Fig. 4: Plot of δD versus δ¹⁸O of apatite from Jurassic and Early Cretaceous granites in the NCC.

Shaded fields depict the isotope composition of continental crust, altered oceanic crust^10,54, metasomatized mantle I (SCLM)^9,10,86, and metasomatized mantle II (MTZ). The δD range of continental crust (−110‰ to −140‰) is derived from the data in this study. The δD range of the MTZ (−200‰ to −289‰) is estimated based on δD values of primitive melt inclusions in komatiites (−181‰ to −289‰), which are proposed to originate from the MTZ¹¹, and the lowest δD observed in granites in this study (~−200‰). Blue curves represent mixing trends between continental crust and metasomatized mantle I for the Jurassic granites. Orange curves represent mixing trends among continental crust, altered oceanic crust, and metasomatized mantle II for the Early Cretaceous granites. Dots on the curves represent 10% increments, and the ratio of hydrogen concentration in A to B (H_A/H_B) is indicated (cc: continental crust, ac: altered oceanic crust, mm1: metasomatized mantle I, mm2: metasomatized mantle II). Oxygen concentrations in all endmembers are assumed to be identical. Error bars of δD and δ¹⁸O represent internal precision of single analysis (2SE).