Mediterranean snapshots of accelerated slab retreat: Subduction instability in stalled continental collision
Published:January 01, 2009
M. A. Edwards, B. Grasemann, 2009. "Mediterranean snapshots of accelerated slab retreat: Subduction instability in stalled continental collision", Collision and Collapse at the Africa–Arabia–Eurasia Subduction Zone, D. J. J. Van Hinsbergen, M. A. Edwards, R. Govers
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This review of Mediterranean geodynamics highlights that the Mediterranean region captures at a fortuitous moment in time, a picture of the fate of foundering, old, cold oceanic lithosphere of limited area due to being landlocked in an all-but-stalled continental collision (Africa with Europe). We synthesize the geological spatial and temporal data for stretched crust as well as the 3D distribution of old abyssal plains and new oceanic lithosphere segments in concert with heat flow, palaeomagnetic data, geodetic velocity data, earthquake hypocentre distributions and seismic tomography. We use three Mediterranean subduction system settings (the western Mediterranean, the Hellenic and the Pannonian–Carpathian) that nicely reflect the slab instability and retreat. We assume that mantle slab dynamics best explains the observations. The dispersal and segmentation of the foundering landlocked ocean results in a series of discontinuous subduction zones whose individual lengths gradually diminish while retreat accelerates as slab progressively narrow and tear (i.e. along-strike laterally-propagating slab break-off) due to imminent total consumption of available oceanic lithosphere. We suggest that the Mediterranean region offers a lucid series of snapshots of accelerated slab retreat that, additionally, is globally unique as the only present day example of what we term intra-collisional landlocked ocean subduction.
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Collision and Collapse at the Africa–Arabia–Eurasia Subduction Zone
The Mediterranean and northern Arabian regions provide a unique natural laboratory to constrain geodynamics associated with arc–continent and continent–continent collision and subsequent orogenic collapse by analysing regional and temporal distributions of the various elements in the geological archive. This book combines thirteen new contributions that highlight timing and distribution of the Cretaceous to Recent evolution of the Calabrian, Carpathian, Aegean and Anatolian segments of the Africa–Arabia–Eurasia subduction zone. These are subdivided into five papers documenting the timing and kinematics of Cretaceous arc–continent collision, and Eocene and Miocene continent–continent collision in Anatolia, with westward extrusion of Anatolia as a result. Eight papers provide an overview and new data from stratigraphy, structure, metamorphism and magmatism, covering the geological consequences of the largely Neogene collapse that characterizes the segments of interest, in response to late stage reorganization of the subduction zone, and the roll-back and break-off of (segments of) the subducting slab.