Late Cenozoic behaviour of two Transantarctic Mountain outlet glaciers

• Main Author: Jones, Richard
• Format: Thesis
• Language: unknown
• Published: 2015
• Subjects: Geochronology; Geomorphology and Regolith and Landscape Evolution; Glaciology; Palaeoclimatology; Antarctica; Ice sheet; Glaciers; Palaeoclimate; Numerical modelling; Surface exposure dating; School: School of Geography; Environment and Earth Sciences; Unit: Antarctic Research Centre; 040602 Glaciology; 040601 Geomorphology and Regolith and Landscape Evolution; 040605 Palaeoclimatology; 040303 Geochronology; 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts); 960310 Global Effects of Climate Change and Variability (excl. Australia; New Zealand; Antarctica and the South Pacific) (excl. Social Impacts); 960399 Climate and Climate Change not elsewhere classified; Degree Discipline: Physical Geography; Degree Discipline: Geology; Degree Level: Doctoral; Degree Name: Doctor of Philosophy; Antarctic; Pacific; Ross Sea; Skelton Glacier; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.26686/wgtn.17143190.v1; https://figshare.com/articles/thesis/Late_Cenozoic_behaviour_of_two_Transantarctic_Mountain_outlet_glaciers/17143190

Earth’s climate is undergoing dramatic warming that is unprecedented in at least the last ~2000 years. Outlets of the Antarctic ice sheet are experiencing dynamic thinning, terminus retreat and mass loss, however, we are currently unable to accurately predict their future response. The drivers and mechanisms responsible for these observed changes can be better understood by studying the behaviour of outlet glaciers in the geological past. Here, I use cosmogenic nuclide surface-exposure dating and numerical glacier modelling to investigate the past configurations and dynamics of Transantarctic Mountain outlet glaciers, in the Ross Sea sector of Antarctica. Numerical modelling was first applied to understand the present-day and past behaviour of Skelton Glacier. A suite of sensitivity experiments reveal that Skelton Glacier is most susceptible to atmospheric temperature through its affect on basal sliding near the groundingline. Under past climates, large changes occurred in the lower reaches of the glacier, with basal sliding and bedrock erosion predicted in the overdeepened basins during both the Pliocene and Quaternary. Skelton Glacier was likely much shorter and thinner during Pliocene interglacials, with warm-based sliding that extended along most of its length. Informed by the glacier modelling, I applied surface-exposure dating to constrain past fluctuations in the geometry of Skelton Glacier. The lower reaches of the glacier were likely thicker at the Last Glacial Maximum (LGM), supporting the idea of buttressing by grounded ice in the Ross Sea during glacial periods. The glacier then thinned to near-modern surface elevations by ~5.8 ka before present (BP). Multiple isotope analysis (²⁶Al-¹⁰Be) and exposure-burial modelling indicates that Skelton Glacier has fluctuated between interglacial and glacial configurations probably at orbital frequencies since the Miocene. These data record a total of >10 Ma of exposure and 2.5 Ma of burial. An unexpected outcome is that the average cosmogenic production rate ...