude pyrite and chalcopyrite associated with minor amounts of sphalerite, covellite, chalcocite,malachite and azurite; and gangue minerals consist of quartz, chlorite, calcite, jarosite andsericite etc. The sulphide ore body displays massive, disseminated, banded and brecciatedtextures.Hydrothermal alteration has strongly affected the host rock, with the intensity predominatelyincreasing towards the footwall rocks. It is dominated by chloritization, silicification,epidotization, pyritization near the orebody, and outwards followed by sideritization, albatization.The host metavolcanic rock is characterized by two alteration types: Chlorite±sericite±pyrite andChlorite±carbonateDue to hydrothermal alteration and metamorphism, the high field strength (HFS) elementsare considered useful in interpretating the petrogenesis of the host rocks. Major elementgeochemistry indicates subalkali basaltic composition, whereas trace elements data indicate twotectonic environment; island arc and mid oceanic ridge basalt.Research on the Sanfengshan can be dated back to the20thcentury; however, the ore genesisof the Sanfengshan Cu-Au deposit is not well defined. Based on the detailed study ofpetrological and geochemical characteristics of the Sanfengshan Cu-Au deposit, it is proposedthat the deposit is classified to the volcanogenic massive sulphide type.