| Yangla copper deposit is located in the middle of Jinsha River tectonic belt,which is one of the most typical copper deposits in northwest Yunnan.based on sheep pull copper deposit prospecting pb-zn orebody of the newly discovered in recent years as the research object,in the gallery catalog and typical ore body,on the basis of detailed anatomy of pb-zn orebody geological features,trace elements and rare earth elements,sulfur isotope,lead isotope,zn isotopes,ore genesis and metallogenic material source and so on has carried on the detailed study,paper made the following conclusions and cognition:The lead-zinc bodies of Yangla deposit can be divided into two types,Skarn type lead-zinc ore bodies are distributed in the lower part of skarn type copper ore bodies in the form of layer,layer,vein and lens;The hydrothermal vein type pb-zn ore bodies are filled in the tectonic fracture zone in irregular veinlike manner.The main structures of Pb and Zn ores are disseminated structure,block structu-re,vein-net structure and lump(spot) structure,The ore structure mainly consists of metasomatism structure,idiomorphic crystal-other grain structure,fragmentation structure,crumpled structure,etc.The ore minerals are mainly sphalerite,galena,pyrite,and a small amount of chalcopyrite,pyrite,porphyry,etc.Gangue minerals are mainly calcite,quartz,etc.The formation of Pb-Zn ore body can be divided into the early and the late metallogenic stages.Lead-zinc ore in calcite can be divided into two stages,the early mineralization stage calcite(?) mainly shows its irregular shaped crystal crumb output,?REE in 24.05×10-6?104.50×10-6,the delta Eu display is abnormal,the delta Ce weak negative anomaly,rare earth element distribution patterns f or the enrichment of light rare earth the right type curve;Late mineralization stage calcite(?) in vein,?REE in 2 8.71×10-6?114.60×10-6,the delta Eu display is abnormal,the delta Ce weak negative anomaly,rare earth element distribution patterns for the enrichment of light rare earth the right t ype curve;There is no significant difference in the geochemical characteristics of rare earth elements in calcite in early and late metallogenic stages.The calcite in the lead-zinc ore body of Yangla deposit has the same REE source with skarn type copper ore,which comes from the mixing of granodiorite and surrounding rock(sandy slate,quartz sandstone,marble,etc.)Early mineralization stage calcite(?)?1 3CPDB between 6.52‰?4.07‰,the ?18O SMOW between 5.04‰?9.94‰,ore-forming materials are mainly derived from granitic magma;Late metallogenic stage calcite(?) ?13CPDB between 3.81‰?3.53‰,the ?18OSMOW between 14.36‰?17.30‰,ore-forming material comes from the granite magma with a mixture of Marine carbonate.Both stages of calcite are hydrothermal,the water-rock reaction and the coupling action of temperature reduction are the main controlling factors for the precipitation of hydrothermal calcite.The ?34S of sulfide in skarn Pb-Zn ore is between -2.48‰ and 2.32‰,the total sulfur isotope is close to zero,The metallogenic materials are derived from mantle and deep crust and belong to magmatic sulfur;sulfide Pb isotope 208Pb/204Pb=38.7501?38.7969,207Pb/204Pb=15.7159?15.7248,206Pb/204Pb=18.3640?18.3874.In ??-?? origin diagram,The lead isotope data are mainly projected in the lead range of the crust,indicating that the lead in skarn type lead-zinc ore body mainly comes from the upper crust.The value of Zn isotope ?66ZnJMC in the lead-zinc body of Yangla deposit is between 0.31 and 0.44‰,with an average value of 0.378‰,Zn-S isotope diagram shows that zinc isotopes are mainly derived from magma.There is no significant difference between the skarn type lead-zinc ore body and skarn type copper body in morphology,occurrence,ore-bearing position,mineral assemblage,ore composition,surrounding rock alteration,ore-controlling factors and C-O,S,Pb isotopes,It shows that the lead-zinc ore body and the copper ore body are of the same origin and are the products of the same metallogenic process,The lead-zinc ore body is later than the copper ore body,which is the product of the late metal-ogenic stage.Yangla skarn type lead-zinc ore body is of skarn origin and has no obvious difference from other typical skarn type lead-zinc deposits in China,The metallogenic pattern of lead and zinc in yangla deposit was established. |
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