Akademik Veri Yönetim Sistemi
GLOBAL AND PLANETARY CHANGE, cilt.68, sa.4, ss.254-269, 2009 (SCI-Expanded)
Unspiked K-Ar dating makes the age of the Cakmakozu basalt in eastern Turkey 1818 +/- 39 ka (+/- 2 sigma). This basalt overlies a staircase of four terraces of the River Murat a Euphrates tributary, each separated vertically by similar to 20 m. We deduce from the relationship with the basalt that these fluvial deposits aggraded during successive similar to 40 ka climate cycles around the Pliocene-Pleistocene boundary (probably MIS 72-66). The incision and rock uplift at similar to 0.5 mm a(-1), thus indicated, are roughly consistent with the similar to 500 m of entrenchment of this similar to 1.8 Ma Murat palaeo-valley into a former lake basin since the Mid-Pliocene climatic optimum. We infer that the similar to 130 in of incision in this locality since similar to 1.8 Ma dramatically underestimates the associated rock uplift, estimated as similar to 600 m. The similar to 1100 m of rock uplift and similar to 800 m of surface uplift thus estimated since the Mid-Pliocene indicate (assuming Airy isostatic equilibrium) similar to 5 km of thickening of the continental crust, from similar to 37 km to the present 42 km. Eastern Anatolia was thus at a much lower altitude in the Mid-Pliocene than at present, consistent with 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. (C) 2009 Elsevier B.V. All rights reserved.