Zircon ages and Hf isotopic compositions of Permian and Triassic A-type granites from central Inner Mongolia and their significance for late Palaeozoic and early Mesozoic evolution of the Central Asian Orogenic Belt

摘要

This work presents zircon ages and Hf-in-zircon isotopic data for Permian and Triassic A-type granitoids and reviews the evolution of central Inner Mongolia, China, during the early Permian and Late Triassic. SHRIMP U-Pb dating of zircons of peralkaline granites yielded Pb-206/U-238 ages of 294 +/- 4Ma and 293 +/- 9Ma that reflect the time of Permian magmatism. Zircon ages were also obtained for Late Triassic granites (226 +/- 4Ma, 224 +/- 4Ma). Our results, in combination with published zircon ages and geochemical data, document distinct magmatic episodes in central Inner Mongolia.