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Mesoproterozoic activity is scarce and scattered and therefore unlikely to represent a major crust 22 generation pulse in the source area of the siliciclastic unit. The data set also records an Archean 23 orogenic pulse in its source area followed by a long lasting crust reworking process, where the 24 Eburnean juvenile materials intruded. These data are interpreted as indicative of a West Africa 25 Craton provenance, where the siliciclastic series from which the Cariño Gneisses are derived 26 were probably deposited in a back-arc type basin where detritus was mostly sourced by the 27 continent rather than the magmatic arc.

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In the Ossa Morena Domain of SW Iberia, the Calzadilla Ophiolite is formed by an ensemble of ultramafic and mafic rocks that seem to represent a fragment of an oceanic Moho transition zone. The ophiolite consists of a main sheet with a minimum thickness of c. 1000 m and several ultramafic slices that appear imbricated with Ediacaran siliciclastic rocks of the so called Serie Negra. The mafic rocks of the Calzadilla Ophiolite show an extreme depletion in some HFSE such as Nb, Zr, Th, Hf and Ta, low TiO 2 contents and high MgO, which allow identifying them as magmatic types of boninitic affinity, such as those frequently associated with fore-arc settings. U-Pb zircon dating of the gabbroic rocks suggests that the igneous protoliths crystallised at c. 600 Ma and were extracted directly from the mantle, according to the juvenile isotopic sources revealed by the Hf isotopic composition of the dated zircons. At c. 540 Ma the U-Pb isotopic system was affected by a partial resetting event with moderate generation of new zircon. According to these data, it is considered that the Calzadilla Ophiolite was formed in a suprasubduction zone setting, very likely in a fore-arc domain, during a roll-back episode affecting the peri-Gondwanan subductive slab. The fore-arc domain was probably proximal to the West Africa Craton. It is very likely that the ductile deformation, metamorphism and tectonic imbrication of the Calzadilla Ophiolite and the Serie Negra occurred at c. 540 Ma, during an increase in the subduction rate and a significant decrease of the subduction angle of the oceanic slab. The information provided by the Calzadilla Ophiolite allows to better constrain the geodynamic evolution of the African margin of Gondwana.