Abstract
We present a model for the dynamic formation of the forearc high of southern Anatolia where sedimentation in the forearc basin leads to thermally-activated deformation in the lower crust. Our thermo-mechanical models demonstrate that forearc sedimentation increases the temperature of the underlying crust by “blanketing” the heat flux and increasing Moho depth. Deformation switches from frictional to viscous with a higher strain rate led by increased temperature. Viscous deformation changes large-wavelength subsidence into coeval, short-wavelength uplift and subsidence. Models show that forearc highs are intrinsic to accretionary wedges and can grow dynamically and non-linearly at rates dependent on sediment accretion, sedimentation and temperature. The mechanism explains the uplift of the southern margin of the Central Anatolian Plateau and the Neogene vertical motions and upper-plate strain in the Anatolian margin along Central Cyprus. This system is analogous to forearc highs in other mature accretionary margins, like Cascadia, Lesser Antilles or Makran.
Highlights
Geodynamic processes are the first-order drivers of topography in orogenic plateaus and plateau margins
We present a model for the dynamic formation of the forearc high of southern Anatolia where sedimentation in the forearc basin leads to thermally-activated deformation in the lower crust
The mechanism explains the uplift of the Central Anatolian Plateau southern margin and the Neogene vertical motions and upper-plate strain in the Anatolian margin along Central Cyprus
Summary
Geodynamic processes are the first-order drivers of topography in orogenic plateaus and plateau margins. A different set of studies accounting for geological constraints and geophysical observables propose crustal thickening as an alternative mechanism to explain the uplift and elevation of the plateau margin (Fernández‐Blanco 2014; Fernández‐Blanco et al, 2019; Meijers et al, 2018; Walsh-Kennedy et al, 2014) The latter studies are based on reflection seismic data, field evidence and stable isotope paleoaltimetry estimates (Fig. 1C), and are compatible with the boundaries and short wavelength of margin uplift and seaward subsidence in South Turkey (~100 km from the deepest bathymetry to the highest topography). A forearc high grows dynamically and nonlinearly as an integral part of the accreting wedge and upper plate crust, seaward of any continental backstop This thermo-mechanical interplay reproduces the first-order spatiotemporal pattern of deformation and vertical motion across the SCAP, and the characteristic sequence of basin subsidence followed by forearc uplift at a shorter wavelength. This demonstrates that the mechanism of thermally-activated viscous flow, as proposed by Fuller et al (2006) and expanded here, is an important uplift mechanism that can be applied to the Anatolian margin and potentially be generalized to similar accretionary margins
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