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.

Demir, T.; Seyrek, A.; Guillou, H.; Scaillet, S.; Westaway, R.; Bridgland, D.R.

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.

Citation

Demir, T., Seyrek, A., Guillou, H., Scaillet, S., Westaway, R., & Bridgland, D. (2009). 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, 68(4), https://doi.org/10.1016/j.gloplacha.2009.02.008

• Journal Article Type: Article
• Publication Date: 2009
• Deposit Date: Jul 7, 2010
• Journal: Global and Planetary Change
• Print ISSN: 0921-8181
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 68
• Issue: 4
• DOI: https://doi.org/10.1016/j.gloplacha.2009.02.008
• Keywords: Turkey, Eastern Anatolia, Pliocene, Pleistocene, Uplift, Basalt, K-Ar.