Structural record of Lower Miocene westward motion of the Alboran Domain in the Western Betics, Spain

Abstract

International audienceIn the framework of the Africa-Europe convergence, the Mediterranean system presents a complex interaction between subduction rollback and upper-plate deformation during the Tertiary. The western end of the system shows a narrow arcuate geometry across the Gibraltar arc, the Betic-Rif belt, in which the relationship between slab dynamics and surface tectonics is not well understood. The present study focuses on the Western Betics, which is characterized by two major thrusts: 1/ the Internal/External Zone Boundary limits the metamorphic domain (Alboran Domain) from the fold-and-thrust belts in the External Zone; 2/ the Ronda Peridotites Thrust allows the juxtaposition of a strongly attenuated lithosphere section with large bodies of sub-continental mantle rocks on top of upper crustal rocks. New structural data show that two major E-W strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60 thrusts and N140 normal faults developed simultaneously during dextral strike-slip simple shear. Olistostromic sediments of Lower Miocene age were deposited and deformed in this tectonic context and hence provide an age estimate for the inferred continuous westward translation of the Alboran Domain that is accommodated by an E-W lateral (strike-slip) ramp and a N60 frontal thrust. The crustal emplacement of large bodies of sub-continental mantle may occur at the onset of this westward thrusting in the Western Alboran domain. At lithosphere-scale, we interpret the observed deformation pattern as the subduction upper-plate expression of a lateral slab tear and its westward propagation since Lower Miocene

Extensional vs contractional Cenozoic deformation in Ibiza (Balearic Promontory, Spain): Integration in the West Mediterranean back-arc setting

“…The westward translation of the Alboran Domain, demonstrated by numerous kinematic indicators in the Betic-Rif system (e.g. Frizon de Lamotte et al, 1991;Platt et al, 2003;Plat et al, 2013;Frasca et al, 2015), is marked along the African margins by the development of pull-apart basins . Therefore, the right-lateral Formentera Basin could be a European equivalent of the left-lateral Cheliff Basin in eastern Algeria (Fig.…”

Deformation mechanisms in a continental rift up to mantle exhumation. Field evidence from the western Betics, Spain

“…3) Gibraltar arc during slab rollback (Fig.2). Consequently, the rift that lead to hyper-stretching 637 and mantle exhumation has undergone large rotations during the late stages of its 638 development and during later inversion/thrusting Frasca et al, 2015). 639…”

Fast switch from extensional exhumation to thrusting of the Ronda Peridotites (South Spain)

“…(a) Tectonic map of the Ronda Peridotites massifs (from Frasca et al., ), showing the sampling locations in the Carratraca area. A and A′ are the endpoints of the cross‐section line shown in (c).…”

“…The Ronda Peridotites Thrust (RPT, blue in Figure ; Frasca et al, ; Lundeen, ; Mazzoli and Martín‐Algarra, ; Vitale et al, ) marks the second tectonic contact of the peridotites. The rocks below the Ronda Peridotites are highly diverse, with variable degrees of metamorphism from low‐grade limestones to strongly mylonitized marbles (see summary in Frasca et al.…”

“…The rocks below the Ronda Peridotites are highly diverse, with variable degrees of metamorphism from low‐grade limestones to strongly mylonitized marbles (see summary in Frasca et al. ()). Migmatites in the footwall and granitic dikes intruding the mantle and the crustal hangingwall yield a cluster of crystallization ages between 23 and 19 Ma (Esteban et al, ; Monié et al, ; Rossetti et al., ; Sánchez‐Rodríguez & Gebauer, ; Sosson et al., ).…”