JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, vol.117, 2012 (SCI-Expanded)
The Western Anatolian and Aegean region demonstrates a complex geologic history of
horizontal and vertical tectonics. Active normal faulting and exhumation zones indicate
that Western Anatolia has experienced significant extension since the Oligocene-Early
Miocene (30 Ma). Our geophysical analyses demonstrate that the region is also uplifted
relative to an elevation that would be expected given an isostatic response to the
lithosphere structure. Namely, topography “residuals” indicate a residual uplift of about
1500 m over 200 km sections of Western Anatolia and the Aegean. Admittance functions
between free-air gravity and topography indicate that the regional topography is
isostatically uncompensated and as it approaches 50 mGal/km at the longest
wavelengths, the uncompensated topography is likely owing to an underlying mantle flow
component. Using forward geodynamic modelling we consider an idealized section of
Western Anatolian lithosphere based on tomographic inversions and examine the
magnitude and pattern of surface topography to reconcile with the geophysical
observables. The models consistently show a plateau-type uplift (and horizontal extension)
through Western Anatolia with an amplitude and wavelength consistent with the residual
topography calculations. Together, the geophysical analyses and modelling provide
independent quantitative evidence that the thin Anatolian-Aegean lithosphere is being
buoyed upwards by underlying mantle flow. The mantle flow may be associated with
active lithosphere delamination beneath the region; a process that would also explain the
ongoing crustal extension.