Physical Sciences and Mathematics Commons^™

Sedimentological And Geochemical Analysis Of Deep-Water Deposits In The Mojón De Hierro Formation At Arroyo Garrido, Tepuel-Genoa Basin, Patagonia, Argentina, Natalie Beatrice Mcnall

Theses and Dissertations

The Earth has had multiple Phanerozoic glacial intervals but the Late Paleozoic Ice Age (LPIA) was its longest and most extensive, lasting from the Late Devonian (~372 Ma) until the Late Permian (~254 Ma). The LPIA is the last complete climate shift from a greenhouse to icehouse and back to a greenhouse state and the only one to occur on a biologically complex Earth. Therefore, it provides perspectives on deep-time climatic transitions, the parameters controlling them, and the Earth’s physical, chemical and biological responses to such climate changes. Research on mid to high-latitude deposits in Gondwana provides evidence that the …

Early Mississippian Ocean Anoxia Triggering Organic Carbon Burial And Enhancing Late Paleozoic Ice Age Onset: Evidence From Uranium Isotopes Of Marine Limestones, Keyi Cheng

Earth and Planetary Sciences ETDs

The Early Mississippian (Tournaisian) positive δ¹³C excursion (or TICE) is one of the largest recorded in the Phanerozoic and the organic carbon (OC) burial associated with its development is hypothesized to have driven global cooling and increased glaciation. We are testing the hypothesis that expanded ocean euxinia/anoxia drove widespread OC burial and the TICE and we are testing this hypothesis using uranium isotopes (δ²³⁸U) of Lower Mississippian marine limestones from southern Nevada as a global seawater redox proxy.

δ²³⁸U trends record a prominent mid-Tournaisian negative excursion (~0.30‰ magnitude) lasting ~1 My. The lack of …

Testing The Late Paleozoic Ice Volume Paradox In The Southernmost Paraná Basin, Brazil, Nicholas David Fedorchuk

Theses and Dissertations

The late Paleozoic ice age (LPIA; ~372-259 Ma) was the last complete transition from icehouse to greenhouse conditions on a fully vegetated Earth, making it a relevant analog for modern Earth systems. High frequency glacioeustatic fluctuation of ~100-200 m during the late Paleozoic are described by some authors in low paleolatitude basins and attributed to the orbitally-driven, waxing and waning of a massive (~20-35 x 106 km2) hypothetical ice sheet. This massive ice sheet is traditionally interpreted to have covered much of southern Gondwana for >100 m.y. Meanwhile, recent studies of high-paleolatitude glacial deposits imply a much more complex pattern …