EPMA Monazite U-Th-Pb Chemical Dating for Monzogranites from Guangtoushan Intrusion in WesternQinlingMountains, Central China and Its Geological Significance
The Guangtoushan granitoid pluton consists of early quartz diorites, tonalities and late intrusive monzogranites. Early lithological assemblages were deformed during the collision event between the South China Craton (SCC) and the Qinling-Dabie Microblock (QDM); and some rocks of them have been partly changed into mylonites, which indicate that they were formed before the closure of Mianxian-Lueyang paleo-ocean basin. However, later stage S-type monzogranites emplaced into early quartz diorites and tonalities and the ductile shear zones as one main mark of the closure of Mianxian-Lueyang paleo-ocean basin, which reveals that the S-type monzogranites are correlated to the closure of the Mianxian-Lueyang suture zone. Therefore, the geochronological data of Guangtoushan granitic pluton can be used to constrain the timing of collision between the SCC and the QDM.