Petrogenesis of the Ke’eryin Li-rich granitic rocks and its implications for Li-mineralization in the eastern Songpan-Garzê Orogenic Belt, China

• The youngest magmatic activity in the Ke’eryin region was 205 Ma. • Late Triassic Li-rich granitic rocks were formed by melting of a metapelitic source. • The aplite and pegmatite record extreme fractional crystallization and the transition into a magmatic–hydrothermal. The Songpan–Garzê Orogenic Belt is a world-famous Li mineralization belt in China, but the petrogenesis and source of the Li-rich granitic rocks remain unclear. To address this issue, we investigated the Li-rich granitic rocks from the Ke’eryin, located in the eastern part of the Songpan–Garzê Orogenic Belt. Zircon U–Pb dating yielded crystallization ages for a two-mica granite (205 ± 1 Ma), aplite (204 ± 2 Ma), spodumene-free pegmatite (203 ± 1 Ma) and spodumene-bearing pegmatite (206 ± 2 Ma), indicating a roughly coeval magmatic-hydrothermal activity. Systematic decreases in Nb/Ta and Zr/Hf ratios, combined with negative correlations between CaO, Al 2 O 3 , P 2 O 5 , MgO, and SiO 2 , reveal progressive magmatic differentiation from granite through to aplite and finally the pegmatites. The distinct Sn enrichment in the spodumene-bearing pegmatite records a transition from an early H 2 O-poor to a late water-rich magmatic system. All rocks display elevated Rb/Sr and Rb/Ba ratios, along with uniform Sr–Nd isotopic signatures that resemble those of Triassic metapelites ( 87 Sr/ 86 Sr i = 0.703 ∼ 0.7148, ε Nd ( t ) = −11.2 ∼ −7.3). Therefore, the Ke’eryin Li-rich granitic rocks were generated through muscovite-dehydration melting of a metapelitic source, and progressive magmatic differentiation subsequently concentrated Li and other rare metals.