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482 International Journal of Earth Sciences (2021) 110:467–485 13 (Arenas et al. 2016a; Díez Fernández et al. 2016). The Vari- scan orogenic evolution resulted in an intricate amalgama- tion of terranes with different origin and tectonothermal evo- lution, which make it difficult to correlate units along the orogen. The (North African) margin of Gondwana has been interpreted as a long-lived magmatic arc, probably active in the period ranging between c. 750 and 500 Ma (Linnemann et al. 2004; Rodriguez-Alonso et al. 2004; Pereira et al. 2006, 2012b; Andonaegui et al. 2016). The activity of this magmatic arc can be tracked by both the related igneous rocks and through the sedimentary record generated during its progressive dismantling. Associated with the (North African) margin of Gond- wana, the deposition of the Ediacaran Serie Negra Group has been traditionally considered as related to the opening of a peri-Gondwanan back-arc (Bandrés 2001). However, recent interpretations have also considered the possible deposition in a fore-arc basin opened during a short event of roll-back of the peri-Gondwanan trench that occurred at c. 600 Ma. The roll-back event favoured the generation of new oceanic lithosphere of supra-subduction zone type (Arenas et al. 2018; Díez Fernández et al. 2019). This new buoyant oce- anic lithosphere was promptly obducted onto the magmatic arc as one of the ophiolites preserved in the Ossa–Morena Complex (Calzadilla Ophiolite). The major and trace ele- ment geochemistry, as well as the Nd isotopic data provided in this contribution for the Montemolín and Tentudía forma- tions, are compatible with both (back- or fore-arc) tectonic settings affecting the thinned margin of Gondwana. The constant highly negative ε Nd ( t ) values obtained for the Montemolín and Tentudía formations, constrained to a narrow interval ranging between −6.9 and −11.5, are paired to a relatively narrow interval of Paleoproterozoic Nd model ages ranging between 1686 and 1918 Ma. The limited vari- ability of their Nd T (DM) model ages seems to indicate that they shared a common-source scenario for a long time. The detrital input derived from this source area remained essen- tially unchanged at least during the depositional time of the Montemolín and Tentudía formations, which ranges between c. 600 and 541 Ma. Altogether, these Nd model ages repli- cate the outcome obtained for the Serie Negra Group in the northern part of the Ossa–Morena Complex, in the Obejo- Valsequillo Domain (Rojo-Pérez et al. 2019). The Nd model ages obtained for the Serie Negra Group representing the Cadomian basement in the SW Iberian Massif are almost identical to those obtained for coeval sedimentary series described in the Saxo-Thuringian Zone of the Bohemian Massif (Linnemann and Romer 2002). Their very similar T DM values seem to indicate a common crustal provenance for the Ediacaran siliciclastic rocks that can be found along the Vari- scan Orogen, at least between SW Iberia and North Bohemia. A common provenance from old continental sources, previ- ously located in the Gondwana mainland, is suggested by the highly negative values and the scarce variability obtained in the εNd range shown by these series. Nd model ages ranging between 2 and 1.6 Ga can only be obtained considering Paleo- proterozoic and/or Archean sources, variably mixed with more juvenile material coming from the most external margin and/ or the magmatic arc. An Ediacaran sedimentary basin located in the Gondwanan margin in front of the West African Craton, would probably account for the isotopic features recorded in the Ediacaran siliciclastic series from SW Iberia and North Bohemia (Fig. 9). This is in agreement with previous corre- lations suggested between both regions currently separated c. 2000 km (Fernández-Suarez et al. 2002; Linnemann et al. 2008; Pereira et al. 2015). The isotopic data considered in this contribution provide evidence about the correlation and peri- Gondwanan equivalence between the Cadomian basement of SW Iberia and North Bohemia. These data also indicate that both domains were located in a similar paleo-position in the African margin of Gondwana, although they could be sepa- rated from one another by a distance that must be shorter than the current one. Superimposed Variscan tectonics would have enlarged their primary distance by moving along strike the various tectonic blocks that make the Variscan Orogen. Conse- quently, the Ediacaran siliciclastic series located in SW Iberia and North Bohemia were probably deposited in a shared (long) sedimentary basin located in the Gondwana margin in front of the West African Craton, and whose length measured along the margin is yet to be constrained. Acknowledgements Research funded by Spanish project CGL2016- 76438-P (Ministerio de Economía, Industria y Competitividad). Reviews and constructive suggestions of the manuscript performed by Manuel Francisco Pereira and a second anonymous reviewer are gratefully acknowledged, as well as the important editorial work of Axel Gerdes. Author contributions All authors have contributed actively in the crea- tion of this manuscript. Funding Research funded by Spanish project CGL2016-76438-P (Ministerio de Economía, Industria y Competitividad). Availability of data andmaterial All data utilized are included as tables and cited the sources. Code availability Not applicable. Compliance with ethical standards Conflict of interest There are no conflicts of interest. References Abalos B (1987) Tectónica y metamorfismo en el Núcleo de Almadén de la Plata (Sevilla, Zona de Ossa–Morena). PhD Thesis. Univer- sidad del País Vasco, pp 174 &KDSWHU