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Seber, D., Barazangi, M., Ibenbrahim, A., and Demnati, A.
Geophysical evidence for lithospheric delamination beneath the Alboran Sea
and Rif-Betic mountains
Nature, 379, 785-790, 1996.
Abstract
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.
Copyright Statement
This paper was published in Nature by the Nature Publishing Group (NPG), and
NPG retains the copyright.
Link
to Nature
Key Figures and Captions
Figure 5. (a) Interpreted geological cross section between
the Rif and Betics. This north-south oriented cross-section represents the inferred
structures as well as topographic and gravity profiles along 5°W longitude.
Seismicity shown (circles with standard errors) is between 2° and 6°W
longitude. Continental lithosphere beneath both the Rif and Betics are delaminating.
Base of the lithosphere in each region is not well constrained. As the lithosphere
peels off from the overlying crust, low-velocity, low-Q asthenospheric material
rises up and replaces the lithosphere, especially beneath the Alboran and Rif
regions. Also shown are velocity variations (in percent) obtained by teleseismic
tomography. (b) Schematic representation of the evolution of the lithosphere
in the Alboran Sea area.
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