Tracking the British-Irish Ice Sheet Retreat and Readvance During the Last Glacial Maximum via Isotope Geochemistry: New Evidence From NW Scotland and the Adjacent Continental Shelf

Taylor, Jennifer, Selby, David, Lloyd, Jeremy, Smeaton, Craig, Best, Louise ORCID: https://orcid.org/0000-0003-3731-054X, Bradwell, Tom, Bendle, James, Mathew, Allison, Yuan, Ling, Podrecca, Luca, Sageman, Bradley, Austin, William, Szidat, Sönke and Simms, Alexander R (2024) Tracking the British-Irish Ice Sheet Retreat and Readvance During the Last Glacial Maximum via Isotope Geochemistry: New Evidence From NW Scotland and the Adjacent Continental Shelf. In: American Geophysical Union AGU Fall Meeting 2024, 9-13 December 2024, Washington, D.C.. (Unpublished)

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Abstract

We have reconstructed the deglacial history of the British-Irish Ice Sheet (BIIS) using a multi-geochemical approach not reliant on microfossil preservation. By evaluating the osmium-isotope (187Os/188Os) system alongside a suite of proxies from three sites we have advanced our understanding of the nature of BIIS retreat and readvance and its impact on relative sea level (RSL). Our record includes: (1) a sediment core from a fjord catchment that records 187Os/188Os values distinct from the open ocean (~1), which we interpret to reflect glacial retreat and readvance following the Last Glacial Maximum (LGM) and Younger Dryas. (2) A second sediment core from an isolation basin near Gairloch the basal glacial sequence of which records distinctly marine osmium values suggesting a glaciomarine regime not previously resolved due to poor microfossil preservation. The basin records a marine osmium signal up core before becoming isolated from the open sea, a development that is recorded in the rapid shift toward more radiogenic 187Os/188Os values which when combined with our age model gives an accurate estimate of RSL fall at this time. (3) Offshore NW Scotland sediment cores record the retreat of the BIIS, basal subglacial tills yield a radiogenic 187Os/188Os signature (~1.5) reflecting increased delivery of radiogenic osmium, due to proximity to the ice margin. This record shifts to less radiogenic values of ~1.2 as the ice margin retreated. In addition, a core recording alternating facies of subglacial till to glaciomarine sediments is reflected in the 187Os/188Os values with subglacial tills recording distinctly more radiogenic 187Os/188Os values than the more distal facies, indicating the sensitivity of the osmium-isotope proxy to more nuanced changes in ice sheet behaviour. Studying the BIIS provides critical insight into the behaviour of mid-latitude ice sheets, their impact on RSL and informs responses to future changes. Our research reveals new insights into the dynamics and temporal behaviour of the BIIS during the LGM that was not fully known. Moreover, through the application of the osmium-isotope system to diverse sites we demonstrate the utility of 187Os/188Os, especially when applied as part of a multiproxy toolkit, as a powerful technique for reconstructing glacially influenced paleoenvironmental records.

Item Type:	Conference or Workshop Item (Poster)
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions:	Schools and Research Institutes > School of Arts, Culture and Environment
Depositing User:	Louise Best
Date Deposited:	19 Dec 2025 12:04
Last Modified:	19 Dec 2025 13:03
URI:	https://eprints.glos.ac.uk/id/eprint/15693

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