Kurt Joy - PhD Summary
A late Quaternary ice sheet history from cosmogenic dating, South Victoria Land, Antarctica.
My research interests lie in the field of Antarctic paleoclimate, primarily in post LGM reconstructions of ice sheet retreat and its effect on global sea level rise.
My research interests lie in the field of Antarctic paleoclimate, primarily in post LGM reconstructions of ice sheet retreat and its effect on global sea level rise.
An understanding of how the continent has reacted to past climates is necessary to accurately predict the response of its ice sheets to current and future climate changes. The thickness and proximity of the peripheral ice to the continental margin are key to the discussion and relate directly to the volume of ice within the Antarctic ice sheets and their melt water contribution to sea level rise since the last glacial maximum (LGM).
Terrestrial evidence of these changes can be found in ice free areas where glacial landforms, such as moraines, show the extent of former ice advances. The Transantarctic Mountains (TAM) bordering the Ross Sea, present an effective barrier between the East and West Antarctic Ice sheets and are therefore an ideal setting to understand the timing and magnitude of the interactions between them.
One such ice free region in the TAM is the Darwin/Hatherton Glacier. This outlet glacial system drains the East Antarctic Ice Sheet into the Ross Sea through the TAM. At the confluence of the Darwin Glacier and Ross Ice Shelf, Diamond Hill contains evidence of glacial advances at altitudes up to 850 m above the current ice surface.
This site was visited in January 2009 where moraines and glacial erratics were sampled for cosmogenic nuclide dating. The technique assumes that the feature was deposited rapidly and then left exposed at the surface. This exposure leads to the production and accumulation of aluminium and beryllium nuclides in quartz that can be then used to calculate surface exposure times.
While cosmogenic dating has shown much promise in the mid latitudes, a number of complications have arisen with the use of the technique in polar regions. A key problem is the role that cold based glaciations play in the creation of the glacial landscape. Cold based ice is frozen to the underlying bed and is assumed to have minimal erosive capability. A landscape can be completely overrun by this ice and remain untouched, a later glacial recession can then re-expose the fossil landscape leaving little to no evidence of the previous advance. While cosmogenic dating may provide exposure histories of a landscape, the influence of these cold based glaciations adds another layer of complexity to the story.
A timeline of post-LGM glacial retreat in the TAM using cosmogenic dating will be combined with the geological evidence of cold based ice. Reconstructed landscapes and thus ice sheet configurations and thicknesses can then be produced allowing the history of the Antarctic landscape to be view through the lens of cold based glaciations.
My work will contribute fundamental data to an important international debate on the scale of the glaciation in the last ice age. It will help validate ice thickness reconstructions for the ice sheets and provide insights into the timing and nature of the Antarctic contributions to global sea-levels.