Origin of Late Paleogene to Neogene basalts and associated coeval felsic volcanic rocks in Southwest Hokkaido, northern NE Japan arc: Constraints from Sr and Nd isotopes and major- and trace-element chemistry

► Analyses of Sr and Nd isotopes, and major- and trace-elements of volcanic rocks. ► Temporal variation of Sr and Nd isotopic ratios of basalts. ► Temporal isotopic change of source mantle. ► Heating of the lower crust by basalt magmas derived from mantle. ► Production of felsic magmas from lower crust by partial melting.