Origin of the Betic‐Rif mountain belt

Abstract

Abstract. In recent years, the origin of the BeticRif orocline has been the subject of considerable debate. Mudi of this debate has, focused on mechanisms required to generate rapid late-orogenic extension with coeval shortening. Here we summarize the principal geological and geophysical observations and propose a model for the Miocene evolution of the Betic-lq. if mountain belts, which is compatible with the evolution of the rest of the western Mediterranean. We regard palaeomagnetic data, which indicate that there have been large rotations about vertical axes, and earthquake data, which show that deep seismicity occurs beneath the Alboran Sea, to be the most significant data sets. Neither data set is satisfactorily accounted for by models which invoke convective removal or delamination of lithospheric mantle. Existing geological and geophysical observations are, however, entirely consistent with the existence of a subduction zone which rolled or peeled back until it collided with North Africa. We suggest that this ancient subducting slab consequently split into two fragments, one of which has continued to roll back, generating the Tyrrhenian Sea and forming the presentday Calabnan Arc The other slab fragment rolled back to the west, generating the Alboran Sea and the BeticRif oroctine during the early to middle Miocene.

Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs

“…2 20-15 Separation of Corsica from Sardinia (Alvarez et al, 1974;Orsini et al, 1980). 3 16-14 Opening of the Betic sea strait separated the south Iberian Betic region from the continent (Bustillo and Lopes Garcıa, 1997;Lonergan and White, 1997). 4 ca.…”

“…10 Final structuring of the Neo-Pyrenees (Oosterbroek and Arntzen, 1992). 9 10-7 Secondary contact between the Betic region and the continent occurred due to crustal shortening in the prebetic zone (eastern part of the Betic sea strait) (Lonergan and White, 1997;Weijermars, 1988). 10 8.6-7.6 The Calabro-Peloritan massif (presently Sicily and south Italy) broke off from Sardinia and started to drift eastwards (Duermeijer et al, 1998).…”

“…In this context it has to be noted that secondary contact between the Betic region and the continent is likely to have occurred ca. 10-7 MYA due to crustal narrowing in the eastern Betic sea strait (Lonergan and White, 1997;Weijermars, 1988). Based on the previous explanation, we have to assume an Iberian range of the D. galganoi/D.…”

Scenarios for earthquake-generated tsunamis on a complex tectonic area of diffuse deformation and low velocity: The Alboran Sea, Western Mediterranean

“…That which seems to be clear is the huge displacement of this crustal domain from an eastward position towards its actual location during the Neogene. Different processes have been proposed to explain this evolution and the thinning of the crust: westward displacement due to the opening of the Algero-Provenc;al Basin (Sanz de Galdeano, 1990); subduction of Africa under Iberia, being the Alboran Basin a back-arc basin (Morley, 1993); subduction of Iberia under the Betic Cordillera and the Alboran Basin (Morales et al, 1999); east dipping subduction of the Atlantic, Iberia and Africa under the Alboran domain (Royden, 1993;lonergan and White, 1997); and thinning of the crust due to convection processes in the mantle (Weijermars, 1985;Doblas and Oyarzun. 1989;Platt and Vissers, 1989;Vissers et al, 1995).…”

Geodetic constraints on active tectonics of the Western Mediterranean: Implications for the kinematics and dynamics of the Nubia-Eurasia plate boundary zone

“…Current tectonic models for the Alboran domain include four broad categories of hypotheses: (1) backarc extension driven by the A c c e p t e d M a n u s c r i p t 5 westward rollback of an eastward subducting slab of oceanic lithosphere (Royden, 1993;Lonergan and White, 1997;Gutscher et al, 2002); (2) break-off of a subducting lithospheric slab (Blanco and Spakman, 1993); (3) crustal extrusion due to forces 95 transmitted across the Eurasia-Africa plate boundary (Rebai et al, 1992;Morel and Meghraoui, 1996); and (4) delamination and convective removal of the lithospheric mantle root beneath the collisional orogen (Platt and Vissers, 1989;Seber et al, 1996;Calvert et al, 2000a;Calvert et al, 2000b). Testing these hypotheses with the present-day deformation field is a principal objective of this study.…”