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Examining the Complexity of Environmental Change during the Late Paleozoic and Early Mesozoic

¹ Department of Geosciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, USA jisbell@uwm.edu

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The late Paleozoic and early Mesozoic was a time of tremendous upheaval on Earth with severe climatic change and biotic crises. These events, which represent Earth systems' response to changing environmental drivers, are the focus of our research. Although climate and biotic changes are often considered as separate entities, we consider them to be part of an environmental continuum of results ensuing from common driving mechanisms (i.e., Fischer, 1982; Berner, 2004).

Glaciation during the late Paleozoic is arguably one of the most important climatic events of the Phanerozoic, as it is hypothesized that this event dramatically influenced Earth's biological, physical, and chemical systems (Gastaldo et al., 1996; Montañez et al., 2007). Studies of Upper Devonian, Carboniferous, and Permian strata provide a deep-time perspective on the potential outcomes (conditions and driving mechanisms) of current climatic perturbations (IPCC, 2007), as these strata record the only complete greenhouse to icehouse to greenhouse cycle on a vegetated Earth, and because the glaciation was bipolar. Despite the importance of the late Paleozoic Ice Age (LPIA), many aspects of this period are unknown. Basic questions that remain include: (1) What was the size and duration of individual glacial events? (2) How did the glaciation influence oceanic and atmospheric circulation? (3) What were the glacioeustatic effects of the glaciation? (4) What geochemical signals accurately reflect the size and duration of the glaciation? (5) What driving mechanisms controlled the development and demise of the LPIA?

The LPIA has long been considered a 90+ myr event characterized by an extensive ice sheet that covered much of Gondwana (e.g., Veevers and Powell, 1987; Frakes and Francis, 1988). The origin and perpetuation of this concept is founded primarily from far-field studies of low paleolatitude European and American coal-bearing cyclothems. These strata have . . . [Full Text of this Article]