ABR/RUI Is the Terrestrial Permian-Triassic Boundary in the Karoo Basin? Implications for the Response of the Terrestrial Ecosystems to the End-Permian Extinction Event

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Earth's biosphere experienced its greatest mass extinction ~251.9 million years ago at the end of the Permian Age. In approximately 60,000 years, the oceans experienced a loss of 90% of marine life. Many workers believe that a similar change co-occurred on land, but rock-and-fossil records from the continents are not well dated. For more than a century, the Karoo Basin, South Africa, has served as the center for interpreting the response of terrestrial ecosystems to this crisis. The current proposal uses a multidisciplinary, international team of geoscientists to refine the physical and chemical conditions around which the biological event is believed to have occurred in this basin. Field-and-laboratory training of undergraduate STEM students continues to be an integral component of the project, educating the next generation of geoscientists in an understanding of Earth Systems in deep time. Mechanisms responsible for the end-Permian biodiversity loss are attributed to changes in atmospheric and oceanic chemistries. These were a consequence of the emplacement of basalt in a large igneous province, the Siberian Traps. Increasing atmospheric gas concentrations, accompanied by increasing global temperatures, stressed the physiological limits of the plants and animals. It is essential to know if these stresses affected both marine and terrestrial ecosystems, concurrently, or if their responses are temporally out of phase. This project will use stratigraphy, sedimentology, magnetic rock properties, and whole-rock and stable-isotope geochemistry to look at the physical and chemical conditions, in addition to paleontology and palynology to determine the biological components, and constrain these in time (employing high resolution geochronology). An empirical model will be developed to assess the stratigraphic applicability of paleobiological data, leading to a better interpretation of the latest Permian to earliest Triassic terrestrial transition.