Jurassic accretionary complex and ophiolite from northeast Turkey: No evidence for the Cimmerian continental ribbon

Abstract

Permian-Triassic and Late Cretaceous accretionary complexes, ascribed to the consumption of two distinct oceans, the Paleo-and Neo-Tethys, are exposed over extensive areas in the Eastern Mediterranean region. However, a separating continental ribbon, the so-called Cimmeride continent, between the Paleo-and Neo-Tethys during early Mesozoic time cannot be defi ned. Here we report a previously unknown Early Jurassic metamorphic oceanic accretionary complex and ophiolite from northeast Turkey, bounded by oceanic accretionary complexes of Permian-Triassic and Late Cretaceous age to the north and the south, respectively, without a continental domain in between. This special tectonic position and widespread coexistence of Permian-Triassic and Late Cretaceous accretionary complexes alongside the Izmir-Ankara-Erzincan suture imply that (1) the southern margin of Laurasia in the eastern Mediterranean region grew by episodic accretionary processes from late Paleozoic to end-Mesozoic time without involvement of a Cimmerian continental ribbon, and (2) the Paleo-Tethys and northern branch of the Neo-Tethys were not distinct oceans in the Eastern Mediterranean region.

40Ar-39Ar geochronology and petrogenesis of postcollisional trachytic volcanism along the İzmir-Ankara-Erzincan Suture Zone (NE, Turkey)*

“…Paleotectonic configurations of the southern part of the Pontides imply that the zone corresponding to the IAESZ was an old forearc mantle wedge at least since the beginning of the Mesozoic, which is documented by the overlapping subduction and accretion events Topuz et al, 2013;Delibaş et al, 2016;Gülmez et al, 2016). For that reason, the character of the mantle source area of the postcollisional magmatic units along the IAESZ was possibly dictated by highly metasomatized and subduction-related signatures even without any influence of an actively subducting slab, which has also been suggested by recent studies (Yücel et al, 2017).…”

Jurassic and Cretaceous radiolarian assemblages from the Bornova mélange in northern Karaburun Peninsula (western Turkey) and its connection to the İzmir–Ankara mélanges

“…Also in the Ankara region, plagiogranites that intruded pre-existing ophiolites were dated at 179 ± 15 Ma (Dilek & Thy, 2006). Finally, a Jurassic ophiolite was recently identified near in the İzmir-Ankara-Erzincan suture zone (Topuz et al, 2013) as well as Jurassic (150.5 ± 1.5 Ma and 150.0 ± 3.9 Ma) gabbros from the Eldivan ophiolite near Çankırı (Çelik et al, 2013). These Jurassic ages obtained within ophiolitic suites in Turkey are rather unusual and tend to confirm a close relationship between the Vardar Ocean and the İzmir-Ankara Ocean.…”

Outcrops, isotopic ages, terranes and the undesirable fate of tectonic interpretations

“…Just one example from the latter: Topuz et al (2012) recently claimed that the Cimmerian continent did not exist in northern Turkey because they could find no "continental basement" between the Palaeo-Tethyan and Neo-Tethyan accretionary complexes that they had dated. When one reads their paper, one realizes that by continent they mean an ancient gneissic/granitic basement.…”

“…Thus, there really are places in northern Turkey where the Cimmerian Continent is now absent (so their observation is in principle not new), but this is because of secondary removal by subsequent strike-slip faulting. Topuz et al (2012) consider this possibility and cite Şengör et al (2005), but seem to think that only a single big strike-slip fault can accomplish continental elision. Had they looked at Şengör et al (1993), they would have seen what a set of conjugate strike-slip faults can do in eliding large sections of colliding continents.…”