Characteristics Of Ore-forming Fluid And Significance Of Prospecting Of Luotuoshan Sulphur Polymetallic Deposit In Luanchuan, Western Henan

The Western Luanchuan County in geotectonic position is situated in the conjunction of the Southern margin of the North China Craton and the East Qinling fold system. This area has been found several large- super large porphyry-skarn type Mo-W-Pb-Zn-Ag deposit. Luotuoshan mining area is located on the North of Nannihu deposit, Luanchuan County. Main minerals of this area are pyrite and lead-zinc ore. This deposit that has relations with clastic rocks and carbonate rocks, Guandaokou Group and Luanchuan Group, is sulfide polymetallic deposit. Its ore body is mainly produced in skarn, layered distribution.Based on the regional geological achievements, this paper focused on field geological investigation, rock microscopic observation, microthermometry of fluid inclusions, laser Raman measurement and analysis, H-O isotopes and S isotope tracer to research the evolution process of the ore-forming fluids and deposit genesis characteristics of Luotuoshan sulfide polymetallic deposit.Through field geological investigation and rock slice observation, the mineralization period of time can be divided into two phases four stages.Skarn stage: early skarn stage, late skarn stage;Hydrothermal period: quartz- sulfide stage and carbonate stage.The mineralization period is divided into two period four stages. Skarn stage: early skarn stage, late skarn stage; Hydrothermal period: quartz- sulfide stage and carbonate stage. The results of microthermometry of fluid inclusions show that the early skarn stage ore-forming fluids are mainly in the environment which is high temperature, secondary salinity, low density, medium pressure, shallow depth; Late skarn stage ore-forming fluids are mainly in the environment which is midium-high temperature, lower salinity, low density, low pressure, shallow depth; Quartz- sulfide stage ore-forming fluids are mainly in the reducing environment which is high temperature, secondary salinity, low density, low pressure, shallow depth; Carbonate stage ore-forming fluids are mainly in the environment which is middle temperature, low salinity, small density, low pressure, near-surface.The results of H-O isotope and S isotope tracer show that the source of ore-forming fluid is the primary magma water, with gradual addition of meteoric water during their evolution; the source of ore-forming materials of sulfur is deep.With the passage of the ore-forming process, the salinity, temperature, pressure and depth of ore-forming fluid of Luotuoshan sulfide polymetallic deposit are on the decline.Immiscible(boiling) effect of fluid is the main reason of mineral deposits. And its genetic type is high temperature, secondary salinity, hypabyssal, bedded skarn deposit.Predicting the deposit have a low ore potential and the preliminary prospecting signs of such deposit are located in the mineralization transition zone of Nannihu or other metallogenic system in Luanchuan ore-concentrated area; Mineralized with skarn, K-feldspar, silicification, pyrite, carbonation; a large number of immiscible inclusion groups present in hydrothermal mineral quartz or fluorite.