Multi-phased uplift of the southern margin of the Central Anatolian plateau, Turkey: A record of tectonic and upper mantle processes

Abstract

Uplifted Neogene marine sediments and Quaternary fluvial terraces in the Mut Basin, southern Turkey, reveal a detailed history of surface uplift along the southern margin of the Central Anatolian plateau from the Late Miocene to the present. New surface exposure ages (10Be, 26Al, and 21Ne) of gravels capping fluvial strath terraces located between 28 and 135m above the Göksu River in the Mut Basin yield ages ranging from ca. 25 to 130ka, corresponding to an average incision rate of 0.52 to 0.67mm/yr. Published biostratigraphic data combined with new interpretations of the fossil assemblages from uplifted marine sediments reveal average uplift rates of 0.25 to 0.37mm/yr since Late Miocene time (starting between 8 and 5.45Ma), and 0.72 to 0.74mm/yr after 1.66 to 1.62Ma. Together with the terrace abandonment ages, the data imply 0.6 to 0.7mm/yr uplift rates from 1.6Ma to the present. The different post-Late Miocene and post-1.6Ma uplift rates can imply increasing uplift rates through time, or multi-phased uplift with slow uplift or subsidence in between. Longitudinal profiles of rivers in the upper catchment of the Mut and Ermenek basins show no apparent lithologic or fault control on some knickpoints that occur at 1.2 to 1.5km elevation, implying a transient response to a change in uplift rates. Projections of graded upper relict channel segments to the modern outlet, together with constraints from uplifted marine sediments, show that a slower incision/uplift rate of 0.1 to 0.2mm/yr preceded the 0.7mm/yr uplift rate. The river morphology and profile projections therefore reflect multi-phased uplift of the plateau margin, rather than steadily increasing uplift rates. Multi-phased uplift can be explained by lithospheric slab break-off and possibly also the arrival of the Eratosthenes Seamount at the collision zone south of Cyprus.