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  • Dust in the Late Paleozoic Ice Age

    Background

    Between 2010 and 2012, Dr. Nicholas Heavens was a Postdoctoral Associate in the Department of Earth and Atmospheric Sciences at Cornell University. While there, he explored the climate of the Earth during a putative minimum in atmospheric carbon dioxide and maximum in glaciation around 300 million years ago (the Late Paleozoic Ice Age). He made use of techniques for dust and aerosol modeling in the Community Climate System Model (CCSM) pioneered by his supervisor at Cornell, Natalie Mahowald  and her collaborators. On the geology side, he primarily worked with Lynn Soreghan and Mike Soreghan at the University of Oklahomato put constraints on dust cycling variations between glacial and interglacial climates. The end result will be a first guess reconstruction of glacial dust cycling during the Late Paleozoic Ice Age, which should help identify new areas to search for evidence of dust deposition. Along the way, he studied the concept of Earth system modeling, evaluated a method for generating aerosol forcing in deep time climate simulations, and studied the Early Permian hydrological cycle.

    The National Science Foundation is currently supporting a team led by Lynn Soreghan (and including Dr. Heavens and Ms. Diawara) by a grant to make further geological investigations and modeling related to mid-latitude dust deposition and biological impacts of dust.

     

    Here, Dr. Heavens used boundary conditions from the current glacial-interglacial interval to estimate precipitation change in Early Permian Pangaea. Note the impact of precession under high eccentricity and tropical mountain glaciation. (Heavens et al., 2012, Climate of the Past Discussions)
    Alternating loess-paleosol couplets in the Early Permian Maroon Formation, Colorado, USA. Deposits like this provide important information about the ultimate sources of dust in the deep past.

     

    Latest Updates

    Our team continues to pursue new sites of dust deposition and better ways to simulate the dust cycle in deep time. In the last year, we have published or are soon to publish (1): a modeling study of the underlying causes of tropical precipitation variability in Pangaea; (2) an overview of our entire late Paleozoic dust cycle project as part of a Paleontological Society short course; (3) and a study claiming that Fe in late Paleozoic dust was far more bioavailable than dust typically is today. Along with collaborators at the University of Nottingham, Dr. Heavens has published a paper claiming that atmospheric dust deposition is the primary source of mineral matter in coal. This claim would resolve a longstanding mystery about coal composition as well as provide a way to reconstruct atmospheric dust deposition over the last 400 million years.

    References

    Sur, S., J.D. Owens, G.S. Soreghan, T.W. Lyons, R. Raiswell, N.G. Heavens, and N.M. Mahowald, 2015, Extreme eolian delivery of reactive iron to late Paleozoic icehouse seas, Geology, 43, 1099–1102, doi:10.1130/G37226.1.

    Marshall, C., D.J. Large, and N.G. Heavens, 2016, Coal derived rates of atmospheric dust deposition during the Permian, Gondwana Research, 31, 20–29, doi:10.1016/j.gr.2015.10.002.

    Heavens, N.G., 2015, Injecting Climate Modeling Into Deep Time Studies: Ideas for Nearly Every Project, The Sedimentary Record, 13(4), 4–10, doi:10.2110/sedred.2015.4.

    Soreghan, G.S., N.G. Heavens, L.A. Hinnov, S.M. Aciego, and C. Simpson, 2015, Reconstructing the dust cycle in deep time: The case of the Late Paleozoic Icehouse in: D. Polly, J.J. Head, and D.L Fox, eds., Earth-Life Transitions: Paleobiology in the Context of Earth System Evolution: The Paleontology Short Course October 31, 2015., Paleo. Soc. Spec. Pap., 21, 83–120.

    Heavens, N.G., N.M. Mahowald, G.S. Soreghan, M.J. Soreghan, and C.A. Shields, 2015, A model-based evaluation of tropical climate in Pangaea during the late Palaeozoic Icehouse, Palaeogeogr. Palaeoclimatol., Palaeoecol., 425, 109–127, doi:10.1016/j.palaeo.2015.02.024.

    G.S. Soreghan, D.E. Sweet, and N. Heavens , 2014, Upland Glaciation in Tropical Pangaea: Geologic Evidence, and Implications for Late Paleozoic Climate Modeling, the Journal of Geology , 122, 137-163, doi: 10.1086/675255.

    M.J. Soreghan, N. Heavens , G.S. Soreghan, P.K. Link, and M.A. Hamilton, 2014, High-resolution record of Permian atmospheric circulation changes inferred from geochemical, magnetic, and sedimentologic indicators in the Maroon Formation: Geological Society of America Bulletin , doi: 10.1130/B30840.1.

    N.G. Heavens, N.M. Mahowald, G.S. Soreghan, M.J. Soreghan, and C.A. Shields, 2012, Glacial-Interglacial Variability in Tropical Pangaean Precipitation during the Late Paleozoic Ice Age: Simulations with the Community Climate System Model, Climate of the Past Discussions, 8, 1915-1972 (open access).

    N.G. Heavens, C.A. Shields, and N.M. Mahowald, 2012, Sensitivity of a Deep Time Climate Simulation to Aerosol Prescription, Journal of Advances in Modeling Earth Systems, M11002, doi:10.1029/2012MS000166 (open access).

    N.G. Heavens, N.M. Mahowald, G.S. Soreghan, M.J. Soreghan, and C.A. Shields, A model-based evaluation of tropical climate in Pangaea during the late Palaeozoic Icehouse, Palaeogeogr. Palaeoclimatol., Palaeoecol., 425, 109–127, doi:10.1016/j.palaeo.2015.02.024 (preprint).

     

     

     

     

     

     

     

     

     

    Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.