An olistostrome-mélange belt formed along a suture: Bornova Flysch zone, western Turkey

Aral I. Okay*, Ismail Işintek, Demir Altiner, Sevinç Özkan-Altiner, Nilgün Okay

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)

Abstract

The Bornova Flysch Zone (BFZ) in western Turkey is a regional olistostrome-mélange belt located between the zmir-Ankara Tethyan suture in northwest and the Menderes Massif in the southeast. The BFZ consists mostly of tectonized gravity mass flows. The blocks are Mesozoic limestone and ophiolite, which are enclosed in Cretaceous-Paleocene sheared sandstone and shale. The limestone blocks are of two types. The first type consists of Late Triassic to Cretaceous shallow marine carbonates. The second type has an Upper Triassic shallow marine section overlain by Jurassic to Cretaceous pelagic limestones. A semi-intact part of the platform occurs in the Karaburun peninsula and on the island of Chios. The ophiolitic blocks in the BFZ include ultramafic rock, gabbro, basalt and radiolarian chert of Middle Triassic to Cretaceous in age. The formation of the BFZ overlaps with the Cretaceous subduction and HP/LT metamorphism of the northern passive continental margin of the Anatolide-Tauride Block. This subduction zone was bounded in the west by a strike-slip tear fault. The BFZ formed in a narrow basin between this tear fault and the Tethyan ocean. The mass flows came from the southeast from the overriding ophiolite and accretionary complex, and from the northwest from the uplifted segments of the platform margin. This model provides an explanation as why the BFZ is unmetamorphosed, whereas the equivalent strata in the Menderes Massif were metamorphosed at depths of over 20. km. It also explains the prominence of gravity flows and the southward younging in the BFZ, and for the apparently anomalous observation that, although the Tethyan ocean lay to the northwest, the ophiolitic blocks are more common on the southeastern part of the BFZ. Regions away from the tear fault, such as the Karaburun peninsula, were least affected by subsidence and deformation during the Cretaceous and Paleocene.

Original languageEnglish
Pages (from-to)282-295
Number of pages14
JournalTectonophysics
Volume568-569
DOIs
Publication statusPublished - 28 Sept 2012

Funding

We thank Yıldırım Dilek, Andrea Festa and an anonymous reviewer for their detailed comments, which improved the manuscript. This study was supported by TÜBİTAK grant 103Y191 . Aral Okay also thanks TÜBA for additional financial support.

FundersFunder number
TÜBİTAK103Y191

    Keywords

    • Bornova Flysch Zone
    • Mélange
    • Mesozoic
    • Olistostrome
    • Stratigraphy
    • Turkey

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