Permian re-melting and maturity of continental crust revealed by the Daqing peraluminous granitic batholith in Inner Mongolia

Zircon U-Pb dating was analyzed by laser ablation-inductively coupled plasma mass spectrometry in the Mineral Laser Microprobe Analysis Laboratory (Milma Lab), China University of Geosciences, Beijing (CUGB), following the methods described in Zhang et al. (2019). U-Pb data off-line reduction followed those procedures detailed in Andersen (2002), Ludwig (2003), and Liu et al. (2010). In-situ Hf isotope analyses were determined by multi-collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS) coupled with a NewWave 193UC excimer laser ablation system in the Milma Lab, CUGB. The detailed analytical processes were described by Wu et al. (2006). During these analyses, the 176Hf/177Hf of the Plešovice standard zircon was 0.282483 ± 20 (2SD, n = 12), within the error identical with the recommended value of 0.282482 ± 13 (2SD) reported by Sláma et al. (2008).Major elements were analyzed using XRF in the Institute of Geology and Geophysics, Chinese Academy of Science, Beijing. Analytical precisions are better than 2%. Trace elements were done on a high-resolution inductively coupled plasma mass spectrometry at the State Key Laboratory of Geological Processes and Mineral Resources (Radiogenic Isotope Geochemistry-RIG lab), CUGB. Precision for all trace elements was estimated to be 10% and accuracy is better than 5% for most elements based on repeated analysis (n=6) of the standard materials (GSP-2 and AGV-2). Whole-rock Sr-Nd isotopic compositions were conducted using Thermo-Finnigan Neptune plus MC-ICP-MS in the RIG lab, CUGB. The treatment processes followed Li et al. (2021) and reference therein. Instrumental mass fractionation was corrected using 86Sr/88Sr = 0.1194 and 146Nd/144Nd = 0.7219, respectively. The average measured 86Sr/88Sr ratio of the NIST SRM987 standard and 143Nd/144Nd ratio of the Alfa Nd standard were 0.710246 ± 14 (2SD, n=15) and 0.512420 ± 14 (2SD, n=15), respectively. These values are consistent with the long-term values of 86Sr/88Sr (0.710250 ± 27, 2SD) and 143Nd/144Nd (0.512423 ± 23, 2SD) obtained in this lab.