%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Gutscher, M.A.
%A Dominguez, S.
%A Westbrook, G.K.
%A Le Roy, P.
%A Rosas, F.
%A Duarte, J.C.
%A Terrinha, P.
%A Miranda, J.M.
%A Graindorge, D.
%A Gailler, A.
%A Sallares, Valenti
%A Bartolome, R.
%T The Gibraltar subduction : a decade of new geophysical data
%D 2012
%L fdi:010090931
%G ENG
%J Tectonophysics
%@ 0040-1951
%K ATLANTIQUE
%K ALBORAN MER ; CADIX GOLFE
%M ISI:000311323900002
%P 72-91
%R 10.1016/j.tecto.2012.08.038
%U https://www.documentation.ird.fr/hor/fdi:010090931
%> https://www.documentation.ird.fr/intranet/publi/2024-08/010090931.pdf
%V 574-575
%W Horizon (IRD)
%X The Gibraltar arc, spans a complex portion of the Africa-Eurasia plate boundary marked by slow oblique convergence and intermediate and deep focus seismicity. The seemingly contradictory observations of a young extensional marine basin surrounded by an arcuate fold-and-thrust belt, have led to competing geodynamic models (delamination and subduction). Geophysical data acquired in the past decade provide a test for these models and support a narrow east-dipping, subduction zone. Seismic refraction studies indicate oceanic crust below the western Gulf of Cadiz. Tomography of the upper mantle reveals a steep, east-dipping high P-wave velocity body, beneath Gibraltar. The anisotropic mantle fabric from SKS splitting shows arc-parallel 'fast directions', consistent with toroidal flow around a narrow, westward retreating subducting slab. The accompanying WSW advance of the Rif-Betic mountain belt has constructed a thick pile of deformed sediments, an accretionary wedge, characterized by west-vergent thrust anticlines. Bathymetric swath-mapping images an asymmetric embayment at the deformation front where a 2 km high basement ridge has collided. Subduction has slowed significantly since 5 Ma, but deformation of recent sediments and abundant mud volcanoes suggest ongoing activity in the accretionary wedge. Three possible origins for this deformation are discussed; gravitational spreading, overall NW-SE convergence between Africa and Iberia and finally a WSW tectonic push from slow, but ongoing roll-back subduction. In the absence of arc volcanism and shallow dipping thrust type earthquakes, evidence in favor of present-day subduction can only be indirect and remains the object of debate. Continued activity of the subduction offers a possible explanation for great (M > 8.5) earthquakes known to affect the area, like the famous 1755 Great Lisbon earthquake. Recent GPS studies show SW motion of stations in N Morocco at velocities of 3-6 mm/yr indicating the presence of an independent block, a 'Rif-Betic-Alboran' microplate, situated between Iberia and Africa.
%$ 066