Caledonian tectonic event of Cathaysia block: Constraints on zircon U-Pb geochronology and Lu-Hf isotope for two kinds of granite

Abstract: For better understanding the Caledonian tectonic event of Cathaysia block, this paper documents a set of new zircon U-Pb geochronological and Hf isotopic analytical results for the Caledonian massive and gneissic granites from Wuyishan-Jinggangshan area. Crystallization ages of gneissic granites range from 415 Ma to 440 Ma，crystallization ages of massive granites range from 430 Ma to 449 Ma. The εHf(t) values of zircons range from -20 to 0(n=247), most data below -10. The two stage Hf model ages (tDMC) range from 1.5 Ga to 2.8 Ga. Combined with previous data, the authors revealed that the formation age, zircon Hf isotopic form and two stage Hf model ages (tDMC) of the two kinds of granite are similar. Granites were derived from crustal source of different times, which recycled during Caledonian. In addition, the addition of juvenile mantle-derived magma was insignificant. The Caledonian tectothermal event of Cathaysia block took place within an intracontinental orogenic environment. Caledonian orogen may have transformed its tectonic regime at about 430Ma, and gneissic structure resulted from synorogenic or late-orogenic deformation.