Across-arc variation of the Famatinian magmatic arc (NW Argentina) exemplified by I-, S- and transitional I/S-type Early Ordovician granitoids of the Sierra de Velasco

►Velasco Ordovician granitoids reflect across-arc variation of Famatinian magmatism. ► Granitoids vary from I-type to S-type towards the continental interior. ► Transitional I/S-type granitoids occur between the I- and S-type granitoids. ► Granitoids formed by different degrees of mixing of mafic and metasedimentary melts.