Abstract
Relict landforms and sediments across former glaciated settings provide information about ice-sheet dynamics and can contribute to the understanding of the behaviour of contemporary ice masses, for which observations are limited in spatial and temporal extent. In this study, we focus on the shelf offshore southwest Ireland, in the Celtic Sea, which was once occupied by the Irish Sea Ice Stream (ISIS), the largest ice stream draining the southern portion of the marine-terminating British-Irish Ice Sheet (BIIS). Newly acquired high-resolution multibeam echosounder, sub-bottom and core data enabled the investigation of the shelf geomorphology and of the sedimentology and chronology of glacial and glacimarine sediments. A suite of drumlins records ice sheet flow from the coastline towards the central part of the shelf in southwest Ireland. Pre-existing highs in the seafloor topography promoted the formation of arcuate and transverse landforms interpreted as a grounding-zone wedge and moraines and they document episodic retreat of the ISIS across this portion of the shelf. Observed lithofacies show consolidated subglacial till and laminated fine muds. The sediments provide evidence of ice grounded ca. 30 km off the south-west Irish coastline with subsequent deglaciation occurring under glacimarine conditions. These new data refine the current reconstructions of the dynamics of the southern BIIS. They reveal for the first time the interplay of marine- and land-based ice and the presence of grounded ice offshore SW Ireland. This study highlights the importance of high-resolution data in revealing palaeo-landscapes as valuable analogues to test possible scenarios of modern ice sheet changes.
| Original language | English |
|---|---|
| Article number | 107655 |
| Pages (from-to) | 1-25 |
| Number of pages | 25 |
| Journal | Quaternary Science Reviews |
| Volume | 291 |
| Early online date | 8 Aug 2022 |
| DOIs | |
| Publication status | Published (in print/issue) - 1 Sept 2022 |
Bibliographical note
Funding Information:This work was carried out as part of C Giglio's PhD project funded by the Department of Education and Learning at Ulster University (Ph.D. studentship 110118). The work was further supported by the NEIF Radiocarbon NRCF010001 (allocation number 2173.0319). We thank Dr Xiaomei Xu at the Keck C cycle AMS Lab, University of, California, for analysing the small radiocarbon samples. High-resolution multibeam echosounder bathymetric and sub-bottom data and sediment cores presented in this study were acquired by the Integrated Mapping for the Sustainable Development of Ireland's Marine Resource (INFOMAR) programme (www.infomar.ie). INFOMAR is a Department of the Environment, Climate and Communications (DECC) funded national Irish seabed mapping programme, jointly managed and delivered by Geological Survey Ireland and Irish Marine Institute. The regional backdrop bathymetry was derived from the EMODnet Bathymetry portal (www.emodnet-bathymetry.eu). We thank the masters, crew and scientists of the R.V. Celtic Voyager and R.V. Celtic Explorer who contributed to the collection of all the datasets shown in this paper. Dr Vincent Rinterknecht, one anonymous reviewer and the input of the JQSR Editor in chief Professor Claude Hillaire-Marcel are acknowledged for their detailed and constructive comments, which helped to significantly improve the manuscript.
Funding Information:
This work was carried out as part of C Giglio's PhD project funded by the Department of Education and Learning at Ulster University (Ph.D. studentship 110118). The work was further supported by the NEIF Radiocarbon NRCF010001 (allocation number 2173.0319). We thank Dr Xiaomei Xu at the Keck C cycle AMS Lab, University of
Publisher Copyright:
© 2022 The Authors
Keywords
- last glacial period
- British-Irish ice sheet
- Irish Sea Ice Stream
- Atlantic Ocean
- Geomorphology
- marine cores
- drumlins
- grounding-zone wedges
- subglacial till
- laminated sediments
