| The AoBaotu Lead-Zinc Mine is located in Kundu Town,AluKerqin County,Chifeng City,eastern Inner Mongolia.The geotectonic location is in the eastern section of the Xingmeng orogenic belt-the southern section of the Daxing'anling metallogenic belt.The Late Jurassic volcanic activity is strong in the area,and the ore body is in the Late Jurassic volcanic tuff.The ore-related rock mass is the Early Cretaceous granodiorite porphyry,the zircon U-Pb dating is 130.3±0.9Ma,and the Rb-Sr isochron of the sphalerite shows the ore-forming time of 130.6±2.3.Ma,the formation of the deposit is consistent with the age of the formation of the rock mass.Orebody occurs in vein-like structure fracture zone of nearly east-west and north-west direction.The ore mineral combination is mainly pyrite,galena,sphalerite,arsenopyrite,chalcopyrite.The gangue minerals are mainly quartz,calcite and sericite;the type of surrounding rock alteration of the deposit is mainly silicification and sericitization.carbonation.According to the relationship between the minerals,the mineralization stage of the deposit is divided into four parts:?1?quartz-pyrite ore phase;?2?fine-grained polymetallic sulphide stage,mainly galena,sphalerite,quartz generated,partially visible chalcopyrite;?3?coarse-grained polymetallic sulphide stage;?4?quartz carbonate stage.The geochemical analysis of the rock indicates that the granodiorite porphyry in the mining area is a calc-alkaline quasi-aluminous type I granite,which is enriched with large-ion lithophile elements and depleted with high field strength elements.The Sr isotope 87Sr/86Sr value is 0.7070.708,the Nd isotope?Nd?t?is-5.3-4.8,and the Hf isotope?Hf?t?is-5.54.6.The Sr-Nd-Hf isotope shows that rocks are crust-mantle mixed source.Through the microlithology of gangue minerals,Raman and temperature analysis of fluid inclusions,the deposits are H2O-CO2-NaCl system with medium temperature?concentrated at 220300??and low salinity?112.05%NaCleqv?.The C isotope?13C value of carbonate minerals is-8.4-4.8‰,indicating that the source of the material is deep magma source.The?18DV-SMOW value of quartz and late stage calcite in the early stage of mineralization is-108.18-47.82‰,and the value of?18OH2O is-4.925.85‰,indicating that the ore-forming fluids are mainly magmatic hydrothermal fluid in the early stage,and atmospheric precipitation is dominant in the later stage of mineralization.The S isotope?34S value of the sulfide in the deposit is 1.444.94‰,indicating that the sulfur is mainly magma source,the 206Pb/204Pb value of Pb isotope is18.10318.184,the 207Pb/204Pb value is 15.53415.614,and the 208Pb/204Pb value is38.13738.353,indicating that the ore-forming material is a mixed source of crust and mantle,and is consistent with the lead isotope range of the polymetallic deposit in the southern section of the Daxing'anling metallogenic belt.The in situ S isotope results?2.33-5.45‰?also show the characteristics of the magma source.The comprehensive study suggests that the formation of the Aobaotu deposit is related to the granodiorite porphyry.The formation period is the Early Cretaceous,the ore-forming rock mass and the ore-forming material have the same source.The deposit is a medium-temperature hydrothermal vein type deposit.The comprehensive study suggests that the formation of theAobaotu deposit is related to the granodiorite porphyry,and the formation period is Early Cretaceous.The ore-forming rock mass and ore-forming materials are mixed sources of crust and mantle.The deposit is a medium-temperature hydrothermal vein type deposit.The tectonic setting is an environment in which the ancient Pacific plate is subducted to the west and the plate is retracted. |
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