Plio-Quaternary extensional tectonics of the Central Anatolian Plateau: a case study from the Tuz Gölü Basin, Turkey

Abstract

Abstract:The Tuz Gölü Basin is the largest sedimentary depression located at the center of the Central Anatolian Plateau, an extensive,low-relief region with elevations of ca. 1 km located between the Pontide and Tauride mountains. Presently, the basin morphologyand sedimentation processes are mainly controlled by the extensional Tuz Gölü Fault Zone in the east and the transtensional İnönü–Eskişehir Fault System in the west. The purpose of this study is to contribute to the understanding of the Plio-Quaternary deformationhistory and to refine the timing of the latest extensional phase of the Tuz Gölü Basin. Field observations, kinematic analyses,interpretations of seismic reflection lines, and 40Ar/39Ar dating of a key ignimbrite layer suggest that a regional phase of NNW–SSE toNE–SW contraction ended by 6.81 ± 0.24 Ma and was followed by N–S to NE–SW extension during the Pliocene–Quaternary periods.Based on sedimentological and chronostratigraphic markers, the average vertical displacement rates over the past 5 or 3 Ma withrespect to the central part of Tuz Gölü Lake are 0.03 to 0.05 mm/year for the fault system at the western flank of the basin and 0.08 to0.13 mm/year at the eastern flank. Paleo-shorelines of the Tuz Gölü Lake, vestiges of higher lake levels related to Quaternary climatechange, are important strain markers and were formed during Last Glacial Maximum conditions as indicated by a radiocarbon age of21.8 ± 0.4 ka BP obtained from a stromatolitic crust. Geomorphic observations and deformed lacustrine shorelines suggest that themain strand of the Tuz Gölü Fault Zone straddling the foothills of the Şereflikoçhisar–Aksaray range has not been active during theHolocene. Instead, deformation appears to have migrated towards the interior of the basin along an offshore fault that runs immediatelywest of Şereflikoçhisar Peninsula. This basinward migration of deformation is probably associated with various processes acting at thelithospheric scale, such as plateau uplift and/or microplate extrusion.