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C432: Water flow beneath past ice sheets (Lead Supervisor: Kelly Hogan, British Antarctic Survey)

Supervisors: Kelly Hogan (British Antarctic Survey), Julian Dowdeswell (Geography/SPRI), Robert Larter (British Antarctic Survey) and Neil Arnold (Geography/SPRI)

Importance of the area of research:

Basal hydrology is a critical factor controlling the dynamic behaviour of ice sheets and their contribution to sea level change. Geophysical data from formerly glaciated continental shelves reveal seabed channels that indicate past subglacial water flow. Around West Antarctica, such channels have been found almost exclusively eroded into crystalline bedrock in inner continental shelf areas (Ó Cofaigh et al., 2005; Nitsche et al., 2013). In contrast, beneath the southern margin of the former European ice sheet many large “tunnel valleys” were eroded into sedimentary substrates by subglacial water flow (Stewart, 2016). Consideration of the dimensions of channels around West Antarctica and estimates of meltwater production rates suggests water must have been stored in subglacial lakes and discharged episodically (Nitsche et al., 2013), but detailed analysis leading to quantitative constraints on fluxes and repeat periods is lacking. The lack of tunnel valleys in sedimentary substrates around Antarctica suggests that they only form when a threshold in subglacial water flow is exceeded, but once again quantitative estimates are lacking.

Project summary:

The contrasting characteristics of different sub-ice sheet settings provide an opportunity to characterise the basal hydrological regimes associated with different bed topographies and ice dynamic behaviour. Furthermore, subglacial water fluxes associated with the different regimes can be estimated by application of numerical models of ice sheets and subglacial hydrology, with climatic drivers taken from published data and models. Results of the project will lead to an improved understanding of the geomorphological expression of different subglacial water fluxes over different kinds of substrate, and of the effects of basal water on past ice flow.

What the student will do:

The student will examine available geomorphological, geophysical and geological evidence of past subglacial water flow around West Antarctica, including multibeam swath bathymetry, sub-bottom profiles, seismic data and results from analyses of sediment cores collected over the past two decades by BAS, SPRI and collaborators in the United States, Germany and Norway. Comparisons with features formed beneath the southern margin of the European Ice Sheet will be based on published data, model results, and analysis of tunnel valleys in 3D seismic data available from collaborators. The student will also apply numerical models of ice sheets and subglacial hydrology to estimate past meltwater supply and subglacial fluxes. By analyzing the dimensions and geometry of channels, considering the characteristics of their infill revealed by sub-bottom profiles and seismic data, and estimated melt production rates from models, the PhD student will constrain the frequency of subglacial water discharge events in channel systems around West Antarctica, and estimate the threshold flux necessary for formation of tunnel valleys in sedimentary substrates.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Nitsche, F.O., Gohl, K., Larter, R.D., Hillenbrand, C.-D., Kuhn, G., Smith, J.A., Jacobs, S., Anderson, J.B. & Jakobsson, M. 2013. Paleo ice flow and subglacial meltwater dynamics in Pine Island Bay, West Antarctica. The Cryosphere, vol. 7, pp. 249-262, DOI: 10.5194/tc-7-249-2013.

Ó Cofaigh, C., Dowdeswell, J.A., Allen, C.S., Hiemstra, J.F., Pudsey, C.J., Evans, J. & Evans, D.J.A. 2005. Flow dynamics and till genesis associated with a marine-based Antarctic palaeo-ice stream. Quaternary Science Reviews, vol. 24, pp. 709-740, DOI: 10.1016/j.quascirev.2004.10.006.

Stewart, M.A. 2016. Assemblage of buried and seabed tunnel valleys in the central North Sea: from morphology to ice-sheet dynamics. In: Dowdeswell, J.A., Canals, M., Jakobsson, M., Todd, B.J., Dowdeswell, E.K. & Hogan, K.A. (eds) Atlas of Subglacial Landforms: Modern, Quaternary and Ancient. Geological Society, London, Memoirs, vol. 46, pp. 317-320, DOI: 10.1144/M46.140.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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