The temporal evolution of sanukitoids in the Karelian Craton, Baltic Shield: an ion microprobe U-Th-Pb isotopic study of zircons

Sanukitoid zircons have Th/U ratios above 0.5 and often higher, whereas nearby tonalite-tondhjemite-granodiorites (TTGs) have Th/U ratios below 0.5. Typically, tonalites are older than sanukitoids by more than 100 Ma and it is possible that tectonic processes associated with the collision of the Belomorian Mobile Belt provided the heat necessary to initiate the generation of the sanukitoid melts.