ORE-CONTROLLING CHARACTERISTICS OF THE DIAOSHUIDONG MICRO-GRAIN DISSEMINATED TYPE OF GOLD DEPOSIT IN HUNAN PROVINCE

The Diaoshuidong micro-grain disseminated type of gold deposit is situated in the middle of Baimashan-Longshan E-W-trending metallogenic zone.The Banshan formation of Devonian System unconformally overlaps on Sinian and Cambrian Systems.A 20-350 m wide and more than 5 km long brittle-ductile shear zone is developed on the northeastern wing of the NW-trending basement uplift.The ore-bearing rock occurs mainly as pelitic siltstone in the third member of Banshan formation.The Au-bearing alterations,represented as decolourization,silicification and pyritization,are distributed along the NW-trending brittle-ductile shearing zone.The gold orebodies occur as buried or semi-buried bedding,lenticular and vein type in the alteration zone.The ore presents mainly as oxidized altered pelitic siltstone.Pyrite is the major Au-bearing mineral.The deposit is controlled together by lithology and structure.The Sinian and Cambrian basement strata are the main metallogenic material resources. Magmatic activities have contributed heat and part of metallogenitic material.The third member of Banshan formation is favorable for the migration of ore-forming fluid and enrichment of Au. The special sedimentary type is advantageous for Au metallogenesis.The basement tectonic and dome structure spatially control the distribution of gold deposit.The NW-trending basement uplift and brittle-ductile shear zone controlled the distribution of Au-bearing alteration zone,while the NW-trending brittle faults control the orebodies.The region has a great prospecting potential for gold deposits of the same type.