Date of Award
Doctor of Philosophy (PhD)
Ocean & Earth Sciences
George R. Whittecar
Numerous studies attempted to reconstruct Arctic paleoclimate, specifically ice mass timing and locations, during glacial maxima. While some regions, like the Barents-Svalbard Ice Sheet (BSIS) are well-studied, they may benefit from a high-resolution paleo proxy. Other regions are highly contested, such as the East Siberian Sea or the presence of a central Arctic Ocean ice mass.
This research uses an Fe-grain provenance method to (1) define how the BSIS behaved during Marine Isotope Stage (MIS) 2, 4, and 6, and when it retreated; (2) determine the presence and ages of Shelf Ice Masses (SIMs) in the Beaufort Sea and East Siberian Sea, or if these SIMs broke up during MIS 2, 4, and 6; and (3) identify whether large ice masses existed in the central Arctic Ocean that might have reduced or prevented ice-rafting during MIS 2, 4, and 6. This study uses elemental compositions of sand-sized Fe-grains within ice rafted debris (IRD) from the deep-sea marine sediment core HLY0503-JPC22 as a proxy for ice transport from 41 circum-Arctic Ocean Source Areas (SAs), and also develops new age model and sedimentation rates through MIS 6. The combined >63 μm IRD and Fe-grain peaks in the last three glacial stages indicate ice sheet collapses near the middle of glacial stages and often again near the termination. MIS 4 is a weak glacial stage with smaller ice sheets than MIS 2 and especially smaller than MIS 6. SIMs on the Beaufort Shelf or East Siberian Shelf are problematic during MIS 2 and 4 but could have existed during MIS 6 where the data are inconclusive. Distinct >1 kyr hiatuses in IRD and Fe-grain transport are only observed in MIS 6, suggesting a central Arctic ice mass existed, and probably consisted of grounded icebergs or shelf ice that reached the Lomonosov Ridge. This study provides an increased understanding of Arctic Ocean ice transport during MIS 2, 4, and 6, for the Barents-Svalbard Ice Sheet in the Eastern Arctic, the East Siberian Sea in the Western Arctic, and the Central Arctic Ocean.
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Cofield, Shannon M..
"History of Ice-Rafting in the Arctic Ocean During Glacial Maxima Through Marine Isotope Stage 6"
(2023). Doctor of Philosophy (PhD), Dissertation, Ocean & Earth Sciences, Old Dominion University, DOI: 10.25777/j3j5-ag82