Late Oligocene\u2014Early Miocene shortening in the Thrace Basin, northern Aegean

Ümitcan Erbil,Aral I Okay,Aynur Hakyemez

doi:10.1007/s00531-021-02047-3

Ümitcan Erbil, Aral I Okay + Show 1 more

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https://doi.org/10.1007/s00531-021-02047-3

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Abstract

Late Cenozoic was a period of large-scale extension in the Aegean. The extension is mainly recorded in the metamorphic core complexes with little data from the sedimentary sequences. The exception is the Thrace Basin in the northern Aegean, which has a continuous record of Middle Eocene to Oligocene marine sedimentation. In the Thrace Basin, the Late Oligocene–Early Miocene was characterized by north-northwest (N25°W) shortening leading to the termination of sedimentation and formation of large-scale folds. We studied the stratigraphy and structure of one of these folds, the Korudağ anticline. The Korudağ anticline has formed in the uppermost Eocene–Lower Oligocene siliciclastic turbidites with Early Oligocene (31.6 Ma zircon U–Pb age) acidic tuff beds. The turbidites are underlain by a thin sequence of Upper Eocene pelagic limestone. The Korudağ anticline is an east-northeast (N65°E) trending fault-propagation fold, 9 km wide and 22 km long and with a subhorizontal fold axis. It is asymmetric with shallowly-dipping northern and steeply-dipping southern limbs. Its geometry indicates about 1 km of shortening in a N25°W direction. The folded strata are unconformably overlain by Middle Miocene continental sandstones, which constrain the age of folding. The Korudağ anticline and other large folds in the Thrace Basin predate the inception of the North Anatolian Fault (NAF) by at least 12 myr. The Late Oligocene–Early Miocene (28–17 Ma) shortening in the Thrace Basin and elsewhere in the Balkans forms an interlude between two extensional periods, and is probably linked to changes in the subduction dynamics along the Hellenic trench.

Highlights

The Aegean has been a region of major crustal extension in the Cenozoic related to the southward migration of the Hellenic subduction zone (Le Pichon and Angelier 1979; Jolivet et al 2013)
A suitable region to answer this question is the Thrace Basin in northern Aegean, which is a major sedimentary basin with sedimentation ranging from Middle-Late Eocene to Late Oligocene
We studied the structure and stratigraphy of the region north of the Bay of Saros, where one of the major folds of the Thrace Basin, the Korudağ anticline, is located (Fig. 2) with the aim of constraining the age and significance of the Late Oligocene–Early Miocene contractional deformation in the Thrace Basin

Summary

Introduction

The Aegean has been a region of major crustal extension in the Cenozoic related to the southward migration of the Hellenic subduction zone (Le Pichon and Angelier 1979; Jolivet et al 2013). A suitable region to answer this question is the Thrace Basin in northern Aegean, which is a major sedimentary basin with sedimentation ranging from Middle-Late Eocene to Late Oligocene The Soğucak Formation is overlain by a thick clastic sequence of Late Eocene to Late Oligocene age (Fig. 3; Kopp et al 1969; Sümengen and Terlemez 1991; Siyako and Huvaz 2007). We studied the structure and stratigraphy of the region north of the Bay of Saros, where one of the major folds of the Thrace Basin, the Korudağ anticline, is located (Fig. 2) with the aim of constraining the age and significance of the Late Oligocene–Early Miocene contractional deformation in the Thrace Basin

Methods

Conclusions