RT Journal Article
T1 Arc-parallel vs back-arc extension in the Western Gibraltar arc:  Is the Gibraltar forearc still active?
A1 Balanyá Roure, Juan Carlos
A1 Crespo-Blanc, Ana
A1 Díaz Azpiroz, Manuel
A1 Expósito Ramos, Inmaculada
A1 Torcal Medina, Federico
A1 Pérez-Peña, José Vicente
A1 Booth-Rea, Guillermo
K1 Forearc tectonics
K1 Strain partitioning
K1 Crustal earthquakes
K1 Gibraltar arc
AB A B S T R A C T Extremely tight arcs, framed within the Eurasia-Africa convergence region, developed during the Neogene on both sides of the western Mediterranean. A complex interplate deformation zone has been invoked to explain their structural trend-line patterns, the shortening directions and the development of back-arc basins. Updated structural and kinematic maps, combined with earthquake data covering the complete hinge zone of the western Gibraltar arc help us to explore the mode of strain partitioning from 25My ago to present. During the Miocene, the strain partitioning pattern showed arc-perpendicular shortening in the active orogenic wedge –assessed from the ra dial pattern of tectonic transport directions– accompained by subhorizontal stretching. Structures accommodating stretching fall into two categories on the basis of their space distribution and their relationships with the structural trend-line pattern: i) arc-parallel stretching structures in the external wedge (mainly normal faults and conjugate strike-slip faults); and ii) extensional faults developed in the hinterland zone in which transport directions are centripetal towards the Alborán back-arc basin. Pliocene to Recent deformational structures together with focal solutions from crustal earthquakes (n=167; 1.5<Mw<6.3) support that this strain partitioning pattern still occurs. By contrast, the eastern end zones of the western Gibraltar arc, especially during the last 5My, underwent intense transpression tectonics with a NW to NNW main shortening axis. These results agree with a still active Gibraltar forearc, governed by westward migrating subduction retreat or subcontinental mantle delamination.
PB Servei de Publicacions, Universitat Autònoma de Barcelona
YR 2012
FD 2012-09
LK https://hdl.handle.net/10433/26370
UL https://hdl.handle.net/10433/26370
LA en
NO G e o l o g i c a A c t a , V o l . 1 0 , N º 3 , S e p t e m b e r 2 0 1 2 , 2 4 9 - 2 6 3 D O I : 1 0 . 1 3 4 4 / 1 0 5 . 0 0 0 0 0 1 7 7 1
NO Proyectos de investigaciónThis study was supported by Spanish research projects of the Ministerio de Ciencia e Innovación (CGL2008-03249, CGL2009- 11384 and CONSOLIDER-INGENIO2010-CSD2006-00041), and of the Junta de Andalucía (RNM 215 and RNM3713).
NO Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturales
NO Departamento de Geodinámica, Universidad de Granada
NO Instituto Andaluz de Ciencias de La Tierra
NO Instituto Andaluz de Geofísica y Prevención de Desastres SísmicosInstituto Andaluz de Geofísica y Prevención de Desastres Sísmicos
DS RIO
RD May 22, 2026