The western segment of the suture between the Yangtze and Cathaysia blocks: constraints from inherited and co-magmatic zircons from Permian S-type granitoids in Guangxi, South China

摘要

The location of the suture between the Yangtze craton and the Cathaysia block is uncertain in the west. Three proposed locations for the western segment of the suture all go through Guangxi but are up to 150km apart. Inherited zircon crystals from the Darongshan Permian S-type granitoid plutons, which are derived from the lower crust and occur north of the southernmost location for the suture, yield U-Pb ages with a major peak at 960Ma. The epsilon(Hf) (t) values of the inherited zircons with ages around the major peak vary from +6.4 to -23.4. The age distribution and Hf isotope variations of the inherited zircons are remarkably similar to those of Precambrian detrital zircon crystals from the western Cathaysia block but strikingly different from those of Precambrian detrital zircon crystals from the Yangtze craton. These results indicate that the western part of the suture is situated to the north of the Darongshan granitoid belt.