U-Pb Geochronology of the Karoo Large Igneous Province, South Africa

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9725131 Encarnaci n Flood basalts represent voluminous (millions of cubic km) amounts of magma that were emplaced on continental crust. AU1 The combined Karoo and Ferrar (in Africa and Antarctica, respectively) flood basalt province is the oldest and largest of a series of flood basalt provinces that punctuated the breakup of the Gondwana supercontinent. Although the Ferrar and the southern part of the Karoo province appear to have been emplaced synchronously, and over a short interval (in about 1 million years) the timing and duration of the northern Karoo province is poorly constrained. Were the northern parts of the Karoo magmatic province emplaced over a brief period, and were they synchronous with the southern province? What is the timing of early alkaline magmatism in relation to the dominant tholeiitic magmatism, and the later rhyolitic events in the north? Are there any younger magmatic events that may be associated with final rupture of Africa and Antarctica and seafloor spreading? Answers to these questions bear on the magmatic evolution of this large igneous province, its relationship to mantle thermal anomalies (plumes?), lithospheric extension, and continental breakup, and may provide insight to the relationship between flood basalt events and mass extinctions. This project aims to approach these issues by obtaining precise age constraints on a variety of samples in the Karoo province. AU1