Ice dynamics of the Darwin-Hatherton glacial system, Transantarctic Mountains, Antarctica

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dc.contributor.authorRiger-Kusk, Mette
dc.date.accessioned2012-05-21T02:05:02Z
dc.date.available2012-05-21T02:05:02Z
dc.date.issued2011en
dc.description.abstractThe Darwin-Hatherton glacial system (DHGS) drains from the East Antarctic Ice Sheet (EAIS) and through the Transantarctic Mountains (TAM) before entering the Ross Embayment. Large ice-free areas covered in glacial sediments surround the DHGS, and at least five glacial drift sheets mark the limits of previous ice extent. The glacier belongs to a group of slow-moving EAIS outlet glaciers which are poorly understood. Despite this, an extrapolation of a glacial drift sheet boundary has been used to determine the thickness of the EAIS and the advanced West Antarctic Ice Sheet (WAIS) during the Last Glacial Maximum (LGM). In order to accurately determine the past and present contributions of the Antarctic ice sheets to sea level changes, these uncertainties should be reduced. This study aims to examine the present and LGM ice dynamics of the DHGS by combining newly acquired field measurements with a 3-D numerical ice sheet-shelf model. The fieldwork included a ground penetrating radar survey of ice thickness and surface velocity measurements by GPS. In addition, an extensive dataset of airborne radar measurements and meteorological recordings from automatic weather stations were made available. The model setup involved nesting a high-resolution (1 km) model of the DHGS within a lower resolution (20 km) all-Antarctic simulation. The nested 3-D modelling procedure enables an examination of the impact of changes of the EAIS and WAIS on the DHGS behaviour, and accounts for a complex glacier morphology and surface mass balance within the glacial system. The findings of this study illustrate the difference in ice dynamics between the Darwin and Hatherton Glaciers. The Darwin Glacier is up to 1500 m thick, partially warm-based, has high driving stresses (~150 kPa), and measured ice velocities increase from 20-30 m yr⁻¹ in the upper parts to ~180 m yr⁻¹ in the lowermost steepest regions, where modelled flow velocities peak at 330 m yr⁻¹. In comparison, the Hatherton Glacier is relatively thin (<900 m), completely cold-based, has low driving stresses (~85 kPa), and is likely to flow with velocities <10 m yr⁻¹ in most regions. It is inferred that the slow velocities with which the DHGS flows are a result of high subglacial mountains restricting ice flow from the EAIS, large regions of frozen basal conditions, low SMB and undulating bedrock topography. The model simulation of LGM ice conditions within the DHGS implies that the ice thickness of the WAIS has been significantly overestimated in previous reconstructions. Results show that the surface of the WAIS and EAIS away from the TAM would have been elevated 600-750 and 0-80 m above present-day levels, respectively, for the DHGS to reach what was inferred to represent the LGM drift sheet limit. Ultimately, this research contributes towards a better understanding of the dynamic behaviour of slow moving TAM outlet glaciers, and provides new insight into past changes of the EAIS and WAIS. This will facilitate more accurate quantifications of contributions of the WAIS and EAIS to changes in global sea level.en
dc.identifier.urihttp://hdl.handle.net/10092/6602
dc.identifier.urihttp://dx.doi.org/10.26021/8928
dc.language.isoen
dc.publisherUniversity of Canterbury. Geographyen
dc.relation.isreferencedbyNZCUen
dc.rightsCopyright Mette Riger-Kusken
dc.rights.urihttps://canterbury.libguides.com/rights/thesesen
dc.subjectAntarcticaen
dc.subjectWest Antarctic Ice Sheeten
dc.subjectEast Antarctic Ice Sheeten
dc.subjectIce Sheeten
dc.subjectglaciologyen
dc.subjectTransantarctic Mountainsen
dc.subjectDarwin Glacieren
dc.subjectHatherton Glacieren
dc.subjectGround Penetrating Radaren
dc.subjectglacier modellingen
dc.subjectice dynamicsen
dc.subjectglacier changeen
dc.subjectLast Glacial Maximumen
dc.subjectglacial sedimentsen
dc.subjectmass balanceen
dc.subjectgrounding lineen
dc.subjectblue ice areasen
dc.titleIce dynamics of the Darwin-Hatherton glacial system, Transantarctic Mountains, Antarcticaen
dc.typeTheses / Dissertations
thesis.degree.disciplineGeographyen
thesis.degree.grantorUniversity of Canterburyen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen
uc.bibnumber1772329en
uc.collegeFaculty of Scienceen
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