Paper No. 11
Presentation Time: 10:50 AM

GRADIENTS IN NUTRIENT DISTRIBUTION AND PRODUCTIVITY IN NORTHEAST PANTHALASSA ACROSS THE PTB


SCHOEPFER, Shane D., Earth and Space Sciences, University of Washington, Seattle, WA 98105, ALGEO, Thomas J., Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, HENDERSON, Charles, Geology and Geophysics, Univ of Calgary, Calgary, AB T2N 1N4, Canada and WARD, Peter D., Departments of Biology and Earth and Space Sciences, University of Washington, Kincaid Hall, Seattle, WA 98125, shanedms@uw.edu

This study compiles nitrogen isotope and productivity proxy data from six widely separated sections in the broadly-defined northeastern Panthalassic Ocean spanning the Permian-Triassic boundary. Evidence of coastal upwelling along western Pangaea can be observed in the subtropical Opal Creek section as well as the more northerly Peck Creek, with a latitudinal gradient in intensity. This modality of circulation substantially weakened at the Permian-Triassic boundary, likely in response to warming, leading to a transition from predominantly eutrophic to oligotrophic environments, however a latitudinal gradient in nutrient availability was preserved. An onshore to offshore gradient in productivity is observed between Peck Creek and the more basinal Ursula Creek section in northern British Columbia, at the northern margin of the upwelling system. Comparison of the behavior of trace-element productivity proxies suggest upwelling fueled sulfate reduction primarily at lower latitudes. Severe nitrogen limitation is observed in abyssal Panthalassic sections, but further investigation is needed to separate the effects of depositional location in a nutrient-starved environment from the effects of denitrification in an anoxic water mass. Further work will incorporate Tethyan and peri-Tethyan sections and place these results in a global context.