GEOCHRONOLOGICAL, GEOCHEMICAL, AND SR–ND–HF ISOTOPIC STUDIES OF THE QINGGELIHE A-TYPE GRANITES IN EASTERN JUNGGAR: IMPLICATIONS FOR ITS PETROGENESIS AND TECTONIC IMPLICATIONS

The Late Carboniferous–Early Permian magmatism of the Eastern Junggar region in the Central Asian Orogenic Belt provides a valuable geologic record that is critical for constraining geodynamic processes and unraveling the regional tectonic history. In this study, we report the zircon U–Pb ages and systematic geochemical data of the Qinggelihe granites in the northeastern part of the Eastern Junggar region (Xinjiang, northwest China) in the Late Carboniferous. The samples show a zircon U–Pb age of 307.7 ± 5.3 Ma, narrow ranges of SiO₂ (70.99–73.30 wt.%), Al₂O₃ (13.00–13.55 wt.%; A/CNK = 0.95–1.03), Na₂O+K₂O (8.12–8.79 wt.%), CaO (0.85–1.08 wt.%), and MgO (0.28–0.37 wt.%) contents, which are typical characteristics of A-type granites. The high positive εNd(t) (6.7–7.2) and εHf(t) (10.79–13.96) values, slightly low initial ⁸⁷Sr/⁸⁶Sr ratios (0.695985–0.709366), and young T_DM2 model ages (450–490 Ma), along with the depletion of Nb and Ta indicate that the Qinggelihe granites were derived from lower Dulate arc crust that inherited mantle characteristics. In addition, slab roll-back can account for the Late Carboniferous magmatic flare-up in Eastern Junggar. Combined with data from other exposed granites in Eastern Junggar and Chinese Altai, we propose that the Qinggelihe granites are the latest record of subduction in Eastern Junggar, and that the final collision between Eastern Junggar and Chinese Altai likely occurred between 307.7 and 304 Ma.