This award supports a cooperative research project between Peter Ward, Department of Geological Sciences, University of Washington, and Roger Smith, South African Museum, Cape Town, South Africa. The project, which is entitled "Event Stratigraphy across the Permo-Triassic Boundary in the Karoo Basin," will examine the record of large vertebrate animal extinctions and changes in stable isotope composition across the 250 million year old Permian-Triassic boundary in South Africa.
New biostratigraphic, chemostratigraphic, and magnetostratigraphic results obtained from two terrestrial Permo-Triassic boundary sites (Bethulie and Lootsberg Pass) yield new insight into the tempo and severity of the mass extinction ending the Permian Period in the Karoo region of South Africa. Previous work by the Geological Survey of South Africa has demonstrated that the mass extinction among terrestrial vertebrates was catastrophic in the Karoo, with over two-thirds of all species disappearing at the top of the Permian. The duration of the extinction event can be estimated by calibrating the time necessary to accumulate 20m of fluvial sediments in the Permian Karoo basin. This probably is more than 10,000 and less than 100,000 years. A suggested cause of the Permo/Triassic mass extinction event was a short-lived heat pulse, probably produced by a flux of carbon dioxide into the atmosphere caused by oceanic overturn, combined with emissions from the Siberian Traps.
The proposed US-South African collaborative research will refine these estimates by producing a wealth of new fossil material and a suite of carbonate samples to be used for isotopic analysis. The new fossil information will allow a much more precise estimate of the rates of extinction in this region. The project is supported jointly by the Division of International Programs and the Division of Earth Sciences.
