Origin Of The Hudugeshaorong Compound Granite In Middle-South Great Xing'An Range And Its Significance For Mineralization

The middle-south Great Xing'an Range is a tin-polymetallic mineral deposit in northern China.In recent years,it has been an important research direction.The Cretaceous granite widely distributed in this area is closely related to the tinpolymetallic mineralization in this area.In recent years,a tin-zinc deposit has been discovered for the first time in the Hudugeshaorong composite granite body,which indicates that the early Cretaceous granite in this area may have good tin-polymetallic metallogenic potential,but there is still no study on the relationship between magmatic activity and tin-polymetallic metallogenesis.For this reason,this paper takes this rock mass as the research object,and discusses its diagenetic age,magmatic evolution and differentiation characteristics and tectonic background from the aspects of petrography,petrology,petrogeochemistry,zircon U-Pb chronology and Hf isotope geochemistry,so as to provide constraints for the mineralization of the rock mass.The main lithological characteristics of Huduge Shaolong composite granite are porphyry biotite granite,porphyry biotite monzonite,biotite granite,porphyry biotite syenite granite and granite porphyry.The main mineral assemblages are quartz,alkaline feldspar and plagioclase.Dark minerals are mainly biotite.The main elements are high silicon(71.11-77.01%),alkali-rich(7.53-8.70%),low calcium(0.66-2%)and magnesium(0.03-0.79%),with a high 10000*Ga/Al ratio(2.75-3.97),rich Rb(131.00-187.00),Sr(99.00-289.00),Ba(392.00-641.00),etc.Large ion lithophile elements,such as Nb(11.00-15.40),Ta(0.95-1.49)and Zr(48.00-134.00),are relatively deficient,and the negative anomaly of Eu is obvious(?Eu=0.09-0.42).The overall geochemical characteristics of A-type granites are characterized by distinct differentiation and evolution of granites.The evolution of magma and post-magmatic hydrothermal processes are tin,lead,zinc and silver polymetallic.The enrichment of elements provides constraints for mineralization in this area.Its LA-ICP-MS zircon U-Pb age ranges from 132 Ma to 137 Ma,and its zircon epsilon Hf(t)value is positive(+5.27~+8.47).Based on the dark inclusions found in the rock mass,it is inferred that the main material source is the Neoproterozoic-Early Paleozoic bottom-invading lower crust.Granite was formed in the extensional tectonic background,controlled by the process of lithospheric detachment and thinning,and the continuous evolution and differentiation of magma resulted in tin,lead,zinc and silver polymetallic deposits.