Volcanic rifted margins are a major type of large igneous provinces, characterized by seaward dipping reflector sequences, normally associated with subaerially emplaced basalt flows and intercalated continental sediments. The lateral extent of the volcanics can reach a few hundred kilometers with a thickness of about 10 kilometers. A number of questions remain concerning their formation. These include the influence of hotspots, the timing of volcanic emplacement with respect to continental breakup, the nature of the crust associated with the volcanics, and the symmetry of the volcanics with respect to the breakup axis. We investigate the geologic evolution of conjugate margins in the South Atlantic during the early Cretaceous, through the study of the Pelotas Basin (offshore South Brazil) and the northern portion of the Namibian margin (Southwest Africa). We analyzed 1500 km of seismic lines and four industry wells from Petrobras in Pelotas Basin, and almost 3,000 Km of seismic lines from the Namibe and Walvis basins (Northern Namibia continental margin) together with DSDP sites 362, 530, 531, and 532. Current models to explain the formation of the volcanics range from emplacement during rifting to accretion of a thickened oceanic crust during initial seafloor spreading. We discuss the above analysis in light of the current models to infer the mechanism of emplacement.