Project Description
This project will reconstruct the Late Glacial and Holocene volcanic history represented within the Fletcher ice core from the Fletcher Promontory to southwest of the Ronne Ice Shelf, western Antarctica. The 654.3 m-long ice core was drilled in 2011–2 by the British Antarctic Survey to investigate ice-sea dynamics at the Last Glacial-Interglacial transition (Mulvaney et al. 2014). The small ice sheet is sensitive to climate variability, and the ice core promises to provide a high-resolution record of Holocene external forcing and ice sheet responses. Preservation of tephra from explosive volcanic eruptions within the ice presents opportunities to 1) date and inter-correlate regional ice cores, 2) refine the understanding of volcanic impacts on local to global spatial and temporal scales, and 3) explore the significance of atmospheric circulation patterns contributing to tephra deposition at the sampling site, including the effects of sediment remobilisation on the ice core geochemical record. Previous tephra research in eastern Antarctica has illustrated that high-frequency local Antarctic eruptions have the potential to contribute to volcanic perturbations of the Earth’s radiative balance as well as ice surface albedo (Narcisi et al. 2019).
This project aims to establish the contributions of local (i.e., Antarctic and Southern Ocean), mid- and high-latitude eruptions to the volcanic signal in Antarctic ice, and to examine variability in tephra provenances across climate transitions as a proxy for past environmental change. It will comprise the first extended assessment of volcanic sources in an Antarctic core, guided by a continuous microparticle record that will highlight short-lived peaks of elevated particulate representation. By establishing the sources of tephra represented in the ice core through glass geochemical analysis, including the representation of secondary deposition, the study will investigate variability in tephra provenances and frequency with respect to Late Glacial and Holocene climate oscillations. Specific objectives are to:
- Geochemically characterise all visible tephras to identify their sources
- Evaluate the occurrence of cryptotephras using existing microparticle records, and geochemically characterise selected layers to identify their sources
- Reconstruct continuous volcanic histories for selected time periods, chiefly during the Common Era and periods of climate regime shifts
- Evaluate the occurrence of reworked tephra as a background tephra signal in western Antarctic ice
- Investigate variability in atmospheric circulation dynamics through analysis of source regions over multi-centennial timeframes
The project will integrate with ongoing research by Dr Joe McConnell, Desert Research Institute, who will make available microparticle records and ice samples for analysis.
Essential & desirable candidate skills
Essential: First degree in Palaeoecology, Physical Geography, Earth Sciences or related field. Experience in microscopy, data analysis.
Desirable: Masters degree in a relevant discipline. Experience in tephrochronology, electron microprobe analysis and/or ash-modelling.
Supervisors
Gill PlunkettPrimary Supervisor: | Profile: Gill Plunkett Email: g.plunkett@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Natural and Built Environment |
Matteo SpagnoloSecondary Supervisor: | Profile: Matteo Spagnolo Email: m.spagnolo@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Geosciences |
Andrew NewtonAdditional Supervisor: | Profile: Andrew Newton Email: A.Newton@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Natural and Built Environment |
Additional Supervisor: | Dr Joseph McConnell (Desert Research Institute) will provide access to ice core data and samples, and will advise on the interpretation of associated ice core geochemistry. |
References
Mulvaney, R., Triest, J. & Alemany, O. 2014 The James Ross Island and the Fletcher Promontory ice-core drilling projects. Annals of Glaciology 55, 179–188.
Narcisi, B., Petit, J.R., Delmonte, B., Batanova, V. & Savarino, J. 2019 Multiple sources for tephra from AD 1259 volcanic signal in Antarctic ice cores. Quaternary Science Reviews 210, 164–174.
Expected Training Provision
The candidate’s training will encompass tephra geochemical analysis and interpretation, representing the primary methodology applied in the project. The supervisory team will ensure that the candidate obtains a solid understanding of ice sheet dynamics and atmospheric circulation pattens needed to interpret the broader significance of the tephra results.
Training will be provided at QUB in methods of tephra sample preparation and geochemical analysis. All major element geochemical analysis will be conducted at QUB, while trace element analysis will be performed at an external institution. At Aberdeen, the candidate will receive training in querying ice sheet response to climate perturbations.
Impact
The Fletcher ice core has potential to elucidate the role of the Western Antarctic ice sheet as a trigger for global environmental change at the end of the last glacial period. As an area sensitive to recent climate change, the ice sheet may also reveal climate variability though the Holocene, including responses to short-lived volcanic forcing. The project will provide the first detailed analysis of tephra representation in Antarctic ice. A tephrostratigraphic record offers the possibility not only to date and correlate the Fletcher core with other Antarctic cores, but also to investigate the impact of volcanic forcing through the discernment of local and extra-local volcanism. The provenancing of tephras will facilitate more refined estimates of volcanic aerosol stratospheric loading, thereby enabling more informed reconstructions of past volcanic forcing. Equally, the significance of local eruptions on regional climate and ice albedo can be interrogated.
Proposed Timetable
Year 1 – Sampling plan and preliminary sampling (all visible tephras, and continuous sampling of a multi-decadal sequence to establish relationship of tephra to microparticle peaks). Geochemical analysis. Construction of database for SH tephras.
Year 2 – Detailed sampling of periods of interest. Geochemical analysis. Training in Aberdeen on ice sheet dynamics.
Year 3 – Placement with CASE partner. Data analysis (including ice core chemistry). Interpretation.
Year 4 – Final write-up.
QUADRAT Themes
- earth-systems
Partners
Not applicable at this time.
