Characteristics And Significance Of Fluid Inclusions From Breccia Ore Of Getang Gold Deposit In Anlong,Guizhou Province

The Getang gold deposit is located in the typical Carlin-type gold deposits concentration area of tectonic activity belt-Youjiang orogenic belt,which is under Anlong jurisdiction of Guizhou Province.In this paper,quartz inclusions in breccia ores are taken as the research object to study the characteristics and origin of ore-forming fluid,source of ore-forming materials and the ore genesis of the deposit,According to these,the genetic type of the deposit has been determined and a metallogenic model has been preliminary established.The strata in the mining area is mainly dominated by Permian and Triassic,and the structures are dominated by fold and NE trending faults.The ore bodies are mostly stratiform,quasi bedded and lenticular.They occur in the structural altered rock on the karst unconformity surface of Longtan Formation and Mao Group.The ore bearing rocks are silicified breccia,and the alteration of the surrounding rock is mainly silicification.The output of ore bodies is controlled by interlayer gliding structure.Ore types are native ores and oxidized ores.The ore structures are mainly breccia structure,network vein structure,fine vein structure,disseminated structure and multi pore structure.Ore textures are mainly euhedral and subhedral granular texture,metasomatic structure,ring structure and contains structure etc..Ore minerals are mainly pyrite,pyrrhotite,arsenopyrite,stibnite.Nonmetallic minerals are quartz,calcite,fluorite,clay minerals and so on.The most important ore bearing minerals are pyrite and arsenopyrite,followed by clay minerals.The types of fluid inclusions are mainly gas liquid two phase,a small amount of pure liquid phase and pure gas phase.The homogenization temperature fluctuation of inclusions in ore is concentrated in the range of 120~150?and 170~200?centigrade.The average temperature is 146.82?indicating that there are two stages in the main metallogenic period of the Ge gold deposit.The range of freezing temperature fluctuation of inclusions is between-3.5~-0.1 and-1.8,and the mean freezing point temperature is-1.8?.The average salinity of inclusion is 2.98wt%,which is low salinity.The average density of ore-forming fluid is 0.95g/cm~3,and the average pressure of mineralization is 366.17×105 Pa,suggesting that the metallogenic depth is 0.60~1.91km.The ore-forming fluid density range is0.86~0.98g/cm~3,average 0.95g/cm~3,with medium and high density fluid characteristics,and the average metallogenic depth is 1.22km.The characteristics of the Au Au deposit are characterized by epithermal deposit,and the main metallogenic stage is related to the late Yanshan tectonic movement.The ore-forming fluids and ore-forming materials are complex,showing multi-sources and multi-periods.Deep mantle source and ore bearing formation are the main source of ore-forming materials.The source of ore-forming fluid is mainly magmatic hydrothermal fluid,and the thermal brine,basin formation water and meteoric water can form ore-forming fluid.The initial establishment of the metallogenic model:fracture deep fluid along the Youjiang basin formation and cracking many times of volcanic eruption of magma formed mixed fluid to transfer to the"Dachang layer"along the weathering surface into the layer slip structure,and metasomatic rocks and metamorphism,mineralization by the late extensional space and broken effect of low permeability rock combination,forming zone type mineralization,mineral precipitation and enrichment.