In the Iberian Massif, the Ossa-Morena Complex and its prolongation in the NW Iberia allochthonous complexes represent the outermost section of the North African margin of Gondwana. This margin hosted a long-lived magmatic arc active at least between c. 750 to 500 Ma. The activity of this arc can be traced by sedimentary sequences deposited along the margin and igneous rocks generated during the arc construction, as well as by deposits generated during its progressive dismantling. The dynamic evolution of the peri-Gondwanan North-African margin from the Late Ediacaran to the Early Cambrian resulted in a complex tectonic configuration involving units with continental affinity and others of oceanic/transitional nature. This PhD Thesis presents the results obtained from the study of this margin section preserved in SW Iberia and suggests a possible geodynamic and petrogenetic model based on its geochemical and isotopic evolution. This peri-Gondwanan arc section is probably one of the best well-preserved in the Variscan Orogen. The results also include the identification of previously undescribed tectonostratigraphic units, and the detailed description of a new ophiolitic unit, the MĂ©rida Ophiolite.The methodology used includes a structural study of the units implied in this section, whole-rock and isotopic (Sr-Nd) geochemistry, and geochronology (U-Pb ) of implied rocks. The study of the Merida ophiolite further included Hf isotopes in the analyzed zircons. The results have been published in journals of impact in Earth Sciences. In this sense, this volume is presented as a compilation of publications following a chronological and thematic order…