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dc.contributor.authorMackay, Sean Lelanden_US
dc.date.accessioned2016-02-18T20:09:41Z
dc.date.available2016-02-18T20:09:41Z
dc.date.issued2016
dc.identifier.urihttps://hdl.handle.net/2144/14508
dc.description.abstractAntarctic debris-covered glaciers are potential archives of long-term climate change. However, the geomorphic response of these systems to climate forcing is not well understood. To address this concern, I conducted a series of field-based and numerical modeling studies in the McMurdo Dry Valleys of Antarctica (MDV), with a focus on Mullins and Friedman glaciers. I used data and results from geophysical surveys, ice-core collection and analysis, geomorphic mapping, micro-meteorological stations, and numerical-process models to (1) determine the precise origin and distribution of englacial and supraglacial debris within these buried-ice systems, (2) quantify the fundamental processes and feedbacks that govern interactions among englacial and supraglacial debris, (3) establish a process-based model to quantify the inventory of cosmogenic nuclides within englacial and supraglacial debris, and (4) isolate the governing relationships between the evolution of englacial /supraglacial debris and regional climate forcing. Results from 93 field excavations, 21 ice cores, and 24 km of ground-penetrating radar data show that Mullins and Friedman glaciers contain vast areas of clean glacier ice interspersed with inclined layers of concentrated debris. The similarity in the pattern of englacial debris bands across both glaciers, along with model results that call for negligible basal entrainment, is best explained by episodic environmental change at valley headwalls. To constrain better the timing of debris-band formation, I developed a modeling framework that tracks the accumulation of cosmogenic 3He in englacial and supraglacial debris. Results imply that ice within Mullins Glacier increases in age non-linearly from 12 ka to ~220 ka in areas of active flow (up to >> 1.6 Ma in areas of slow-moving-to-stagnant ice) and that englacial debris bands originate with a periodicity of ~41 ka. Modeling studies suggest that debris bands originate in synchronicity with changes in obliquity-paced, total integrated summer insolation. The implication is that the englacial structure and surface morphology of some cold-based, debris-covered glaciers can preserve high-resolution climate archives that exceed the typical resolution of Antarctic terrestrial deposits and moraine records.en_US
dc.language.isoen_US
dc.rightsAttribution-NoDerivatives 4.0 Internationalen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nd/4.0/
dc.subjectGeomorphologyen_US
dc.subjectAntarcticaen_US
dc.subjectClimate changeen_US
dc.subjectCosmogenic nuclide datingen_US
dc.subjectDebris-covered glacieren_US
dc.subjectGround-penetrating radaren_US
dc.subjectOrbital forcingen_US
dc.titleAge, origin and evolution of Antarctic debris-covered glaciers: implications for landscape evolution and long-term climate changeen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2016-02-13T02:21:08Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineEarth & Environmenten_US
etd.degree.grantorBoston Universityen_US


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Except where otherwise noted, this item's license is described as Attribution-NoDerivatives 4.0 International