Whole-rock major and trace elements data, and whole-rock and carbonate isotope data, for the Nangqian potassic and ultrapotassic rocks. Whole-rock major and trace elements were measured at ISTerre, University Grenoble Alpes. For major elements, 50 mg of rock powder were digested in HF/HNO3 mixture at 90 during five days. Excess HF was neutralized using boric acid and solutions were diluted with 250 mL of Milli-Q water. Major element contents were measured by Inductively Coupled Plasma - Atomic Spectrometry (ICP-AES) in Grenoble using the method given in Chauvel et al. (2011, doi:10.1111/j.1751-908X.2010.00086.x). For trace elements, 100mg of rock powder were digested with a mixture of concentrated HF and HNO3 at 150 for at least two weeks in steer Spar bombs. Excess Hf was neutralized with HNO3, using cycles of acid addition/evaporation. 300 mg of a spike containing Be, Ge, In, Tm and Bi were added to an aliquot of the rock solution corresponding to 8 mg of the initial powder. The solutions were then evaporated, diluted with 2% HNO3 (+ 1 drop of HF), and analysed by Inductively Coupled Plasma - Mass Spectrometry. During measurement, the signal was calibrated using the reference material BR24 (Chauvel et al., 2011, doi:10.1111/j.1751-908X.2010.00086.x), which was run every 4 or 5 analyses. Quality of the analytical procedure was checked by analysing blanks, international reference materials (BHVO2, BEN, BCR2), duplicate solutions and multiple runs of solutions. Only elements with external reproducibility < 15% are given. The SARM-CRPG in Nancy and SEDISOR in Brest performed the whole-rock Sr and Nd isotope analyses. Results were normalized to values of 143Nd/144Nd = 0.512110 for JNd-I reference material and 0.511850 for LaJolla, and to 87Sr/86Sr = 0.710250 for the reference material NIST SRM 987. Blanks were 74 pg for Nd and 137 pg for Sr. ε-Nd(T) ratios were calculated using the CHUR isotopic composition of Bouvier et al. (2008, doi:10.1016/j.epsl.2008.06.010). Stable isotope analysis of carbonates was carried out in the stable isotope laboratory of Geoscience Rennes, CNRS-University of Rennes I. Carbonates in whole-rock powders were selectively dissolved at 50 with anhydrous phosphoric acid H3PO4. The released CO2 gases were collected using a cryogenic extraction line, and their isotopic compositions were analyzed by a VG Optima triple collector mass spectrometer. Results were normalized to the values of the laboratory in-house standard Prolabo Rennes and the international standard NBS18. The analytical uncertainty is ±0.2 for δ18O carb, and ±0.1 for δ13C carb.

999: below detection limit