| The Huanaote silver polymetallic deposit is a typical hydrothermal vein type silver polymetallic deposit in the Inner Mongolia-Xing 'an metallogenic area and the Bailianhupur-Jilin Baolige-Chaobuleng Paleozoic-Mesozoic copper,lead,zinc.gold.silver,tin and chromium(molybdenum)metallogenic belt in the Erlianhaote-Dongwuqi metallogenic belt.In this paper,the genesis of the deposit is analyzed from the aspects of ore-forming geological background,geophysical and geochemical characteristics,geological characteristics of the deposit,characteristics of ore-forming fluids and genesis of the deposit.The results are as follows:1.The results of field geological investigation,indoor petrographic identification and infrared spectrum analysis of altered rocks show that the main alteration types developed in the mining area include dolomitization,potassium silicification.chloritization,epidotization,pyritization and magnetite mineralization,among which dolomitization and Shi Ying-chlorite-pyrite mineralization are closely related to mineralization.The main metal minerals in the mining area include pyrite,arsenopyrite,sphalerite,galena,chalcopyrite,tetrahedrite,wheel ore,nagnetite,hematite,natural silver and silver-bearing sulfur minerals(silver tetrahedrite,silver-bearing tennantite),etc.Gangue minerals include Shi Ying,potash feldspar,plagioclase,carbonate minerals(calcite,rhodochrosite,siderite,etc.),chlorite,epidote.clay minerals,and rutile,monazite,xenotime,cassiterite,etc.2.The metallogenic stages of the mining area are systematically divided into five stages:?-K silicification stage;?-dolomitization stage;?-epidote-magnetite-Shi Ying stage;?-chlorite-carbonate-sulfide stage;?-ore-free carbonate stage.3.Through in-depth analysis of ore-forming fluids in the mining area,a large number of feldspar-Shi Ying crystal caves have been found in the fine-grained syenite in the area,indicating that the magma is rich in volatile matter.According to the petrography.microthermometry and LRM,LA-ICP-MS analysis of fluid inclusions in the Shi Ying of crystal cave,the fluid dissolved from magma is high temperature,medium salinity and CO2-containing fluid,and after fluid boiling,high salinity liquid phase and CO2-rich low density gas phase are produced,among which ore-forming metals rich in Pb,Zn,Sn,Mo,Bi and Ag are mainnly concentrated in the high salinity fluid phase The combination of metal elements in fluid inclusions is very consistent with the known mineralization types in the mining area,which further confirms the relationship between fine-grained syenite and mineralization in the mining area4.The alteration in the mining area has a certain distribution law.The alteration is generally weak in SE,gradually increasing to the west and north,and the alteration zone is generally distributed in NWW-near EW direction5.Put forward the understanding of the genesis of the deposit.Based on the comprehensive study of ore body characteristics,alteration law,rock and ore structure,mineral composition analysis results and fluid inclusion research results,it is considered that Huanaote Ag-polymetallic deposit is a hydrothermal deposits related to fine-grained syenite. |
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