Early Triassic productivity crises delayed recovery from world’s worst mass extinction

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  • Stephen E. Grasby
    1Geological Survey of Canada, Natural Resources Canada, Calgary, Alberta T2L 2A7, Canada
  • Benoit Beauchamp
    2Department of Geoscience, University of Calgary, Alberta T2N 1N4, Canada
  • Jochen Knies
    3Geological Survey of Norway, 7491 Trondheim, Norway

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<jats:title>Abstract</jats:title> <jats:p>The recovery of life after the latest Permian extinction was protracted over Early Triassic time. Detailed geochemistry of marine sections along northwest Pangea indicates that upwelling ceased at the extinction event. Nitrogen stable isotope data suggest that this was associated with progressive increase in nutrient stress throughout the Early Triassic, coincident with a significant decrease in organic carbon content despite pervasive anoxic to euxinic conditions. We argue that the Early Triassic hothouse both reduced marine productivity and deepened the nutricline, reducing the overall rate of nutrient delivery to the photic zone, creating an Early Triassic nutrient gap. When oceans finally cooled by Middle Triassic time, renewed nutrient upwelling and onset of organic-rich shale deposition occurred across northwest Pangea, marking the final return of global marine productivity.</jats:p>

Journal

  • Geology

    Geology 44 (9), 779-782, 2016-09-01

    Geological Society of America

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