内蒙古大兴安岭南段敖包吐铅锌银矿床成矿机制研究OA

[Objective]Aobaotu Pb-Zn-Ag polymetallic deposit has been newly discovered in the great xing'an range in recent years.Previous studies have evaluated the hydrothermal vein-type ore bodies controlled by fault structures,but the mechanism of lead-zinc-silver mineralization remains unclear and requires further research.[Methods]In this study,the formation age,material sources,and genetic mechanism of the deposit are systematically investigated via zircon geochronology,in-situ S-Pb isotope analysis,and H-O isotope measurement.[Results]The results show that:(1)The ore-forming parent rock yields a formation age of 156.7±2.5 Ma,which constrains the timing of mineralization to Late Jurassic.(2)In situ sulfur isotope characteristics reflect the magma source of sulfur.The in-situ Pb isotope characteristics reflect that Pb is a mixed source of crust and mantle,and it is a kind of mineralization closely related to magmatism from crust-mantle interaction.(3)Hydrogen and oxygen isotope studies indicate that the ore-forming fluids were dominated by magmatic-hydrothermal fluids in the early stage,with the addition of meteoric water in the late stage.[Conclusions]The Aobaotu Pb-Zn-Ag deposit was formed in the Late Jurassic.Granodiorite porphyry provided the source material for Pb-Zn-Ag mineralization,and the nearly E-W-trending faults and their secondary fractures are the main ore-hosting structures.This deposit is a fracture-controlled mesothermal magmatic hydrothermal vein-type deposit,associated with regional Late Jurassic tectono-magmatic-hydrothermal activity.