Paleobathymetric evolution of the miocene deposits of Gombe and Aksu basins, Antalya, Turkey


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Geological Engineering, Turkey

Approval Date: 2018

Student: FATİH SEÇKİN ŞİŞ

Supervisor: NURETDİN KAYMAKCI

Abstract:

The Late Cenozoic Antalya Basins, located at the eastern part of the Beydağları Platform, within the Isparta Angle, unconformably developed on Mesozoic autochthonous carbonate platforms in the western Taurides. Aksu Basin developed in the inner part of the Isparta Angle and bounded by Aksu Thrust at the east. Gömbe Basin located at the western limb of the Isparta Angle and developed as a foreland basin in front of the Lycin Nappes on the Beydağları Platform. During their evolution, these basins experienced important bathymetric changes possibly due to vertical motions and variation in the sediment supply. This study provides a detailed analysis of paleobathymetic evolution of these basins. The conducted paleobathmetric study involves determination of the depositional depth of these basins by using foraminiferal fauna. It is based on the ratio of abundance of planktonic versus benthic foraminifera, which is related to the water depth. Percentage of planktonic foraminifera to total foraminifer population (%P) increases from shallow to deep water. However, some of the benthic foraminifera species are directly affected by the oxygen level of the bottom waters, rather than paleobathymetry, and are regarded as stress markers, hence they are discarded in the calculations of %P. In addition, carbonate dissolution of the foraminifera has the potential for miscalculations, since planktonic foraminifera are more prone to dissolution then the benthic ones. Nevertheless, recognition and determination of benthic species would be adequate for overcoming this complication. At the end, the obtained quantitative results must be verified and validated qualitatively using specific benthic depth markers. Depositional depth of the Aksu Basin were shallowing as a general trend, and rate of sedimentation exceeded the rate of subsidence in the middle part of the section. For most levels, calculated depths of Gömbe basins indicated depositional depths around thousand meters, contrary to the high sedimentation rates as indicated by turbiditic facies of the basin infills. Keywords: Paleobathymetry, Benthic Foraminifera, Foreland, Gömbe Basin, Aksu Basin.