A Comparative Study Of The Saibo Copper Deposit And The Kekesala Iron-Copper Deposit In The West Tianshan,Xinjiang

Both the Saibo copper deposit and the Keksala iron-copper deposit are typical skarn deposits in the West Tianshan Mountains.Saibo copper deposit is located in the Yili micro-plate-Sailim block in the Tianshan tectonic belt.The ore bodies are mainly produced in the contact between the granodiorite porphyry and the Mesoproterozoic Jixian system Kusongmuqieke Group(Jxks)limestone.The mineralization characteristics of the deposit are characterized by rich pyrrhotite,a small amount of magnetite,no hematite,etc.,showing the characteristics of reductive mineralization.The Kekesala iron-copper deposit is located in the eastern part of the Boluokonu metallogenic belt in the Tianshan tectonic belt.The ore bodies are mainly produced in the contact between granodiorite porphyry with monzonitic granite and limestone with marble of Upper Ordovician Hudukdaban Formation(O₃h).Its metallogenic characteristics are characterized by a large amount of magnetite and hematite,and lack of pyrrhotite,showing the characteristics of oxidized mineralization.The ore-forming rock mass of the two deposits are both intermediate-acid,high-potassium,calcium-alkaline-calcalkaline,para-aluminous-peraluminous type I granodiorite and granite formed in a continental marginal arc environment.The ore-forming rock body of the Saibo copper deposit was formed in the Middle-Late Devonian,with the characteristics of high K₂O,low Th,high Sr and low Yb(Y).It was formed in a continental marginal arc environment,Mg^#=37?78,It is speculated that it was formed by direct melting of oceanic crust and was the product of contamination by mantle material and lower crust.The ore-forming rock body of the Kekesala iron-copper deposit was formed in the Late Devonian,with the characteristics of high K₂O,high Th,high Yb,and Y.Mg^#=34?70,formed in the continental marginal arc environment,presumed to be North Tianshan In the process of ocean subduction,the oceanic crust directly melts to replace the mantle wedge,forming high Sr low Y-type granodiorite.During the ascending process of the subduction zone fluid,the lower crust is partially melted to form felsic magma,which is the source of the mantle wedge.Basic magma mixed to form the main granodiorite and monzonitic granite.The ore-forming rock mass and ore-hosting strata of the two deposits are analyzed.The oxygen fugacity of the Saibo granodiorite porphyry ranges from FMQ+1.43 to FMQ+4.36 with an average of FMQ+2.34.The oxygen fugacity of Kekeala granodiorite ranges from FMQ-0.76 to?FMQ+3.65 with an average of FMQ+1.72;The oxygen fugacity of Kekesala monzonite ranges from FMQ-0.32 to FMQ+3.64 with an average of FMQ+1.14.The oxygen fugacity of the ore-forming rocks in the two mining areas is high,inheriting the characteristics of the magma source area.The oxygen fugacity of the metallogenic rocks in the two mining areas inherited the magma source area.Under the condition that the oxygen fugacity of the two ore-forming rocks is both high,the carbon-bearing strata result in the difference of oxidation reduction of ore-forming characteristics.The TOC content in limestone of Saibo copper deposit is 0.15-0.32%,and the TOC content in limestone of Kekesala iron copper deposit varies from 0.06-0.12%.The total organic carbon in limestone of Saibo copper deposit is more abundant than that in Kekesala.Organic matter in carbonaceous formation will be decomposed by heat,resulting in reducing gas,resulting in the decrease of environmental oxygen fugacity.