Ore Formation Characteristics and Genesis of the Zhaishang Gold Deposit,Southern Gansu

Zhaishang gold deposit is a recently discovered large Carlin-type disseminated gold deposit,which is located in the western part of the Min-Li metallogenetic belt,wetern Qinling Mountains.Two main types of ore formation,namely,oxidized ore and primary ore,are recorded in gold ores.According to the differences of ore-host rocks,six types of primary ore formations can be distinguished:cataclasite,cataclastic carbonaceous slate,cataclastic silty slate,cataclastic carbonates,calcareous slate,and intense alternation breccia.Based on the characteristics of the primary ores,mineral assemblages in the gold ores can be divided into four types:assemblages I,represented by the association of minor sulfide-quartz,assemblages II,represented by the association arsenic-bearing pyritearsenopyrite-quartz,assemblages III,represented by the common association of polymetallic sulfide-quartz-scheelite-calcite,and assemblages IV,represented by the association minor sulfide-telluride-carbonate such as coloradoite,melonite,calcite,ankerrite,siderite.On the metallogenic process,deep origin(magmatic and/or metamorphic) hypothermal fluids may take a more important role in gold activation,though structural transition leads to gold and sulfides separate out from ore-forming by changing the conditions of the primary well-evolved fluids.The genesis belong to low and middle hydrothermal deposit.