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Durham University

Department of Geography

Departmental Research Projects

Publication details

Demir, T., Seyrek, A., Guillou, H., Scaillet, S., Westaway, R. & Bridgland, D.R. Preservation by basalt of a staircase of latest Pliocene terraces of the River Murat in eastern Turkey evidence for rapid uplift of the eastern Anatolian Plateau. Global and planetary change. 2009;68:254–269.

Author(s) from Durham

Abstract

Unspiked K–Ar dating makes the age of the Çakmaközü basalt in eastern Turkey 1818±39 ka (±2σ). This basalt overlies a staircase of four terraces of the RiverMurat, a Euphrates tributary, each separated vertically by ∼20 m. We deduce from the relationship with the basalt that these fluvial deposits aggraded during successive ∼40 ka climate cycles around the Pliocene–Pleistocene boundary (probably MIS 72-66). The incision and rock uplift at ∼0.5 mm a−1, thus indicated, are roughly consistent with the ∼500 m of entrenchment of this ∼1.8 Ma Murat palaeo-valley into a former lake basin since the Mid-Pliocene climatic optimum. We infer that the ∼130 m of incision in this locality since ∼1.8 Ma dramatically underestimates the associated rock uplift, estimated as ∼600 m. The ∼1100 m of rock uplift and ∼800mof surface uplift thus estimated since theMid-Pliocene indicate (assuming Airy isostatic equilibrium) ∼5 km of thickening of the continental crust, from ∼37 km to the present
42km. Eastern Anatoliawas thus at amuch lower altitude in theMid-Pliocene than at present, consistentwith the low-relief lacustrine palaeo-environment. We infer that the subsequent development of topography and excess crustal thickness are being caused by coupling between surface processes and induced flow in the lower crust: climate change following the Mid-Pliocene climatic optimum resulted in faster erosion that has drawn mobile lower crust beneath the study region.

Department of Geography