2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 7
Presentation Time: 9:45 AM

Tracing the Biotic Response to Tropical Climate Change in An Evolving Ice House: A Pennsylvanian DETELO

RAYMOND, Anne, Dept. of Geology & Geophysics, Texas A&M University, College Station, TX 77843-3115, SIMS, Hallie, Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242, LAMBERT, Lance L., Dept. of Geological Sciences, Univ of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 and MARCANTONIO, Franco, High Alpine and Arctic Research Program, Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843-3115, raymond@geo.tamu.edu

The most valuable DETELOs will include a range of environments and taxonomic groups, a detailed and accurate age framework, and relevance for understanding modern climate change. Paleotropical strata from the Pennsylvanian of North America and correlative sediments in Europe and China meet these criteria. They contain copious and well-studied marine faunas, and a rich record of land plants from siliciclastic and peat-accumulating wetlands. We can trace the ecological impact of terrestrial arthropods on Pennsylvanian plant communities using coprolites and leaf damage. Coprolite size and location indicates the relative importance and diversity of detritivore functional feeding groups in these communities. Likewise, characteristic patterns of fungal attack on plants indicate the importance of major fungal groups within Pennsylvanian wetlands.

Pennsylvanian sediments accumulated during an ice-house interval and reflect Milankovitch band glacial advance and retreat. Treated as high-frequency sequences delineated by a detailed microfossil database (conodonts, fusulinids, palynomorphs), marine and terrestrial records can be linked for detailed analyses of the biotic response to fluctuating sea-levels and changes in tropical climate. Many Pennsylvanian marine shales have authigenic apatite nodules, potentially amenable to radiometric age dating using the uranium-lead isotope system. There are few, if any, absolute ages on these North American sediments, and new age constraints will aid in the development of accurate global correlations. Pennsylvanian ice sheet volume changed over time; during some intervals it may have disappeared. Size changes in the ice sheet probably drove changes in paleotropical rainfall, from relatively dry (mid-Moscovian) to wet (late Moscovian) back to relatively dry (Kasimovian). This DETELO will explore the response of tropical Pennsylvanian biotas to climate change driven by changes in polar ice volume. How did fluctuations in tropical rainfall affect terrestrial decomposition, organic carbon accumulation, nutrient supply to marine shelves and organic carbon burial in marine environments? How did Pennsylvanian marine fauna respond?