Petrogenesis of highly differentiated I‐type volcanic rocks: Reinjection of high‐temperature magma—An example from Suolun silicic volcanic rocks, central Great Xing'an Range, China

Abstract

Silicic volcanic rocks are the main components of the upper crust. Understanding their genesis can help us better understand the processes of crustal growth, reconstruction, and crust–mantle interactions. In this study, we examine silicic volcanic rocks from Suolun in the Great Xing'an Range, China. These silicic volcanic rocks are of Cretaceous age (140–123 Ma), with 68–76 wt% SiO2, and the majority are of the high‐K (calc‐alkaline) series. εHf(t) ranges between +1.7 and +9.9, mostly around 7. The Early Cretaceous silicic volcanic rocks from Suolun are cold‐wet‐oxidised, highly differentiated I‐type volcanic rocks, and plagioclase and K‐feldspar are the main fractionation phases. TTiZ shows that silicic magma undergoes a reheating process in the magma chamber, which causes the early rheological lock‐up magma to reactivate and thus drives it to further differentiation. This process is probably driven by the injection of high temperature magma at depth. The wet upwelling of the Mongol‐Okhotsk Oceanic plate in the deep resulted in large‐scale magmatism in the area. These results provide a possible explanation for the formation of highly differentiated magmatic rocks and further confirm the evolutionary link between volcanic rocks and plutonic systems.