Nova Terra 52

122 &KDSWHU presence of any ophiolitic units generated either in fore- arc or back-arc domains or in the peri-Gondwanan ocean itself. Ophiolite recognition in the field is always challen- ging and must be supplemented with additional quan- titative data derived from geochronology, geochemistry, and tectonothermal modelling. In the Variscan Orogen (Figure 1a), the SW Iberian Massif contains a section of the northwest Ediacaran African margin of Gondwana, which forms part of the Upper Allochthonous Terrane of the Ossa-Morena Complex (Figure 1b; Díez Fernández and Arenas 2015; Rojo-Pérez et al . 2021). This section of the Gondwana margin is in direct contact with units belonging to the southern margin of Laurussia, represented by the South- Portuguese Zone, an Avalonian foreland (Figure 1b; Díez Fernández et al . 2016). Although deformed in Variscan times with complex structure, the Ediacaran section is generally complete and contains the transition from the outermost margin to the volcanic arc, which continues into a broad back-arc basin, represented by an Autochthonous Domain (Figure 1b). This back-arc formed along the periphery of the West African Craton (WAC; Fuenlabrada et al . 2020). Traditionally, however, research carried out in the Ediacaran section has not addressed the possible existence of units with different origins and tectonothermal evolution. The distinction of the different terranes involved has only been recognized in very recent times, which has prevented detailed reconstruction of the architecture of the peri- Gondwanan margin and the resolution of its tecto- nothermal evolution. At least two different ophiolitic units have been recently described in SW Iberia using a structural and tectonometamorphic approach. One of these, the Calzadilla Ophiolite, is located in an outermost position on the margin (Figure 1b) and its origin has been linked to the opening of a fore-arc basin (Arenas et al . 2018; Díez Fernández et al . 2019). The second ophiolite, the Mérida Ophiolite, lies in a more internal position (Figure 2) and has been interpreted as a back- arc ophiolite based on its structural position and Figure 1. a) Domains of the Variscan Orogen. b) Zonation of the Iberian Massif and location of the studied region (Figure 2). Abbreviations: AF, Azuaga Fault; BAO, Beja-Acebuches Ophiolite; CA, Carvalhal Amphibolites; CF, Canaleja Fault; CMU, Cubito-Moura Unit; CO, Calzadilla Ophiolite; BCU, Badajoz-Córdoba Unit; ET, Espina Thrust; HF, Hornachos Fault; IOMZO, Internal Ossa-Morena Complex Ophiolites; LLF, Llanos Fault; MLF, Malpica-Lamego Fault; OF, Onza Fault; OVD, Obejo-Valsequillo Domain; PG-CVD, Puente Génave-Castelo de Vide Detachment; PRF, Palas de Rei Fault; PTF, Porto-Tomar Fault; RF, Riás Fault; VF, Viveiro Fault. After Díez Fernández and Arenas (2015) and Arenas et al . (2016a) 2 R. ARENAS ET AL.