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Ice sheets, fans and drifts: how glacial-marine processes and climate change have built the West Antarctic continental margin


Project Description

The West Antarctic Ice Sheet has advanced and retreated across its adjacent continental margin many times during the Neogene and Quaternary, possibly collapsing entirely during the last interglacial (Dutton et al., 2015). This has produced thick sequences of glacial-marine sediments that contain long-term records of ice-sheet history, Southern Ocean circulation and climatic change (e.g. Hernández-Molina et al., 2017). However, there is significant variability in the gross morphology and internal architecture of the margin and unravelling the factors dominating glacial-marine sediment delivery, and its relationships with climatic forcings, remains difficult. These factors include ice-sheet advance/retreat cycles that control the periodicity of sediment delivery, basal meltwater fluxes, drainage basin geology, and dominant transport mechanisms. Inferences drawn from understanding this unique submarine glacial landscape can provide insights into the growth and decay of continental ice sheets and ice-ocean-climate interactions. Knowledge of these connections is critical for our understanding of the vulnerability of the modern Antarctic Ice Sheet to climatic change.

The project will use marine geoscientific datasets to study two major components of the West Antarctic margin: (i) the Belgica Trough Mouth Fan (Dowdeswell et al., 2008), and (ii) large, deep-sea sediment drifts beyond the fan (Rebesco et al., 1996). Both of these are made up of glacially-sourced material but reflect formation and transport mechanisms related to different ice/ocean/climatic forcings. The fan reflects the activity of a grounded ice sheet on the shelf whereas the drifts are constructed of fine-grained components from turbidity currents entrained in a deep contour current that flows along the margin. Using high-resolution multichannel seismic lines from four sediment drifts and the fan, integrated with swath bathymetry data, sub-bottom profiles and sediment cores the project will deconvolve the glacial/marine/climatic factors controlling West Antarctic margin development.

The student will be involved with the processing and analysis of marine geoscientific datasets including reflection seismic profiles, seafloor bathymetry and core sedimentology. This will involve detailed morphological measurements and seismic analyses (amplitude distribution, bottom simulating reflectors, sequence mapping) to determine the evolution of both the fan and the drifts. This will be integrated with the surface morphology of these features revealed by swath bathymetry, to examine erosion and transport processes at a variety of scales from the individual drift flanks to full ocean margin (shelf-slope) transects. There is potential for the student to get involved in numerical modelling of glacial sediment transport/delivery and to use their results from marine geophysical data to test model outputs.

Funding Notes

UK and EU students who meet the UK residency requirements will be eligible for a full NERC studentship. Students from EU countries who do not meet the residency requirements may still be eligible for a fees-only award. More information can be found in the UKRI Training Grant Terms and Conditions
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References

Dowdeswell, J.A., Ó Cofaigh, C., Noormets, R., Larter, R.D., Hillenbrand, C.-D., Benetti, S., Evans, J., Pudsey, C.J., 2008. A major trough-mouth fan on the continental margin of the Bellingshausen Sea, West Antarctica: the Belgica Fan. Marine Geology 252, 129-140. doi:10.1016/j.margeo.2008.03.017.
Hernández-Molina, F.J., Larter, R.D., Maldonado, A., 2017. Neogene to Quaternary stratigraphic evolution of the Antarctic Peninsula, Pacific Margin offshore of Adelaide Island: Transitions from a non-glacial, through glacially-influenced to a fully glacial state. Global and Planetary Change 156, 80–111. doi:10.1016/j.gloplacha.2017.07.002.
Rebesco, M., Larter, R.D., Camerlenghi, A. & Barker, P. F. 1996. Giant sediment drifts on the continental rise west of the Antarctic Peninsula. Geo-Marine Letters, 16, 65-75. doi:10.1007/BF02202600.

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