SHRIMP Zircon U-Pb Dating for Metarhyolites of the Kangbutiebao Formation at the Abagong Iron Deposit in the Southern Margin of the Altay,Xinjiang and Its Geological Significance

The Altay orogenic belt(AOB)is an important metallogenic belt in China,and situated in the middle part of the Central Asian Orogenic Belt(CAOB).Many economic deposits are distributed along the southern margin of the AOB,e.g.Kaktal Pb-Zn deposit,Mengku iron deposit,Abagong iron deposit,Tiemuerte Pb-Zn deposit,Keyinbulak Cu-Zn deposit,etc.,which all occur in the Kangbutiebao Formation stratum comprising low grade metamorphosed volcanic rocks.SHRIMP zircon U-Pb method yields a 412.6±3.5Ma(MSWD=1.4)age,representing the eruption time of the metarhyolites at the Abagong iron deposit.This age indicates that an intense volcanic activity may occur in the early Devonian in the Kelang basin at the southern margin of the Altay,suggesting an active continental margin setting during this time.