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Abstract:
Orogenic plateaus of continental collision zones exhibit landforms and fluvial networks
that retain first-order information on their topographic evolution and vertical growth. The inversion of
river longitudinal profiles allows to reconstruct the base level fall history of plateaus, supporting the study
of landscape evolution in the frame of geodynamic models. The Eastern Anatolian Plateau (EAP) of the
Arabia-Eurasia collision zone is a plateau at an early stage of development. It stands at ∼2,000 m, presents
endorheic basins, and is drained by three main river networks. Seismic data indicate a thinned lithospheric
mantle that explains the late Cenozoic volcanic activity. Despite the number of studies on the EAP uplift, its
history is still debated. In this study we investigated the EAP hydrography and topography, and we inverted the
longitudinal profile of one of the main rivers: the Arax River. The results describe a high-standing, low-relief
plateau drained by a hydrography, controlled by active tectonics. Longitudinal profiles and χ-plots illustrate
rivers in disequilibrium with channel steepness increasing downstream. The elevation of marine deposits
indicates a surface uplift of ∼2,000 m, ∼500 m of which are of residual topography. This upheaval occurred
by two increases: the first one at 10–11 Ma with the opening of a slab window and the arrival of a mantle flow
from Arabia and the second one at ∼5 Ma with the continued inflow coupled with isostasy. Our results describe
the early stage of collisional plateau development, distinguishing the contribution of deep processes and
isostasy to the topographic growth.
