Blueschist facies overprint of late triassic tethyan oceanic crust in a subduction–accretion complex in north-central anatolia, Turkey

Ömer Faruk Çelik*, Mutlu Özkan, Cyril Chelle-Michou, Sarah Sherlock, Andrea Marzoli, Alexey Ulianov, Iṡmail Emir Altıntaş, Gültekin Topuz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The late Cretaceous accretionary complex along the Iżmir–Ankara–Erzincan suture zone, northern Turkey, includes various types of metamorphic rock together with radiolarite, sandstone, mudstone, serpentinite, basalt and limestone. Metaplagiogranite blocks (up to 5 m in diameter) and a meta-gabbro slice (800 × 500 m) cross-cut by meta-plagiogranite are observed in a matrix of serpentinite, mudstone and radiolarian chert. These meta-gabbros and meta-plagiogranites show subduction-related geochemical characteristics. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons from two metaplagiogranites yielded 222.3 ± 1.5 and 227.2 ± 1.6 Ma crystallization ages. This study shows that the meta-gabbro and metaplagiogranite from the accretionary complex are remnants of the metamorphosed equivalents of the late Triassic lower crustal rocks of the subducted Tethyan oceanic crust. They are the oldest lower crustal rocks observed in the Iżmir–Ankara–Erzincan suture zone. Both the meta-gabbros and meta-plagiogranites have Na–Ca amphiboles, indicating blueschist facies metamorphism. However, phengites from a blueschist facies rock yielded an40Ar/39Ar age of 104.3 ± 0.7 Ma, indicating that blueschist metamorphism occurred during the Albian. All these data suggest that the oceanic crust formed during the Norian, metamorphosed during the Jurassic to early Cretaceous and then dismembered during accretionary complex formation in the late Cretaceous.

Original languageEnglish
Pages (from-to)945-957
Number of pages13
JournalJournal of the Geological Society
Volume176
Issue number5
DOIs
Publication statusPublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 The Author(s). Published by The Geological Society of London. All rights reserved.

Funding

We thank Rahmi Melih Çörtük, Ömer Altınbaşand Tuna Karataşfor their assistance during the field study. Raul Carampin (CNRPadova) is thanked for assistance during the electron microprobe analyses. Yıldırım Dilek, Okan Tüysüz and two anonymous reviewers are thanked for their valuable comments and suggestions, which improved our paper.. Funding The research presented in this paper was funded by the Scientific and Technological Research Council of Turkey (TÜBIṪAK) Project No. 112Y123. Funding The research presented in this paper was funded by the Scientific and Technological Research Council of Turkey (TÜBIṪ AK) Project No. 112Y123.

FundersFunder number
CNRPadova
Rahmi Melih Çörtük
TÜBIṪAK
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu112Y123

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