Middle Jurassic Ferrar tholeiites of Antarctica were emplaced during a short time interval (<1 m.y.) into an active rift system initiated in the Early Jurassic. Ferrar magmas were dispersed into the Antarctic sector of Gondwana from a source in the Weddell Sea region, within the thermal anomaly that also gave rise to the Karoo basaltic rocks of southern Africa. The Golden Gate lavas, part of the Karoo central area low-Ti tholeiites, show geochemical similarities to Ferrar rocks. Tectonic and geochemical relationships of the Ferrar and Karoo low-Ti magmas, which constitute a major part of the Jurassic Gondwana large igneous province, suggest that they were derived from a single source associated with a triple junction in the proto-Weddell Sea region.