Correlation of major tectonic units from the Alps to Western Turkey

This contribution presents an extension of a previously published tectonic overview (http://pages.unibas.ch/earth/tecto/homepage/Schmid_etal_2008.pdf) into Greece and Western Turkey and discusses along strike similarities and differences. The Dinarides, linked to the Alps along the present-day Mid-Hungarian fault zone (a former transform fault), represent an orogen of opposite subduction polarity in respect to the Alps. The Dinarides and Hellenides consist of thrust sheets containing ophiolitic as well as Adria-derived continental material. These thrust sheets are located in a lower plate position in respect to an upper plate that is composed of the Tisza and Dacia Mega-Units (Dinarides) and Rhodopes (Hellenides), which have European affinities. These tectonic plates are separated by a Late Cretaceous- Early Paleogene suture zone (named Sava Zone), which represents that part of the Vardar Zone that stayed open until end-Cretaceous times and separates upper from lower plate in the Dinarides-Hellenides. This suture can be followed along strike all the way to the Izmir-Ankara suture zone. In the Dinarides and Hellenides parts of the ophiolites of the Vardar branch of the Neotethys Ocean (Western Vardar ophiolites) were obducted already during the latest Jurassic onto the Adriatic margin and were subsequently involved in Late Cretaceous to early Paleogene thrusting. This led to the formation of a series of composite nappes that consist of continent-derived material in their lower part and ophiolites in their upper part. During the latest Jurassic parts of the Vardar Ocean (Eastern Vardar ophiolites) were also obducted and thrust onto the European margin (i.e. the Dacia Mega-Unit), later to become part of an orogen with Europe-vergent structures. Our one-ocean concept does not require the presence of “terranes” separating various oceanic branches along the Neotethys margin, such as the Drina-Ivanjica block or the Pelagonian “massif”. Such continental units simply represent tectonic windows of the distal Adriatic margin, outcropping from below the obducted ophiolitic sheets referred to as Western Vardar Ophiolitic Unit. Moreover, there is no need for a separate ocean linked with Meliata-Maliac ophiolites, because these remnants simply represent the Triassic-age parts of the Vardar Ocean, preserved as imbricates below, or relics within, ophiolitic mélanges accreted in front of the obducted Western Vardar ophiolites. This one-ocean logic can be followed all the way from the Western Carpathians and Dinarides to the Peloponnesus and possibly into the Cycladic Islands. We find no evidence for a Pindos oceanic lithosphere either (i.e. for the so-called “Pindos Ocean”); the Pindos basin simply represents a pelagic seaway located in between carbonate platforms. Furthermore, the derivation of the protoliths of the Cycladic Blueschists, generally also attributed to the Pindos “Ocean”, from oceanic crust is questionable.
   By contrast, in Turkey ophiolite obduction clearly occurred during the Late Cretaceous rather than in Late Jurassic times which suggests a major change along strike locatedsomewhere between the Cycladic Islands and the Anatolian peninsula. Moreover, the Menderes massif, tectonically underlying the Cycladic Blueschists, does represent the eastern continuation of the Gavrovo-Tripolitza Zone rather than that of the Pelagonian zone. Another major along-strike change concerns the southeastern continuation of the Carpatho-Balkan orogen, which is considered a part of the Dacia Mega-Unit: the Rhodopes represent a part of the European margin that was northerly adjacent to the Vardar branch of Neotethys and that was subducted northward below Moesia and subsequently partly exhumed as a huge core complex surrounded by normal faults. Hence, it is not clear yet if the Rhodopes, or alternatively the lower part of them (Drama block), were formerly bordered by another branch of Neotethys, originally located to the north of Vardar branch, or alternatively, by the Paleotethys. In other words, the Rhodopes may have been formerly separated from Moesia by oceanic lithosphere located north of the Vardar branch of Neotethys.