See more from this Division: Topical Sessions
See more from this Session: Paleozoic Oceanographic and Climatic Changes: Evidence from Seawater Geochemistry and Sedimentology Records I
Abstract:
Given that these two basins formed on separate continents occupying different paleolatitudes and suffering different tectonic stress fields, their similarity is truly astonishing and suggests extrabasinal controls (i.e., eustasy and climate) left a much more significant signature on the rock record than intrabasinal controls (i.e., tectonism). The presence of closely spaced, regularly repeating facies successions suggests relatively short duration sea level fluctuations associated with Milankovitch forcing. The change in the degree of stratigraphic facies change, and thereby amplitude of sea level fluctuation on the order of several tens of meters, suggests glacioeustacy. The immense sizes of some microbialite bioherms supports this interpreted magnitude of sea level fluctuation and are themselves considered a biologic response to increasing accommodation and unusual seawater chemistry. The change in authigenic mineralization is interpreted to represent a shift in redox conditions from primarily oxidizing to reducing, indicating a draw down in oceanic oxygen levels, perhaps resulting in increased carbon burial and ensuing carbon dioxide depletion of the atmosphere. Taken together these interpretations suggest a paradox for the Ireviken Excursion as a period of co-occurring ocean stratification and glaciation.
See more from this Division: Topical Sessions
See more from this Session: Paleozoic Oceanographic and Climatic Changes: Evidence from Seawater Geochemistry and Sedimentology Records I