Sedimentation in a foreland basin within synorogenic orocline: Palaeogene of the Isparta Bend, Taurides, SW Turkey

Abstract

The Palaeogene Isparta Basin of southwestern Anatolia formed between two convergent arms of the Isparta Bend orocline of the Tauride orogen. The origin of this tightening orocline is hypothetically explained in plate-tectonic terms. Basin sedimentation commenced on a down-warped Mesozoic carbonate platform of a crustal block accreted at the end of Cretaceous to the southern margin of the Anatolian plate. The basin earliest deposits are Palaeocene reddish mudstones with a fossil-barren condensed basal part and increasingly interspersed with thin calcarenitic turbidites towards the top. The supply of turbiditic sediment to the basin plain subsequently increased, as the upper-bathyal basin plain became surrounded from both sides by a narrow littoral shelf with an advancing turbiditic slope ramp. A major forced regression occurred at the end of Bartonian, causing incision of subaerial to submarine valleys up 600 m deep, filled in with gravelly to sandy turbidites and debrisflow deposits during the subsequent rise of relative sea level. The half-filled valleys were re-incised due to a Rupelian forced regression and were fully filled with fluvio-deltaic bayhead deposits during a final marine transgression that re-established the basin-margin biocalcarenitic shelf. The littoral environment then expanded across the shallowing basin, as the basin axial zone was up-domed and eroded to bedrock level at the end of Oligocene and the basin was tectonically inverted in Miocene. The pattern of intra-orocline foreland sedimentation documented by this case study provides tentative criteria for the recognition of synorogenic oroclines and for their distinction from post-orogenic oroclines. © 2017 The Authors. Basin Research © 2017 John Wiley & Sons Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists