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The Neogene–Recent Hatay Graben, South Central Turkey: graben formation in a setting of oblique extension (transtension) related to post-collisional tectonic escape

SARAH J. BOULTON^*,, and ALASTAIR H. F. ROBERTSON

^* School of Earth, Ocean and Environmental Sciences, University of Plymouth, Fitzroy Building, Plymouth, Devon, PL4 8 AA, UK
School of GeoSciences, Grant Institute, Kings Buildings, West Mains Road, Edinburgh, EH3 9LP, UK

Author for correspondence: sarah.boulton{at}plymouth.ac.uk

Structural data and a regional tectonic interpretation are given for the NE–SW-trending Hatay Graben, southern Turkey, within the collision zone of the African (Arabian) and Eurasian (Anatolian) plates. Regional GPS and seismicity data are used to shed light on the recent tectonic development of the Hatay Graben. Faults within Upper Cretaceous to Quaternary sediments are categorized as of first-, second- and third-order type, depending on their scale, location and character. Normal, oblique and strike-slip faults predominate throughout the area. The flanks of the graben are dominated by normal faults, mainly striking parallel to the graben, that is, 045–225°. In contrast, the graben axis exhibits strike-slip faults, trending 100–200°, together with normal faults striking 040–060° and 150–190° (a subset strikes 110–130°). Similarly orientated normal faults occur throughout Upper Cretaceous to Pliocene sediments, whereas strike-slip faults are mostly within Pliocene sediments near the graben axis. Stress inversion of slickenline data from mostly Pliocene sediments at ten suitable locations (all near the graben axis) show that ₃ directions (minimum stress axis extension direction) are uniform in the northeast of the graben but orientated at a high angle to the graben margins. More variable ₃ directions in the southwest may reflect local block rotations. During Miocene times, the Arabian and Anatolian plates collided, forming a foreland basin associated with flexurally controlled normal faulting. During the Late Miocene there was a transition from extension to transtension (oblique extension). The neotectonic Hatay Graben formed during the Plio-Quaternary in a transtensional setting. In the light of modern and ancient comparisons, it is suggested that contemporaneous strain was compartmentalized into large-scale normal faults on the graben margins and mainly small-scale strike-slip faults near the graben axis. Overall, the graben reflects Plio-Quaternary westward tectonic escape from a collision zone towards the east to a pre- or syn-collisional zone to the west in the Mediterranean Sea.

Key Words: strike-slip faults • normal faults • Dead Sea Fault • East Anatolian Fault • Eastern Mediterranean • strain analysis • neotectonics