2011 AGU Fall Meeting, San Francisco, United States Of America, 5 - 09 December 2011
Western Anatolia and the eastern Aegean demonstrate an interesting geologic history of horizontal and vertical tectonics. Active normal faulting and exhumational zones indicate that western Anatolia has experienced significant extension since the Oligocene-Early Miocene (~30 Ma). Geomorphological evidence indicates recent uplift: ~700 m in the last 3 Myrs. We have conducted a series of geophysical analyses to demonstrate that the region is also uplifted relative to an elevation that would be expected given an isostatic response to the lithospheric structure. Namely, topography 'residuals' indicate a residual uplift of ~1000 m over ~500 km sections of western Anatolia and the eastern Aegean. We also calculate admittance functions between free-air gravity and topography to quantify the nature of the uplift. These data indicate that the regional topography is isostatically uncompensated and is likely owing to an underlying mantle flow component. Heat flow data indicate that the area is thermally elevated as well. Using forward geodynamic modeling we consider idealized sections of Anatolian lithosphere based on tomographic inversions and examine the magnitude and pattern of surface topography and heat flow to reconcile with the geophysical observables. The models test the response of the surface topography to various configurations of the Anatolian-Aegean surface plates, including variably strong lithosphere and the presence of a weak mantle wedge and weak zones in the crust. Together, the geophysical data and analyses and modeling provide independent quantitative evidence that the thin Anatolian/Aegean lithosphere is being buoyed upwards by underlying mantle flow. We propose that the mantle flow is associated with lithospheric delamination beneath the region; a process that would also explain the ongoing crustal extension.