A PRE-CAMBRIAN OROGENIC MOSAIC IN NW ANATOLIA - TURKEY: A PASSAGE BETWEEN PAN-AFRICAN AND SOUTH EUROPEAN SUTURE ZONE

Northwestern Anatolian metamorphic massifs, known as Sünnice, Karadere, Almacýk and Armutlu, crop out as separate inliers exposed beneath a thick Paleozoic succession consisting of early Ordovician to Carboniferous clastics and carbonates. These metamorphic massifs underwent greenschist to amphibolite facies metamorphism before the Ordovician. As a result of the detailed geological mapping, the metamorphic massifs were differentiated into sub-units which include an ordered metaophiolite (Çele metaophiolite), an ensimatic island arc association (Yellice metavolcanics), continental crustal fragments (Demirci metamorphics), and a metagranitic association (Bolu granitoid complex).

Field relations, structural characteristics, and geochemical data obtained from representative lithologies of the massifs show that the Sünnice massif represents an almost a complete suprasubduction ophiolitic suite, composed mainly of an ordered ophiolitic foundation (Çele metaophiolite), and an ensimatic island arc association (Yellice metavolcanic association) developed ontop of the ophiolite. The Sünnice massif has all the members of the Precambrian units. However the continental fragments are not seen in the Almacýk and Armutlu massifs. The ophiolitic basement is not seen in the Karadere massif.

The ensimatic island arc complex was tectonically juxtaposed with a continental crust prior to deposition of early Ordovician sediments representing the first common cover.

The orogenic amalgamation is possibly related with the Pan-African orogeny suggesting that northwestern Anatolia formed a passage between the Pan-African and South European suture Zones, during that period.