The Geochemical Characteristcs And The Cause Of Ore Deposit Formation In Yinchanggou-Qiluogou Lead-zinc Deposit, Ninnan, Sichuan

Yinchanggou-qiluogou Lead-zinc deposit situated in east of Xikang-Yunnan axis. The deposits occur in the dolomite of Sinian Dengying formation. The ore are stratiform and lode. The orebody is controlled by rupture, and have the characteristic of end to end alignment in both tendency and trend . ore mineral are sphalerite and galena, tetrahedrite , pyrite,white lead , et. al. Wall-rock alteration dominated by silicification and dolomitization. Through the study of the deposits, the following is conclusions summary:Lead and zinc element content characteristic: the main useful elements are Lead and zinc. Lead and zinc content of different location is different, some with zinc is given priority to, some lead is given priority to, the cue for hydrothermal ore-forming the differences. Test samples with zinc content found in obviously positive correlation, but fracture zone both content is higher, by structural fracture zone control obvious.Useful characteristics of beneficial associated elements: mineral rich associated element s: Silver, cadmium, gallium, Germanium, indium element is the comprehensive utilization of value.Rare earth elements features: ore, structure,and wall rock are enrichment light portion of rare earth, left the characteristics of high right low, rare earth content were higher. The different ores have differenceTrace element characteristic: through Cr - Co - Ni diagram analysis, found that samples of wall-rock are concentrated and different from of tectonite,altered rock,and ore。altered rock are distributed between tectonite and ore.ores have differences。Sulfur isotope characteristics: galena sphalerite all have heavy sulfur isotopes, combining the characteristics of regional paleogeography and related material, think deposits of sulfur source for the formation of sulphur.Carbon isotope characteristics: the characteristics of the carbon in ore are different from wall rock and altered rock.The carbon of ore have the characteristic of magma carbon or deep source carbon,while wall rock and altered rock's carbon has the characteristics of sedimentary carbonate.Hydrogen and oxygen isotope characteristics: the hydrogen and oxygen isotope of ore ,which have characteristics of magmatic water ,are different from wall rock and altered rock which have characteristics of metamorphic water.Lead isotope characteristics: Lead isotope of ore have obvious differences.There are anomalous lead In the previous test results . What are²⁰⁶Pb/²⁰⁴Pb-²⁰⁷Pb/²⁰⁴Pb,²⁰⁶Pb/²⁰⁴Pb-²⁰⁸Pb/²⁰⁴Pb,have positive correlation. Through comparing with rock in district,we discovered that△βvalue and△γvalue as well as huili formation,which prove that are related.Ore-forming fluid characteristics: inclusions polyphasic characteristics, with smaller early inclusions crystallization; Mineral crystallization relatively bulky, the late late into and CO2 composition more. Ore-forming fluid main composition is anion mainly Cl^-, SO₄^2-; Cationic mainly are Ca²⁺, K⁺, Mg²⁺ , and part of inclusion are halite and transparent mineral crystallization.Ore-forming temperature: early inclusions homogenization temperature 215～236℃; Late mineral homogenization temperature 122～184℃. Through observation by microscopy, discover reveal that the metallogenic temperature mineral features and special mineral, a variety of evidence that deposits belong to in low-temperature ore deposits.Metallogenic age: quartz vein hot activation HAESRDQ dating age from 109.3～5.8 Ma (late yanshan period - the Himalayan period).Organic matter plays an important role in ore-forming process. It can help migration of ore-forming materials, but also help carbonate sulfuric acid root ion reductive S2 -, provide the conditions with sulfide precipitation.Ore-bearing stratum constitute a special lithology which of physical and chemical environment are use for mineralize. The overlying strata of ore-bearing is Qiongzuosi formation is a good shielding effect; ore-bearing stratumb provides the favorable mineragenetic space;Guanyinya formation is a limitation on hydrothermal mineral infiltration. This is a set of combinations of lithology double fudge sundae type is in turn the geochemical ladder for oxidation characteristics (acidity) - a reduction (alkalescent) - reduction (alkaline) environment.To sum up,the features of Yinchanggou-qiluogou Lead-zinc deposit is magmatic water of mesothermal and epithemermal lead-zinc deposit..