Abstract: Northwestern Anatolian orogen belt represent the accretionary belt of • pre-late • Triassicage, are deeply eroded so that the island arc, the subduction complex and the ophiolite sheets arenow only preserved beneath the post Late Triassic cover as metamorphic basement rocks,The Handeresi (Edremit) and Karasu (Bilecik) consist mainly of granodiorite and gren schist-greenstone complex which were generated as a consequence of closure of Paleo Tethyan by the northwarddipping subduction beneath the Pontian block. Granodiorite and green schist-green stone complex represents arc-trench systems of pre Late Triassic age, This deeply eroded arc complex (granodiorite) andsubduction complex, oceanic crust slices (green schist-green stone complex) overthrasted to the eachothers as dublex thrust system. Post erogenic elastic deposits of Late Triassic age overlay on the thrustbelts of granodiorite and green schist-green stone complex.This interpretation leads us to consider that western termination of the Paleo Tethyan suture locatedin the north west Anatolian accretionary belt.