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the Serie Negra Group are compatible with an arc-related (back-arc or fore-arc) setting built on a thinned old crust. This metasedimen- tary series shares almost identical isotopic (Nd) features with other Neoproterozoic series described in the Variscan Belt, such as those from the Bohemian Massif (e.g. Linnemann et al., 2000; Linnemann and Romer, 2002), suggesting common crustal provenance and a similar paleo-position along the northern Gondwanan margin (Pereira, 2015; Rojo-Pérez et al., 2021). However, recognition of the primary configuration is difficult due to the complex deforma- tion of many of these analogous series associated with Cadomian and Variscan tectonics. The Montemolín Formation is formed in its lower (and oldest) part by metabasite lenses of variable thickness alternating with metasedimentary lithologies which have been interpreted as formed during the opening of a marginal basin in the periphery of Gondwana (continental arc setting) on the basis of their petro- graphic, metamorphic, and geochemical features (Ordóñez- Casado, 1998; Sánchez Carretero et al., 1989; Eguíluz et al., 1990; Bandrés, 2001; Sánchez-Lorda et al., 2013, 2016). However, recent works not only favour their supra-subduction geochemical affinity but also identify mechanical contacts between these and the rest of the Serie Negra Group, showing different metamorphic evolution compared to the rest of the successions surround them (Arenas et al., 2018; Díez Fernández et al., 2019). Although a precise age for the base of the Serie Negra Group is unknown, the hosted metabasic rocks would constitute the oldest magmatic episode of arc building preserved, dated ranging between c.645–585 Ma (SHRIMP U–Pb, Sánchez-Lorda et al., 2016), which is in range with the age to the mafic-ultramafic sequences and migmatitic events dated at c.600 Ma (Schäfer et al., 1993; Ordóñez-Casado, 1998; Arenas et al., 2018). Neoproterozoic magmatism is not only mafic, but also felsic. The generation of calc-alkaline melts resulted in granitic bodies, especially preserved to the north of the OMC, which appear intruding the metasedimentary Serie Negra Group. The age of these metagranitoid bodies ranging from Late Protero- zoic to Ordovician and their geochemical features varies widely in short distances (Gonzalo, 1987; Ordóñez-Casado, 1998; Bandrés, 2001; Sánchez-García et al., 2013; Bandrés et al., 2004; Galindo and Casquet 2004; Henriques et al., 2015). The northern OMC includes the Mérida Massif (Fig. 1b and Fig. 2), whose basement is formed by metasedimentary rocks anal- ogous to those described for the Serie Negra Group in the central and southern domains of the OMC, suggesting a Precambrian to Early Paleozoic age (Bandrés, 2001). The tectonostratigraphy of the Mérida Massif includes four tectonostratigraphic units (Díez Fernández et al., 2021). The lowermost unit, Magdalena Gneisses (Fig. 2), has continental crust affinity and crops out in the core of an antiform north of Mérida Massif (Fig. 2). The Cadomian myloni- tic Magdalena thrust marks the contact between the lower and intermediate unit, referred to as the Mérida Ophiolite (Fig. 2; Díez Fernández et al., 2021). The Mérida Ophiolite is constituted by metagabbros-diorites with mafic cumulates, garnet-bearing amphibolites, hornblendites, ultramafic rocks, serpentinites and some silicic dikes. The protoliths of some of these rocks have been Fig. 1. (a) Zonation of the Variscan Orogen (Díez Fernández and Arenas, 2015; Arenas et al., 2016), based on Franke (1989), Lefort (1989), Neuman and Max (1989) and Martínez Catalán (2011). Location of the geological map presented in Fig. 1b is shown by the dashed polygon. (b) Geological map of the Ossa–Morena Complex and the southern part of the Central Iberian Zone, based on the 1:1.000.000 geological map of Spain and Portugal (Rodríguez Fernández et al., 2014; Rojo-Pérez et al., 2019). Location of the geological map presented in Fig. 2 is shown by the dashed polygon. (c) Schematic stratigraphic column of the Serie Negra Group. E. Rojo-Pérez, U. Linnemann, M. Hofmann et al. Gondwana Research 109 (2022) 89–112 The Ediacaran arc section