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. 1
Presentation Time: 1:30 PM

Near and Far Field Linkages in Permo-Carboniferous Climate, Sea-Level and Glaciation

MONTANEZ, Isabel1, BISHOP, James W.2, EROS, James M.3, GULBRANSON, Erik L.3 and CECIL, Blaine4, (1)Department of Earth and Planetary Sciences, University of California, Davis, One Shields Dr., Davis, CA 95616, (2)Chevron Energy Technology Company, 6001 Bollinger Canyon Road., D-1260, San Ramon, CA 94583, (3)Department of Geology, Univ of California, Davis, CA 95616, (4)US Geological Survey, National Center (Emeritus), Reston, VA 20192, ipmontanez@ucdavis.edu

Newly developed records from paleo-high-latitude southern Gondwana indicate a surprisingly complex glaciation history for the Late Paleozoic Ice Age (LPIA). Distribution of glaciogenic sediments in paleo-high-latitude Gondwana document intervals of widespread glaciogenic sedimentation interleaved with periods of normal marine or fluvio-deltaic sedimentation, or long-lived pedogenesis suggesting that the LPIA consisted of discrete glacial events punctuated by periods of glacial minima or possibly ice-free conditions. Independent evidence for such a dynamic climate history from ‘far-field' paleotropical and subtropical basins is limited. Here we present the results of our ongoing cyclostratigraphic, facies and paleosol analysis of biostratigraphically and/or U-Pb calibrated Permo-Carboniferous successions in basins across paleotropical Euramerica (Bird Spring and Appalachian basins, USA; Donets Basin, Ukraine) that reveal a highly variable glacioeustatic history mechanistically linked to shifts between climate extremes.

Changes in distribution of lithofacies, significant surfaces, and their stacking into meter to 10s of meter-scale cycles recorded in carbonate-dominated (Arrow Canyon, NV) to mixed carbonate-siliciclastic successions (Appalachian and Donets basins) record the onset of short-term (104-yr) relative sea-level fluctuations during the upper Visean (basal-most Chesterian) and delineate significant variation in amplitudes (<10 to >50 m) of inferred glacioeustasty through to the Early Permian. Synchronous cyclostratigraphic and sedimentologic changes document a late Moscovian-Kasimovian glacial minimum characterized by decreased effective moisture and increased seasonality, as well as two short-lived, early Pennsylvanian glacial minima. The enigmatic occurrence of glendonites in lower Moscovian (Atokan) Arrow Canyon cyclic strata, which record high-amplitude sea-level fluctuations, indicate near-freezing shallow tropical waters during peak glaciation. Proposed glacial minimum are coincident with ice-free conditions in Antarctica and Eastern Australia, widespread aridification, and significant floral and faunal turnover, whereas peak glacial periods are associated with increased humidity, dampened seasonality and present-day CO2 levels suggesting a strong link between tropical environmental change and high-latitude glaciation.