Karoo-Ferrar

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The Karoo and Ferrar large igneous provinces (LIPs), in Southern Africa and Antarctica respectively, collectively known as the Karoo-Ferrar, Gondwana, or Southeast African LIP, are associated with the initial break-up of the Gondwana supercontinent at c. 183 Ma. Its flood basalt mostly covers South Africa and Antarctica, but portions extend further into southern Africa and into South America, India, Australia and New Zealand. Karoo-Ferrar formed just prior to the breakup of Gondwana in the Lower Jurassic epoch, about 183 million years ago; this timing corresponds to the early Toarcian anoxic event and the Pliensbachian-Toarcian extinction. It covered about 3 million km2. The total original volume of the flow, which extends over a distance in excess of 6000 km (4000 km in Antarctica alone), was in excess of 2.5 million km3 (2.5 million cubic kilometres). The Ferrar LIP is notable for long-distance transport and the Karoo LIP for its large volume and chemical diversity. The igneous activity of the Karoo LIP began c. 204 Ma at the northern margin of the province. The long-lasting Chon-Aike Province in Patagonia, the Antarctic Peninsula, and Ellsworth Land was activated c. 190 Ma in an unstable tectonic environment in which both extension and subduction occurred. Chon-Aike had a peak between 183 to 173 Ma but produced continued magmatism between 168 to 141 Ma. By 184 to 175 Ma the Karoo magmatism had spread to Namibia, Lesotho, Lebombo, and the Ferrar province in Antarctica. The Karoo LIP ended 145 Ma with peripheral eruptions in Patagonia, the Antarctica Peninsula, northern South Africa, Kerala in India, and southeast Australia. The Karoo Province uplifted southern Africa c. 1.5 km (0.93 mi) and broke East Gondwana (India, Antarctica, and Australia) away from West Gondwana (South America and Africa) beginning in the opening of the Weddell Sea. In the Cretaceous, some...