Tectonometamorphic evolution of the Aracena metamorphic belt (SW Spain) resulting from ridge‐trench interaction during Variscan plate convergence

Abstract

[1] The Aracena metamorphic belt is a hightemperature/low-pressure (HT/LP) band located at the southern end of the European Variscan chain. It marks a suture between Armorica and Avalonia. This belt is characterized by (1) the presence of mid-ocean ridge basalt-derived metabasites that were affected by an inverted HT/LP metamorphism related to SW verging thrusting, whose thermal peak diachronously migrated eastward; (2) the occurrence of a HT/LP metamorphism, related to an extensional event, affecting continental rocks belonging to the Ossa Morena zone with peak temperatures that are $150°C higher than that recorded in the oceanic metabasites; and (3) the presence of near-trench magmatism with high-Mg andesite composition. These and other characteristics can be interpreted in terms of a ridgetrench-trench triple junction that migrated along the Armorican margin during Variscan oblique convergence. Citation: Díaz Azpiroz, M., C. Fernández, A. Castro, and M. El-Biad (2006), Tectonometamorphic evolution of the Aracena metamorphic belt (SW Spain) resulting from ridgetrench interaction during Variscan plate convergence, Tectonics, 25, TC1001,

The role of strain localization in magma injection into a transtensional shear zone (Variscan belt, SW Iberia)

“…1). In SW Iberia, the Variscan structures have been related to three deformation episodes (Díaz-Azpiroz et al 2006;Ribeiro et al 2007;Rosas et al 2008). D 1 deformation has been tentatively ascribed to a phase of contraction as a consequence of subduction of the Rheic oceanic crust in the Mid-to Late Devonian (Díaz-Azpiroz et al 2006;Ribeiro et al 2007;Rosas et al 2008) but this is still controversial (Pereira et al 2009b).…”

The multistage crystallization of zircon in calc-alkaline granitoids: U–Pb age constraints on the timing of Variscan tectonic activity in SW Iberia

“…The Rheic suture has been defined consensually, in western and central Europe, separating tectonostratigraphic zones with Gondwana or Laurussia affinity (Franke 2000;Martinez-Catalan et al 2007;Murphy et al 2009). In SW Iberia, the Rheic suture separates two distinct tectonostratigraphic zones (Díaz Azpiroz et al 2006;Simancas et al 2009;Braid et al 2010;Ribeiro et al 2010;Pereira et al 2012a): (1) the Ossa-Morena-Zone and (2) the South Portuguese Zone.…”

“…The suture of the Rheic Ocean in SW Iberia, resulting from the collision of two continental blocks during the amalgamation of Pangea (Laurussia and Gondwana), is located at the boundary between the Ossa-Morena and South Portuguese zones (Eden 1991;Quesada et al 1994;Díaz Azpiroz et al 2006;Ribeiro et al 2010;Braid et al 2011;Pereira et al 2012a, b). One of the most important discussions surrounding the Variscan orogen of SW Iberia concerns the tectonic setting of Early Carboniferous Abstract CL imaging and U-Th-Pb data for a population of zircons from two of the Évora Massif granitoids (Ossa-Morena Zone, SW Iberia) show that both calcalkaline granitoids have zircon populations dominated by grains with cores and rims either showing or not showing differences in Th/U ratio, and having ages in the range ca.…”

An eastern Mediterranean analogue for the Late Palaeozoic evolution of the Pangaean suture zone in SW Iberia

“…To the north, the Beja Acebuches Ophiolite (Munhá et al 1986) occurs in the hanging-wall of the Southern Iberian Shear Zone (Crespo-Blanc & Orozco 1988, Fig. 4) between the Pulo do Lobo Zone and Ossa Morena Zone, is in faulted contact with both units, was metamorphosed up to HT/LP granulite conditions (Bard 1969;Quesada & Munhá 1990;Castro et al 1999;Díaz-Aspíroz et al 2006), and has NMORB to EMORB geochemical affinities (Munhá et al 1986;Silva et al 1990;Quesada et al 1994). Collectively these data suggest that the Beja Acebuches Ophiolite was probably emplaced in a marginal basin.…”