Seismic Tomographic Imaging of the Eastern Mediterranean Mantle: Implications for Terminal Stage Subduction, the Uplift of Anatolia, and the Development of the North Anatolian Fault
Abstract
By studying the mantle below the the Eastern Mediterranean, one can study a unique east-west transition from active subduction of Earth's oldest oceanic lithosphere to continental collision. Hypotheses concerning asthenospheric- and subduction-related processes have been invoked to explain the region's ∼2km uplift and Miocene volcanism, but their relative significance is debated. To address these issues, in Kounoudis et al., (2020) we present new P- and S-wave mantle seismic tomographic models that reveal fast anomalies associated with an intact Aegean slab in the west, progressing to a fragmented, partially continental, Cyprean slab below central Anatolia. Our models illuminate a gap between the Aegean and Cyprean slabs, and a horizontal tear in the Cyprean slab below the Central Anatolian Volcanic Province. Below eastern Anatolia, the detached 'Bitlis' slab is a fast wave-speed anomaly at ∼500km depth. Assuming slab sinking rates resemble Arabia-Anatolia convergence rates, the Bitlis slab's location suggests an Oligocene (∼26Ma) break-off. Results further reveal a strong velocity contrast across the North Anatolian Fault, likely resulting from a 40−60km decrease in plate thickness from the Precambrian lithosphere north of the fault to a thinned Anatolian lithosphere in the south. Slow shallow-mantle velocities below active volcanoes in eastern Anatolia, and ratios of P- to S-wave relative travel-times, indicate a thin lithosphere and melt contributions. Positive central and eastern Anatolian residual topography requires additional support from hot/buoyant uppermost mantle to maintain the observed 1−2km elevation, in addition to an almost absent lithospheric mantle. Small-scale fast velocity structures in the shallow mantle above the Bitlis slab may therefore be 'drips' of Anatolian lithospheric mantle.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMDI0150017B
- Keywords:
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- 3914 Electrical properties;
- MINERAL PHYSICS;
- 3621 Mantle processes;
- MINERALOGY AND PETROLOGY;
- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS;
- 8159 Rheology: crust and lithosphere;
- TECTONOPHYSICS