Date of Award
Master of Science in Oceanography
The body of this work focuses on the use and revelations of grain size distributions combined with age models and physical properties of sediments, expanding our understanding of the central Arctic Ocean in the Cenozoic Era. The Integrated Ocean Drilling Program’s (IODP) Expedition 302, Arctic Coring Expedition (ACEX), recovered sediment cores from the Lomonosov Ridge, providing the most extensive geologic record of the region ever recovered. This record provides the first opportunity for scientists to directly determine the paleo- ice history of the region, one of high importance to understanding global climate.
Grain size distribution analyses reveal a more consistent ice presence than previously believed possible for the region. The implication suggests a simultaneous transition to a strong cryo-state occurring at both poles. This differs from the previous paradigm of the Antarctic’s cryo-state strengthening millennia earlier than the Arctic. A simultaneous transition to a stronger cryo-state implies a global climatic driver, disavowing theories of current and continental shifts driving one pole than the other.
Due to the premiere opportunity to study the cryo-state of the central Arctic Ocean over a significant portion of the Cenozoic, proxies and analysis techniques needed to be developed and updated. A series of proxies for determining the type and intensity of the cryo-state are presented and employed in paleo- analyses. In addition, predictive relationships between grain size distributions and the physical properties of the sediments developed for these glacio-marine sediments allows more extensive analysis that can be used in the future to determine regions of interest nondestructively to the cores. This will be of significant benefit to future expeditions to the region. Finally, the use of grain size to determine and remove the effects of paleocurrents was updated for the unique depositional environment. Interconnecting other elements of the global climate system to the central Arctic’s cryo-state demonstrates the true interconnectedness of the global system.
Ashmankas, Cristin, "A History of Sea Ice in the Cenzoic Arctic Ocean" (2013). Open Access Master's Theses. Paper 31.