Origin and evolution of the Neogene Iskenderun Basin, northeastern Mediterranean Sea

Abstract Detailed interpretation of multichannel seismic reflection profiles and biostratigraphic data from exploration wells shows that the Iskenderun Basin evolved as a broad depocentre during the early Miocene between the tectonically active front of the Taurides in the west and northwest and the uplifted Kizildag–Hatay ophiolite complex in the south and southeast. The eastern portion of this large Miocene basin is represented in the subsurface of the Iskenderun Basin by two westerly dipping tilted wedges, which display progressive onlap to the east over the ophiolitic basement. This architecture suggests that they developed as growth strata wedges in a piggy-back basin on the trailing limb of a large easterly transported ophiolite thrust sheet. The well data show that the emplacement of this thrust sheet occurred progressively from the Serravallian to the upper Messinian. In the eastern portion of the Iskenderun Basin, the presence of the lower wedge in the footwall of the ophiolite-cored thrust culmination and the presence of the upper growth strata wedge of the upper subunit of Unit 3 onlapping the forelimb of the thrust culmination show that the main phase of thrust activity was initiated later in the Serravallian with uplift continuing to the Tortonian. The absence of Messinian evaporites over the crest of the culmination demonstrates that the structure was an erosive paleohigh in the Messinian. The absence of lowermost Pliocene strata in the eastern Iskenderun Basin suggests that this region remained emergent at that time, whereas deposition occurred without significant interruption to the west, over the backlimb portion of the culmination. The seismic and well data show that contractional deformation in the Iskenderun Basin had ceased prior to the development of the M-reflector as an erosional unconformity. The data further suggest that the transition between the late Miocene fold–thrust structures and the thick Plio–Quaternary succession along the northwestern margin of the Iskenderun Basin is defined by a fundamental angular unconformity, developed by deep erosion of the leading edge of the fold–thrust belt, as represented by the M-reflector. The Plio–Quaternary forms a thick, relatively undisturbed wedge, which shows east and south directed onlap over the northwestern flank of the Kizildag–Hatay ophiolitic basement high and the southeastern flank of the Misis fold–thrust belt. We infer that the Iskenderun Basin was primarily a Miocene intramontane depression that was passively filled during the Plio–Quaternary by predominantly deltaic sedimentation, with extensional faults providing minor accommodation space.