Metamorphic imprint of ridge subduction on the Neo-Tethyan ophiolites from the Saka Unit (Central Pontides, northern Turkey)

Frassi, Chiara
Rebay, Gisella
Marroni, Michele
Sayıt, Kaan
Göncüoğlu, Mehmet Cemal
Ellero, Alessandro
Ottria, Giuseppe
Pandolfi, Luca
The Intra-Pontide suture zone is the northernmost ophiolite suture zone exposed in the Anatolian peninsula. It consists of several variably deformed and metamorphosed tectonic units derived from the Neo-Tethyan IntraPontide oceanic (IPO) basin, and its continental margins that are currently represented by the Istanbul Zonguldak and the Sakarya terranes. Recent data suggests that the IPO was a wide supra-subduction oceanic basin whose closure began in the uppermost Early Jurassic by a north dipping intra-oceanic subduction that divided the IPO into two different oceanic areas, namely IPO1 and IPO2. The Saka Unit is a small tectonic unit exposed in the eastern portion of the Intra-Pontide suture zone in the Central Pontides, which is interpreted as a tectonic melange produced during the intra-oceanic subduction that led to the closure of IPO1. The unit was affected by polyphase deformation and epidote-amphibolite facies metamorphism peak conditions experienced during the uppermost Middle Jurassic. Metamorphic studies and thermodynamic investigations constrain the peak pressure conditions to T approximate to 650-700 degrees C and P approximate to 0.9-1.3 GPa. These conditions reveal a 'hot' and anomalous geothermal gradient (15-22 degrees C/km) with respect to those of the other ophiolite-bearing units of the IntraPontide suture zone involved in the subduction. This anomalous gradient was herein attributed to the thermal pulse produced by the subduction of the IPO1 mid-oceanic ridge. The final re-equilibration occurred under greenschist facies conditions during the Early Cretaceous exhumation, when the oceanic lithosphere of the IPO was completely consumed and the continental collision between the Istanbul-Zonguldak and Sakarya terranes occurred.


Berber, Faruk; Sayıt, Kaan; Department of Geological Engineering (2021-12-27)
The Kösdağ Metavolcanics (KM) in the southern Central Pontides crops out between the Izmir-Ankara-Erzincan Suture Zone (IAESZ) in the south and the Sakarya Composite Terrane in the north. The unit is represented by a low-grade metamorphic assemblage including meta-basics, meta-intermediates, and meta-felsics, interlayered with recrystallized limestone, mudstone, and chert. While the unit is bounded to the north by the North Anatolian Fault Zone (NAFZ), the Dikmen Formation stratigraphically overlie the unit...
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Kaymakcı, Nuretdin; White, Stanley H.; van Dijk, Paul M. (2009-01-01)
The Cankiri Basin straddles the Izmir-Ankara-Erzincan Suture Zone which demarcates the former position of the northern branch of the Neotethys. It includes more than 3 km of pre-Middle Miocene in-fill related to late Cretaceous to pre-Middle Miocene evolution of the region. The basin has developed on the upper Cretaceous subduction complex and arc related basins of the Neotethys Ocean. The basin fill includes an upper Cretaceous forearc sequence overlain by Paleocene with a local unconformity. The upper Cre...
Tectono-stratigraphic and thermal evolution of the haymana basin, Central Anatolia, Turkey
Gülyüz, Erhan; Kaymakcı, Nuretdin; Department of Geological Engineering (2015)
The Haymana Basin is located on the southernmost tip of the Central Pontides and straddles between the İzmir-Ankara-Erzincan Suture Zone at the north and Intra-Tauride Suture Zone at the south. These suture zones designate the former positions of various branches of the Neotethys Ocean in Turkey, the basins evolved within these zones record the progressive closure of the Neotethys and the collision between Taurides, Kırşehir Block and Pontides during late Cretaceous to Eocene time interval. The Haymana Basi...
TOPRAK, V; Göncüoğlu, Mehmet Cemal (1993-12-01)
The Neogene-Quaternary Central Anatolian Volcanic Province (CAVP) is elongated in a north-east south-west direction within pre-Oligocene basement in central Turkey. This study investigates the field evidence relating to the development of the CAVP.
Late Cretaceous Volcaniclastics in NW Turkey
Boehm, Katharina; Wolfgring, Eric; Yılmaz, İsmail Ömer; Tüysüz, Okan; Wagreich, Michael (null; 2015-04-17)
On the southwestern coast of the Black Sea, in the western Pontides Upper Cretaceous tuff layers are present. The tuffs are intercalated with limestones, marls and turbidites and were investigated with focus on their geochemistry, to get new insights to the arrangement of terranes and ocean basins at this time. In the region two Upper Cretaceous volcanic units can be distinguished, separated by distinct red pelagic limestone successions, belonging to the Unaz Formation. The lower volcanic unit is named Dere...
Citation Formats
C. Frassi et al., “Metamorphic imprint of ridge subduction on the Neo-Tethyan ophiolites from the Saka Unit (Central Pontides, northern Turkey),” JOURNAL OF ASIAN EARTH SCIENCES, pp. 0–0, 2020, Accessed: 00, 2020. [Online]. Available: