IAP2-23-091

Late Quaternary glaciation and ice sheet-ocean interaction on the Faroes-Shetland margin

Understanding past ice sheet extent and the timing of ice sheet advance and retreat is fundamental in improving our ability to predict the future response of modern ice sheets to ongoing climate change. This PhD project utilises recently collected marine sediment cores and geophysical data to reconstruct the extent, flow dynamics, and timing of Late Quaternary glaciation on the Faroes-Shetland continental margin as well as the nature of glacigenic sediment delivery from shelf to deep-sea (Fig. 1). Recent work has allowed a detailed reconstruction of the extent and chronology of the last British-Irish Ice Sheet (Clark et al., 2022), but across the Faeroes-Shetlands margin there is a major gap in our knowledge and understanding of glacial extent, sedimentation and chronology. This is particularly the case on the continental shelf of the Faroes where there has been relatively little previous work on the glacial history. The limited existing understanding is that ice probably expanded across the Faroes shelf on more than one occasion during the Quaternary (Nielsen et al. 1997; Humlum et al., 2023), but the extent of these different ice advances, their timing as well as their flow dynamics (e.g., were there palaeo-ice streams on the Faroes shelf during the Last Glacial Maximum?) remain largely unknown. Similarly the interaction and timing between an ice cap over the Faroes with that of ice over the Shetlands is unknown.

This PhD project will address the above problem by utilising an exceptional suite of marine sediment cores and geophysical data collected on a recent research expedition of the RRS Sir David Attenborough to the Faroes-Shetland margin. The dataset comprises sediment cores collected from the Faroes shelf, the deep-water Faroes Shetland Channel and the continental slope adjoining the Shetlands (Fig. 1). It also comprises extensive geophysical data on seafloor geomorphology and sub-surface acoustic stratigraphy and sediment thickness.

The project seeks to answer the following research questions: (1) What was the extent of the last glaciation on the continental shelf surrounding the Faroe Islands as well as the timing of its subsequent retreat? (2) What is the timing and nature of Late Quaternary glacigenic sediment delivery to the Foula Sediment Wedge offshore of Shetland (Caruso et al., 2022)? (3) What was the pattern and nature of glacimarine sedimentation on the slope offshore of the Sandoy Trough on the Faroes continental shelf? (4) What is the timing, source and significance of ice-rafted debris delivery to the deep-water Faroes-Shetland Channel and can this be used to investigate the phasing of ice sheet advance and retreat on the Faroes and Shetlands?

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Image Captions

Figure 1: Left panel – The study area of the Faroes-Shetland margin showing the lines along which data acquisition took place during cruise SDA030 in 2023. Right panel – corer deployment over the side of the RRS Sir David Attenborough on the Faroes continental shelf.

Methodology

Data for the project comprise existing marine sediment cores and geophysical datasets that were collected during a British Antarctic Survey/Durham University research cruise on the UK Polar research ship the RRS Sir David Attenborough in 2023. While this project will use data and core materials already collected, the intention is for the student to participate in a marine research cruise during the course of the PhD. Time will also be spent at British Antarctic Survey during the course of the project to analyse and interpret the geophysical data.

Marine geophysical data comprise multibeam swath bathymetric imagery of seafloor morphology which will allow the reconstruction of former ice sheet extent, flow direction and flow dynamics. The multibeam data are supplemented with shallow acoustic (sub-bottom profiler) data on acoustic stratigraphy and sediment thickness. Sediment coring during the cruise utilised gravity, piston and box/multi- corers to obtain samples of subglacial, deglacial and postglacial sediments from the continental shelf and slope offshore of the Faroes, the deep water of the Faroes-Shetland Channel and the continental slope adjoining the Shetland shelf. The cores will be analysed for grain size, sedimentary structures, shear strength, and micro- and macrofaunal content. Selected samples will be dated using radiocarbon to obtain a chronology of Late Quaternary ice sheet advance and retreat and palaeoceanographic change.

Project Timeline

Year 1

Analysis of existing marine geophysical data and sediment cores from Faroes-Shetland continental margin.

Year 2

Continued analysis of existing marine geophysical data and sediment cores from Faroes-Shetland continental margin and submission of samples for radiocarbon dating. Presentation of results at national conference – Quaternary Research Association, Annual Discussion Meeting. Participation in marine research cruise. This could also take place at the end of Year 1 – it will depend on cruise timing.

Year 3

Completion of all data analysis and interpretation. Commence thesis writing. Presentation of results at major international conference – INQUA 2027 India.

Year 3.5

Completion and submission of thesis. Finalise manuscripts for publication. Presentation of results at national conference – International Glaciological Society, British Branch Meeting.

Training
& Skills

The student will receive training in the description, analysis and interpretation of multibeam swath bathymetric datasets, sub-bottom profiler records and marine sediment cores. Broader, transferrable skills training will be provided via Durham University’s award-winning Career and Research Development (CAROD) group with courses, for example, in writing for publication, thesis writing, presentation skills. The student will also benefit from cross-disciplinary training provided through IAPETUS. The student will be a member of the ‘Sea Level, Ice Sheets and Climate Research Cluster in Geography’. It is also intended that the student will participate in a research cruise during the course of the PhD to experience the hands-on data collection of sediment cores at sea.

References & further reading

• Bradwell, T., Small, D., Fabel, D., Chiverrell, R.C., Clark, C.D., Saher, M., Dove, D., Callard, S.L., Burke, M.J., Moreton, S.G., Medialdea, A., Batman, M.D., Roberts, D.H., Golledge, N., Finlayson, A., Morgan, S., and Ó Cofaigh, C. (2021). Pattern, style and timing of British–Irish Ice Sheet retreat: Shetland and northern North Sea sector. Journal of Quaternary Science, v. 36, 681-722.

• Caruso S., Maselli, V., Rea, B. and Spagnolo, M., (2022). Deep-water sedimentation processes on a glaciated margin: The Foula Wedge trough mouth fan, West of Shetland. Marine Geology, v. 446, https://doi.org/10.1016/j.margeo.2022.106769

• Clark, C.D., Ely, J.C., Hindmarsh, R.C.A, Bradley, S., Igneczi, A., Fabel, D., Ó Cofaigh, C., Chiverrell, R.C., Scourse, J.D., plus 27 others (2022). Growth and retreat of the last British-Irish Ice Sheet (31 to 15 ka BP); the BRITICE-CHRONO reconstruction. Boreas, v. 51, 699-758.

• Humlum, O., Christiansen, H.H., Mortensen L.E., Stuart, F. and Stone, J. (2022). Weichselian Glaciation of the Faroe Islands. https://2dgf.dk

• Nielsen, T., Rasmussen, T.L., Ceramicola, S., and Kuijpers, A., (1997). Quaternary sedimentation, margin architecture and ocean circulation variability around the Faroe Islands, North Atlantic. Marine Geology, v. 26, 1016-1036.

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