Many granitoid plutons of Middle Jurassic age, arc plutonic in character, form a belt to the north of the paleo-Tethyan suture zone in northern Anatolia. These plutons are here called the Kastamonu granitoid belt. When they are interpreted in a regional geologic setting, it can be shown that they may be formed by the magmatism related to the northward subduction of paleo-Tethyan oceanic crust.