Nature 379, 785 - 790 (29 February 1996); doi:10.1038/379785a0

Geophysical evidence for lithospheric delamination beneath the Alboran Sea and Rif–Betic mountains

Dogan Seber^*, Muawia Barazangi^*, Aomar Ibenbrahim^† & Ahmed Demnati^‡

^* Department of Geological Sciences and Institute for the Study of the Continents, Cornell University, Snee Hall, Ithaca, New York 14853, USA
^† Centre National de Coordination et de Planification de la Recherché Scientifique et Technique, BP 1346, Rabat, Morocco
^‡ Office National De Recherches Et D'Exploitations Petrolieres, BP 8030, Rabat, Morocco

Geophysical evidence is presented for an episode of active delamination of a piece of continental lithosphere. Observations of earthquake hypocentre locations, seismic wave velocities and attenuation, Bouguer gravity, seismic reflection and drill hole data are combined with surface geology to infer the presence of a high-velocity, seismically active, rigid body in the upper mantle beneath the Alboran Sea and surrounding Betic and Rif mountain belts of the western Mediterranean region. This upper-mantle body, inferred to be the delaminating continental lithosphere, is overlain by a low-velocity, aseismic and strongly attenuating uppermost mantle, inferred to be the asthenospheric material replacing the delaminating lithosphere.

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