Long-Lasting Magmatic, Metamorphic Events in the Cathaysia Block: Insights from the Geochronology and Geochemistry of Inherited Zircons in Jurassic A-Type Granites

The Paleoproterozoic basement underlying the Cathaysia Block remains relatively understudied, and its contribution to the region’s tectonic evolution requires further investigation. In this study, we examined Jurassic Laiziling and Jianfengling A-type granites and identified a significant number of zircon grains exhibiting varied CL imaging characteristics. These zircons yielded four distinct age groups: <100 Ma, 200–100 Ma, 500–200 Ma, and >700 Ma. Detailed trace element analysis revealed that these age groups correspond to different zircon types: metamorphic recrystallized zircons (<100 Ma), primary magmatic zircons (200–100 Ma), and inherited zircons (500–200 Ma and >700 Ma). Through host rock and tectonic setting discrimination, we consider that the inherited zircons have host rocks of S-type granites and basic rocks, and these were formed in subduction-compression tectonic environments. In comparison to local significant geological events in history, we propose that these zircons record multiple tectonic events in the South China Block, including the amalgamation of the Yangtze and Cathaysia Blocks during the Neoproterozoic; an intracontinental orogenic event that occurred during the Middle Paleozoic; and subduction–exhumation processes related to the Paleo-Pacific slab; as well as extensional metamorphic events from the Cretaceous to Tertiary events. A comparison of Hf isotopic compositions revealed that zircons aged 500–200 Ma and >700 Ma share a 2.5–1.6 Ga crustal evolution zone, indicating that multiple re-melting events have occurred within the Paleoproterozoic basement of the Cathaysia Block.