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The Origin Of Metallogenic Material And Ore-forming Fluid In The Huize Super-Large Lead-Zinc Deposit, In The Northeast Of Yunnan Province, China

Posted on:2017-02-18Degree:MasterType:Thesis
Country:ChinaCandidate:L WangFull Text:PDF
GTID:2180330488464655Subject:Mineral prospecting and exploration
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The Huize superlarge lead-zinc deposit, which is located in the Sichuan-Yunnan-Guizhou Zn-Pb polymetallic mineralization belt in southwestern edge of the Yangtze platform, is one of famous and typical deposits in this zone. The deposit has special geological characteristics that ore grade is very high and symbiotic or associated useful components are rich and the ore-forming temperature is high and so on. Some barite veins have been found by field investigation, thus stage of mineralization was divided in detail for study of fluid inclusion. Samples about stratum of district were collected and analyzed for providing evidence of source of metallogenic material. On study of isotope geochemistry, this article discussed source and nature of ore-form fluid and source of sulfur. In above reseach, the conclusions are given out:(1) Barite veins are close to spacetime of Pb-Zn mineralization. They belong to Brt-Dol(Fe) second stage of early stages of hydrothermal mineralization period.(2) There are three types of barite-hosted fluid inclusions including gas-aqueous inclusions with rich aquaous(L+V)that are main type, gas-aqueous inclusions with rich gas(V+L), pure liquid inclusions(L). In study of barite fluid inclusions, ore-forming of early stage has medium-high temperature, medium-low salinity, medium-low density. The natures of fluid inclusions in different stage of mineralization show that from early stage to late stage,evolutionary process of ore-forming fluid is medium-high temperature, low salinity, high oxygen fugacity to medium temperature, medium salinity, low oxygen fugacity to medium-low temperature, medium-low salinity, low oxygen fufacity.(3) The metallogenic material mainly may be mainly derived from metamorphic basement, followed by sedimentary cover.Specifically, in the metamorphic basement, the Xiaohekou formation has a capacity to provide Zn and Ag and the Luoxue formation has acapacity to provide Ag; In the sedimentary, the Dingying formation has a capacity to provide Zn and Cd and the Qiongzhusi formation has capacity to provide Ag. The baizuo formation and Maping formation can provide Cd.(4) H-O isotope composition of barite shows that ore-forming fluid of early stage is metamorphic water and formation water, thus ore-forming fluid is deep fluid.C-O isotope composition of calcite shows that C in the ore-forming fluid is derived from dissolution of carbonate. C may be provided by stratum of carbonate in ore district. Isotope geological thermometer show that ore-forming temperature is 134℃~388℃. Sulfur isotopic composition of sulfide mineral show that 834SΣs of ore-forming is 14.44‰.δ34S of the barite forming in hydrothermal fluid is 20.14‰. They are close to sulfur isotopic composition of seawater sulfate, which surfur may be derived from marine evaporate in every stratum.Reduction mechanism of sulfate should be thermo-chemical sulfate reduction.
Keywords/Search Tags:stage of ore-forming, fluid inclusion, source of ore-forming material, source of ore-forming fliud, the Huize Pb-Zn deposit
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