IAP-25-076

Reconstructing past ice-sheet retreat and ice-ocean interactions from marine sediment cores.

The greatest uncertainty in projections of sea-level rise stems from the uncertain response of the Antarctic and Greenland ice sheets to future warming (Bamber et al., 2022). While satellite data can constrain ice-sheet and sea-level changes over the last few decades, they do not provide the long-term perspective needed to understand the full range of potential styles and rates of ice-sheet retreat. To improve ice sheet numerical models, it is vital to place modern observations within their longer-term context. To achieve this, the analysis of palaeo-records from previously glaciated regions is essential.

Mid- and high-latitude continental shelves are key sites for studying past ice-sheet behaviour. During the Last Glacial Maximum (about 20,000–26,000 years ago), large ice sheets centred over Fennoscandia and the British Isles coalesced and extended to the continental shelf break, forming the Eurasian Ice Sheet complex (EISC) (Fig. 1). Similar to the Antarctic and Greenland ice sheets today, the western, marine-terminating margin of the EISC was sensitive to both climatic and oceanic forcing. The subsequent deglaciation was a period of rapid ice-sheet retreat and sea-level rise, broadly analogous to current changes. Thus, constraining the timing, style, rate, and drivers of past ice-sheet retreat can improve understanding of ice-sheet behaviour and provide valuable constraints for ice sheet models (e.g., Callard et al., 2020; Clark et al., 2022).

This project aims to reconstruct the behaviour and climate sensitivities of the western margin of the EISC by using sedimentological and biostratigraphic techniques to analyse marine sediment cores of glacigenic and postglacial sediments. It provides an exciting opportunity to analyse new marine cores that will be acquired from Sklinnadjupet on the mid-Norwegian shelf in May 2026 (Fig. 1). This location is particularly significant due to its recently discovered ‘corrugation ridges’, which indicate pulses of extremely rapid ice-sheet retreat (Batchelor et al., 2023). However, limited chronological control currently hinders understanding of the timing and drivers of retreat during the last deglaciation. In this project, the analysis and dating of sediments from marine cores, that will be collected in May 2026, will constrain the timing, rate and drivers of ice-sheet retreat along the mid-Norwegian margin. This will provide vital new empirical constraints to understand the key drivers and mechanisms of ice-sheet change and which can be used to model past and present-day ice-sheet retreat (e.g., Patton et al., 2016; Sejrup et al., 2022).

Depending on the project’s scope (to be determined by the candidate), there is also potential to analyse marine cores acquired as part of the BRITICE-CHRONO project (Fig. 1) (Clark et al., 2022). Although the timing of ice-sheet retreat is well constrained around the British Isles, the palaeoceanographic drivers and ice–ocean interactions operating during the last deglaciation remain poorly constrained. This work could therefore substantially enhance understanding of these processes along the western margin of the British-Irish Ice Sheet.

The key research questions are:
1. What was the timing and rate of past ice-sheet retreat across the continental shelves offshore of mid-Norway and Britain and Ireland?
2. Were ice shelves present during the last deglaciation and if so where were they located?
3. What were the main driving mechanisms and controls on ice-sheet retreat?

This project will exploit new marine sediment cores that will be collected from the mid-Norwegian margin in May 2026 as part of the ‘Timing of Eurasian ice sheet Retreat across the mid-Norwegian margin (TERN)’ project. Analysing these sediments will allow past glacial and palaeoocenaographic changes since the Last Glacial Maximum to be reconstructed. The student will also have access to a large number of existing sediment cores acquired as part of the BRITICE-CHRONO project.

The project will involve laboratory analysis using a combination of sedimentological and biostratigraphic techniques, including:
• Sediment core description and particle size analysis (Newcastle)
• Scanning the sediment cores with state-of-the-art research equipment (e.g., GEOTEK LIBS-Hyperscan (Newcastle), MSCL, Micro-XRF and XCT scanner (Durham).
• Foraminifera analysis (Newcastle)
• Measuring the total organic and inorganic carbon (Jenna Analytica; Newcastle)
• Oxygen isotope analysis
• Geochemistry analysis
The chronology for the sediment cores will be developed using radiocarbon dating of foraminifera. Analyses will be undertaken using the facilities available at Newcastle University, Durham University and via the NERC Environmental Isotope Facility.

The project will also involve computational/statistical analysis and visualisation of the derived datasets.

In addition to Newcastle and Durham universities, this project is a collaboration with Aarhus University, Denmark and the Geological Survey of Norway (NGU) in Trondheim. As such, there is considerable potential for international collaboration and travel.

Year 1

Background reading and literature review; Conduct non-destructive scanning of cores; Identify key core for detailed analysis and plan sampling strategy; Begin foraminiferal analysis; Rangefinder dating of sediment cores by radiocarbon dating; Complete first year progression

Year 2

Conduct destructive methodological techniques on key cores; Visit to NERC isotope facilities; Start to write up results chapters; Plan and begin writing of publications; Attend national conference to present results (e.g., Quaternary Research Association)

Year 3

Complete laboratory analysis of cores; Complete statistical analysis and visualisation of data; Continue developing draft manuscripts for publications; Write and receive feedback on draft chapters of thesis; Attend and present results at an international conference such as EGU (European Geosciences Union) or INQUA (International Union for Quaternary Research).

Year 3.5

Preparation and completion of final chapters for thesis. Submission of papers for publication

The project is designed to give the candidate a broad, cross-disciplinary skillset in marine and glacial geology that includes quantitative palaeoenvironmental analyses. The candidate will be trained and supported in all the methodological techniques.

The candidate will benefit from broad skills training provided in-house at Newcastle (e.g. thesis, paper and grant writing, presentation skills) and from the training provided within the IAPETUS2.

The presence of international collaborators ensures the candidate has excellent opportunities to develop a multidisciplinary research network. Research skills and awareness of ongoing research will be developed through regular participation in Newcastle Physical Geography weekly seminar series, research group meetings, and national and international conferences.

Training is designed to ensure that the candidate becomes a well-rounded scientist who is comfortable working independently and in teams.