T266 Paleozoic Oceanographic and Climatic Changes: Evidence from Seawater Geochemistry and Sedimentology Records II

Tuesday, 7 October 2008
1:30 PM - 5:30 PM

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

Paper number: T266-1
Program: Technical Sessions
Time: 1:30 PM – 1:50 PM

Authors

Abstract

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.