Petrogenesis of the Late Carboniferous Aolun granite in the southern Da Hinggan Mountains and its insight into the evolution of the Paleo-Asia Ocean

In this paper, zircon U-Pb age, geochemical characteristics study has been conducted on the Aolun granite, which is located in the Xing'an block.The granite is composed of quartz monosite and monzontic granite.The zircon U-Pb age of monzontic granite is 315.6±0.9 Ma, indicating that they are the the products of magmatic activity in the Late Carboniferous.The Aolun granite is enriched in Na(Na₂O=3.27%~7.24%), alkali(Na₂O+K₂O=8.19%~9.17%)and belongs to weakly peraluminous-strongly peraluminous granite(A/CNK=1.01~1.22).The granite has lower ΣREE, without pronounced negative Eu anomalies(δEu=0.62~0.93).It also enriched in some LILE(Rb, Th, K)and LREE, depletions Sr and different depletions HFSE(Ta, Nb, P, Ti).The granite is a I-type granite and belongs to the high K calc-alkaline series, and transitions to A-type granite.These features are similar to geochemical characteristics of continental crust composition.Combined with tectonic enevironment discrimination diagram, the Aolun granite is the product of the early stage post-orogenic extension, it is suggested that the region of the Paleo-Asian Ocean closed before the Late Carboniferous(315.6±0.9 Ma).