Sources and petrogenesis of Late Triassic granitoids in the Yajiang gneiss dome group (eastern Songpan-Ganze orogenic belt) with tectonic implications

•Both S- and I-type granitoids occur in the Yajiang gneiss dome group.•The S-type granitoids originated from partial melting of metapelites.•The I-type granitoids possibly derived from partial melting of a complicated magmatic sources.•The granitoids were generated in the syn/post-collisional setting, indicating affinity between Songpan-Ganze and Yangtze.