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juxtaposition, as rift-related magmatism that occurs near the boundary between the Central Iberian Zone and the Ossa-Morena Complex (Díez Fernández et al., 2015) actually implies separation of terranes. Latest Ediacaran convergence has been recently found as responsible for the juxtaposition of Ediacaran series within the Ossa-Morena Complex (Díez Fernández et al., 2019). However, lateral components of con- vergence inferred for that period are sinistral, what would move away the terranes under discussion. Finally, Variscan deformation in the Iberian Massif has been largely acknowledged as the result of the pro- gressive dextral collision between Laurussia, Gondwana and their peri- continental terranes (e.g., Martínez Catalán, 1990, 2011). Such oro- genic scenario includes the lateral dextral components required for the juxtaposition of the studied series, but so far, no major strike-slip shear zone has been observed along the boundary between the Central Iberian Zone and the Ossa-Morena Complex that could have taken the right-lateral displacements required. The current boundary between the northern Ossa-Morena Complex and the southern Central Iberian Zone is a dip-slip Variscan extensional fault (Martín Parra et al., 2006). A normal fault like this cannot explain the juxtaposition of formerly distant terranes that were located laterally along the margin of Gondwana. This is because that fault actually moves away the two terranes and includes negligible, if any, along- strike movement. Díez Fernández and Arenas (2015) recognized the primary Variscan contact between the Ossa-Morena Complex and the Central Iberian Zone as a major thrust equivalent to the one that em- placed the Allochthonous Complexes of NW Iberia onto the Central Iberian Zone (Fig. 2). In a dextral convergence setting such as the Variscan orogeny, a major thrust like this one can achieve the juxta- position of distant terranes as required for the study case. In fact, the large tectonic transport inferred for this primary thrust, if measured across the margin of Gondwana (several hundred kilometers; Díez Fernández et al., 2016), makes it more likely that the two Ediacaran series here compared did not belong to two laterally distant sections of the same basin, but to two sections of two different basins within a broad Ediacaran peri-Gondwanan arc-system. Similar offsets in the pre-Variscan paleogeographic position of peri- Gondwanan terranes that are now juxtaposed by Variscan faults can also be observed in other sections of the orogen. The first one that was documented by provenance analysis of metasedimentary sequences was that of the Devonian suture zone exposed in NW Iberia. There, al- lochthonous terranes derived from westernmost positions along the margin of Gondwana (Fernández-Suárez et al., 2003), are currently juxtaposed onto others that were located more to the East (Díez Fernández et al., 2010). This offset in the paleogeography mimics what is observed along the boundary between the Obejo-Valsequillo Domain and the Central Iberian Zone, thus reinforcing the idea that the latter represents another occurrence of the suture zone observed in NW Iberia. This way, geochemical and provenance (e.g., Sm-Nd) analysis of sedimentary sequences emerges as a reference tool for recognizing major tectonic boundaries within orogenic systems, the paleogeo- graphic offsets inferred for currently juxtaposed Ediacaran series being a promising target to use it. So far, the results obtained for the Iberian Massif are solid, thus a similar approach could be likely implemented in other areas with similar geology along the Variscan Orogen to test the existence of major tectonic boundaries in the absence of clear structural and petrological indicators. 6. Conclusions In the Iberian Massif, the Sm-Nd isotopic composition of coeval Ediacaran siliciclastic rocks, located at each side of the Central Iberian Zone – Ossa Morena Complex boundary, is very different. To the south of that boundary (Ossa Morena Complex), the Serie Negra shows older TDM values ranging 1421–2040 Ma, and was probably deposited in the frontal part of a volcanic arc built on an extended section of the margin of the West Africa Craton. Immediately to the north (Central Iberian Zone), the Lower Alcudian Series has younger TDM values, in the range of 1256–1334 Ma, and was likely deposited in a peri-Gondwanan back- arc basin located more to the east of the West African Craton. The differences in Sm-Nd isotopic composition indicate contrasted source areas, and do not support the deposition of both series close to one another, as opposed to how they are observed today. The Sm-Nd data suggest a different location along the margin of Gondwana for the de- position of each series during Ediacaran times. A more eastern paleo- geographic position is inferred for the Central Iberian Zone relative to the Ossa-Morena Complex, as also supported by provenance analysis based on U-Pb geochronology of detrital zircons. The boundary be- tween the Central Iberian Zone and the Obejo-Valsequillo Domain (Ossa-Morena Complex) is not transitional, as the current juxtaposition of Ediacaran series at each side requires significant tectonic transport. Although some contribution of Ediacaran (Cadomian) and Early Paleozoic structures cannot be ruled out, Variscan thrusting developed in a dextral convergence setting is found as the main contributor to the current juxtaposition of Ediacaran series along this boundary. This conclusion can be very likely extrapolated to some other equivalent boundaries throughout the Variscan Orogen. Acknowledgements Constructive reviews of the manuscript by Jean-Paul Liégeois and Jürgen von Raumer are kindly acknowledged. 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