Early Miocene strike-slip tectonics and granite emplacement in the Alboran Domain (Rif Chain, Morocco): significance for the geodynamic evolution of Western Mediterranean Federico Rossetti a, ⁎, Andrea Dini b , Federico Lucci a , Mohamed Bouybaouenne c , Claudio Faccenna a a Dipartimento di Scienze, Università Roma Tre, 00146 Roma, Italy b CNR, Istituto di Geoscienze e Georisorse, 56124 Pisa, Italy c Département de Géologie, Universit de Rabat, BP 1014 Rabat, Morocco abstract article info Article history: Received 27 August 2012 Received in revised form 30 July 2013 Accepted 4 August 2013 Available online 14 August 2013 Keywords: Strike-slip tectonics Granite magmatism and emplacement Early Miocene Alboran Domain Mediterranean region The Neogene tectonic evolution of the western Mediterranean region is accompanied and outlasted by diffuse magmatism. This study describes the tectonic setting, the petrography and geochemistry of the Early Miocene granitic dyke swarm that occurs in the Oued Amter area, in the core of the Alboran Domain of the Moroccan Rif. The structural setting indicates dyke intrusion assisted and controlled by strike-slip tectonics that operated through conjugate, NW–SE left-lateral and NE–SW right-lateral fault strands. The overall composition of the dykes (the high SiO 2 contents (69–77 wt.%), coupled with low concentrations of TiO 2 , MgO, FeO, CaO), the high 87 Sr/ 86 Sr (0.719–0.722) and the low 143 Nd/ 144 Nd (ca. 0.5120) values point to a predominantly crustal origin of these magmatic bodies, compatible with a process involving muscovite–(biotite) dehydration melting of fertile metasedimentary sources. The isotopic signature is similar to that of the basement rocks of the Alboran Sea, suggesting for a similar crustal source for the Early Miocene felsic magmatism of the Betic–Rif realm. When framed within the regional setting, these data are used to propose a synthetic geodynamic model for the Early Miocene tectonic and magmatic evolution of the western Mediterranean region. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The arcuate orogenic belt running from the Betics (Spain) to the Rif (Morocco) across the Gibraltar Arc forms the western termination of the Mediterranean Alpine orogenic system (Fig. 1A–B). This orogen is a part of a mountain belt developed along the active margin of the western Mediterranean subduction zone during the Mesozoic–Cenozoic conver- gence between African and Iberia–Eurasia plates (e.g. Booth-Rea et al., 2007; Calvert et al., 2000; Carminati et al., 1998; Dewey et al., 1989; Faccenna et al., 2004; Hidas et al., 2013; Jolivet et al., 2008; Lonergan and White, 1997; Platt, 2007; Platt et al., 2003a; Zeck, 1996). The meta- morphic core of this orogen, known in the literature as the Alboran Do- main, is now dismembered into discontinuous outcrops located in the internal domains of the mountain fronts, where post-orogenic Oligo- cene–Miocene extensional tectonics overprinted the early Eocene crust- al thickening event (Dewey, 1988; Faccenna et al., 2004; García-Dueñas et al., 1992; Jolivet and Faccenna, 2000; Jolivet et al., 2008; Michard et al., 2006; Platt, 2007; Platt and Vissers, 1989; Platt et al., 2003b,c; 2006). The Oligocene–Miocene crustal thinning in the Alboran region was associated with a diffuse LP/HT metamorphism (e.g., Michard et al., 2006; Negro et al., 2006; Platt et al., 1998; Rossetti et al., 2005; Simancas and Campos, 1993; Soto and Platt, 1999), and with the rapid exhumation of the deep-seated orogenic roots that mainly occurred during the Early Miocene (Platt and Whitehouse, 1999; Platt et al., 1998, 2003b; Zeck et al., 1992). Remarkably, the Early Miocene high- grade tectonothermal event reworked a polymetamorphic (Alpine and pre-Alpine) basement crustal section (Michard et al., 1997, 2006; Montel et al., 2001; Platt and Whitehouse, 1999; Platt et al., 2003a,b; Rossetti et al., 2010; Zeck and Whitehouse, 2002), and still debated are the role and significance of the pre-Alpine (Variscan) history in the tectono-metamorphic evolution of the high-grade portions of the Alboran Domain (cfr. Rossetti et al., 2010). The exhumation and the intracrustal emplacement of the sublithospheric mantle bodies of the Beni Bousera and Ronda peridotite massifs exposed in the inner sectors of the Betic–Rif chain (Fig. 1B) are also commonly framed within the Ol- igocene–Miocene time frame, despite contrasting geodynamic models have been proposed so far (cfr. Platt and Vissers, 1989; Tubia et al., 1997, 2004; Lenoir et al., 2001; Cuevas et al., 2006; Garrido et al., 2011; Mazzoli and Martín Algarra, 2011; Marchesi et al., 2012; Hidas et al., 2013). In particular, Marchesi et al. (2012) documented a subduction-related geochemical fingerprint for the intrusive Cr- rich pyroxenites in the Ronda Peridotite, proposing a unitary Late Oligocene–Early Miocene supra-subduction setting for the Alboran Domain. Tectonophysics 608 (2013) 774–791 ⁎ Corresponding author at: Dipartimento di Scienze, Sezione di Scienze Geologiche, Universita Roma Tre, Largo S. L. Murialdo, 1, 00146 Roma, Italy. Fax: +39 0657338201. E-mail address: rossetti@uniroma3.it (F. Rossetti). 0040-1951/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tecto.2013.08.002 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto