Chronology And Significance Of Detrital Zircon From Matrix Of The Melange,and Its Tectonic In Central Inner Mongolia

Lead and zinc deposit of Wulanbaiqi is located in the south of Bayinhua at Xi Ujimqin Qi in Inner Mongolia,and is a Medium-sized type lead-zinc deposit which werd discovered recently.Ore formation is mainly baiyingaolao strata of the Early Cretaceous,especially the Rhyolitic crystal tuff breccia containing debris,secondly is the muddy silt stone of higher Permian.The mainly ore bodies of ore section are dipping southward,their dip angles are 2⁴0°.Material source:the data of trace element showed that Ore bearing formation enriched more Ag?As?Bi?Cu?Mo?Pb?Zn element than the abundance of continental crust in eastern China,the enrichment coefficient K is between 3.96-54.74,which also shows that the Ore bearing formation have some of the ore-forming potential.The?³⁴S of the ore mineral is between-6.73^?0.17‰,the mean value is-3.96‰,which shows that the source of sulfur of this polymetallic deposit may come from the mantle,but the datas of?³⁴S is concentrate between-6^-4‰,so the sulfur may come from the stratum and mantle.The ²⁰⁶Pb/²⁰⁴Pb is between 18.12 8and 18.273,the ²⁰⁷Pb/²⁰⁴Pb is between15.486 and 15.549,the ²⁰⁸Pb/²⁰⁴Pb is between37.914³8.114,the lead isotope composition of ore deposits shows that the lead may come from the mixture of the mantle and crust.According to the analysis of micro-measurement of fluid inclusions,the fluid inclusions are mainly gas-liquid phrase inclusions.Homogeneous temperature of fluid inclusion are between 175⁴00?,the salinities w?NaCleq?are in the range of 2.9⁶.9%,the density are in the range of0.63⁰.944g/cm³,the pressure are between 8.2³2.2Mpa and the mineralization depths may between 0.4¹.1km.Therefore Ore-forming fluid is a typical solution of low salinity and low density.The potential stratum and the Secondary volcanic rocks of intermediate acid in Yanshan period have supply heat source and provenance,the EW fracture provide channels and reserve mine place for ore fluid migration.In a word,the deposit may be a typical intermediate-epithermal shallow lead-zinc polymetallic deposit which is related to magmatic activity.