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Coeval blueschist exhumation along thousands of kilometers: Implications for subduction channel processes
Géosciences Montpellier, UMR5243, Université Montpellier 2, CNRS, Place E. Bataillon, F-34095 Montpellier CEDEX 05, France
ISTeP, UMR7193, Université Paris 6, CNRS, Case 129, Tour 46-0, 2E, 4 place Jussieu, F-75252 Paris CEDEX 05, France
We herein focus on understanding what controls the detachment and migration of oceanic crustal slices along subduction zones. We provide evidence for the coeval Middle to Late Cretaceous exhumation of oceanic blueschists in the same Neotethyan subduction zone, across more than 3000 km, from depths around 30–40 km, over a short time interval (∼25 Ma) compared to the duration of subduction (>100 Ma). We stress the importance of such a geodynamic process and suggest that this exhumation was promoted by a regional-scale change in the long-term interplate mechanical coupling. On the basis of geological and geophysical evidence, we propose that the upward migration of oceanic fragments in subduction zones is normally inhibited and only occurs discontinuously, as the subduction channel opens up in response to a major change in plate geodynamics, slab geometry and dynamics, mantle wedge and slab hydration, or a combination of these.
Received 10 February 2009; accepted 19 May 2009; published 1 July 2009.
Citation: (2009), Coeval blueschist exhumation along thousands of kilometers: Implications for subduction channel processes, Geochem. Geophys. Geosyst., 10, Q07002, doi:10.1029/2009GC002428.
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