Late Cenozoic surface uplift revealed by incision by the River Euphrates at Birecik, southeast Turkey

Incision by the River Euphrates has created a dramatic erosional landscape in the northern Arabian Platform in SE Turkey. We obtain accurate heights of its terrace deposits in the Birecik area using differential GPS, and summarise evidence regarding heights of Late Miocene basalt flows and low-altitude wetland sediments. We thus estimate ∼600 m of uplift since the early Late Miocene (∼9 Ma), represented by ∼270 m of fluvial incision, the difference reflecting downstream channel-lengthening as the coastline has retreated to the Persian Gulf, ∼1400 km away. The oldest recognised sediments, inset below this level, form a thick aggradation between ∼100 and ∼130 m above the present level of the Euphrates. We estimate that this accumulated during ∼5–3 Ma when uplift rates were low, such that aggradation was necessary to maintain a downstream channel gradient in response to the coastal retreat. Palaeolithic artefacts have been reported locally in Euphrates deposits up to ∼80 m above present river level, which we tentatively date to ∼1.8 Ma. The Euphrates subsequently incised to within ∼10 m of its present level before aggrading ∼45 m higher in the late Early Pleistocene. The final ∼55 m of incision reflects the increase in uplift rates observed worldwide in the early Middle Pleistocene, following the Mid-Pleistocene Revolution.