How double-slab subduction shaped the Eastern Anatolian Plateau: Insights from geodynamic models

Abstract

The Eastern Anatolian Plateau presents a geologic puzzle: surface elevations of ∼2 km occur in an area with average crustal thickness (35−45 km) and thin mantle lithosphere (60−70 km). Despite various hypotheses proposing processes including slab break-off, delamination, and crustal shortening, the mechanisms behind the plateau’s formation remain debated. Geological reconstructions show Neotethyan subduction along two branches, but the role of one versus two slabs in the evolution of the plateau remains uncertain. This study addresses a key geodynamic question: Is the observed plateau evolution consistent with both single- and double-slab scenarios? We conduct high-resolution 2-D numerical experiments that test both scenarios. Our results reveal that a single-slab subduction model can produce a plateau with an average uplift similar to the observed data in terms of magnitude, but it fails to replicate the broadness of the plateau as observed today, stretching over a distance of 350 km. In contrast, in a double-slab subduction system, the northern branch of the Neo-Tethys first delaminates and breaks off before break-off of the southern branch, resulting in a topographic evolution that is better aligned with observations, including a southward-younging surface uplift of 2 km. This scenario also aligns more closely with geophysical and geological observations, including crustal deformation and subsurface structures seen in seismic tomography. Our findings suggest that the double-slab model provides a more coherent explanation for the development of the Eastern Anatolian Plateau. While this model is particularly applicable to the Tethyan orogenic system, it may offer insights into other regions with complex subduction dynamics such as India-Eurasia collision.