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Geology
Article: pp. 745–748 | Full Text | PDF (701K)
Karoo large igneous province: Brevity, origin, and relation to mass extinction questioned by new 40Ar/39Ar age data
1. Unités Mixtes de Recherch-Centre National de la Recherche Scientifique (UMR-CNRS) 6526 Géosciences Azur, Université de Nice-Sophia Antipolis, O6108 Nice, France, 2. Unités Mixtes de Recherch-Centre National de la Recherche Scientifique (UMR-CNRS) 5570, Ecole Normale Supérieure de Lyon et Université Claude Bernard, 69364 Lyon, France, 3. Department of Geology, University of Botswana, Gaborone, Botswana, 4. School of Geological and Computer Sciences, University of Kwazulu-Natal, Durban, South Africa, 5. Unités Mixtes de Recherch-Centre National de la Recherche Scientifique (UMR-CNRS) 6538, Institut Universitaire Européen de la Mer, 29280, Plouzané, France
The peak activities of continental flood basalts are currently considered as huge and brief (∼1 m.y.) magmatic events, with strong implications for geodynamics and biotic turnover. New 40Ar/39Ar dates on the Karoo flood basalts (southern Africa) show a longer duration of magmatism (∼8 m.y., with 6 m.y. for the main volume) with an apparent south-to-north migration, along with briefer distinctive pulses inside the province. This suggests that the Karoo province does not fit the general plume model invoked for most continental flood basalts (including the Karoo) and may explain the absence of a major contemporaneous mass extinction.
Keywords: Ar/Ar dating, flood basalts, magmatism migration, mantle plume, mass extinction
Received: 25 February 2005; Revised: 18 May 2005; Accepted: 20 May 2005
DOI: 10.1130/G21632.1
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