Weddell triple junction: The principal focus of Ferrar and Karoo magmatismduring initial breakup of Gondwana

Middle Jurassic Ferrar tholeiites of Antarctica were emplaced during a shor t time interval (<1 m.y.) into an active rift system initiated in the Early Jurassic. Ferrar magmas were dispersed into the Antarctic sector of Gondwa na 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 geochemi cal similarities to Ferrar rocks. Tectonic and geochemical relationships of the Ferrar and Karoo low-Ti magmas, which constitute a major part of the J urassic Gondwana large igneous province, suggest that they were derived fro m a single source associated with a triple junction in the proto-Weddell Se a region.