Advance and retreat of the marine-terminating Irish Sea Ice Stream into the Celtic Sea during the Last Glacial: Timing and maximum extent

Scourse, James; Saher, Margot; Landeghem, Katrien Van; Lockhart, Edward; Purcell, Catriona; Callard, Louise; Roseby, Zoë A.; Allinson, Ben; Pieńkowski, Anna J.; Ó'Cofaigh, Colm; Praeg, Daniel; Ward, Sophie; Chiverrell, Richard; Moreton, Steven G.; Fabel, Derek; Clark, Chris D.

doi:10.1016/j.margeo.2019.03.003

Cited by 36 publications

(68 citation statements)

References 56 publications

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“…During the Last Glacial Maximum (LGM) (~26 ka) ice cover of the Irish Sea was complete; the Irish Sea Ice Stream (ISIS) extended southwards beyond the Scilly Isles (Smedley et al 2017;Scourse et al 2019). As there is no reason to suppose that the emanation of Westphalian gas was interrupted by surface conditions during the glacial period, it is assumed that gas accumulated beneath the ice, possibly as gas hydrates formed as a result of increased pressures associated with ice loading.…”

Section: Discussionmentioning

confidence: 99%

The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance

et al. 2019

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The Croker Carbonate Slabs, in the UK sector of the Irish Sea, has shallow (70 to 100 m) water, strong (> 2 knot) tidal currents, coarse mobile surficial sediments and the most extensive methane-derived authigenic carbonate (MDAC) known in European waters. Multi-disciplinary studies (2004 to 2015) were commissioned specifically to document the benthic habitat, and have resulted in the designation of this site as a Marine Protected Area (MPA) under the European Commission’s Habitats Directive as an example of “Submarine structures formed by leaking gases”. However, this paper is focussed on the geoscience aspects of the site: the mineralogy and isotopic composition of the MDAC, its formation and age. It considers the implications of these findings with respect to the timing of the deglaciation of the area since the Last Glacial Maximum (LGM), and the environmental implications of the seepage of methane from the site over a period of at least 17,000 years. Carbon isotope ratios (δ13 C − 34 to − 54‰) confirm that the carbonate minerals (high-Mg calcite and aragonite) result from the anaerobic oxidation of methane. Widespread shallow gas within post-glacial sediments is sourced from underlying coal-bearing Carboniferous strata. Geophysical (side-scan sonar and multi-beam echo sounder) and visual surveys show that the MDAC occurs as isolated lumps, continuous pavements, and cliffs < 6 m tall, which post-date the post-glacial sediments, but are in places covered by a veneer of coarse mobile surficial sediments. U-Th dates (17,000 ± 5500 to 4000 ± 200 BP) suggest continual MDAC formation since the last glacial maximum, and constrain the postglacial sea level rise in this part of the Irish Sea; the site must have been submarine before MDAC formation started, whether or not methane was escaping. Visual and acoustic evidence of gas seepage is limited, but methane concentrations in the water are high (< 21.4 nmol l−1) and suggest present-day export to the atmosphere. It is also implied that significant methane release to the atmosphere occurred immediately after the retreat of the ice that covered the site during the LGM until 21.9 to 20.7 ka BP.

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Section: Discussionmentioning

confidence: 99%

The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance

et al. 2019

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“…Particular focus has been on understanding the dynamics of the British-Irish Ice Sheet during Marine Isotope Stage (MIS) 2 (∼30 -11.7 ka BP) and, as such, it has become one of the best constrained palaeo-ice sheets (Clark et al, 2004(Clark et al, , 2012(Clark et al, , 2018. The extent and dynamics of northern and western sectors of the ice sheet has become well understood through both data and modeling approaches (Bradwell et al, 2007;Boston et al, 2010;Davies et al, 2011;Bradwell and Stoker, 2015;Peters et al, 2016;Smedley et al, 2017;Callard et al, 2018;Chiverrell et al, 2018;Gandy et al, 2018;Scourse et al, 2019). Confluence and interaction of the British-Irish and Scandinavian ice sheets in the North Sea Basin is unclear, and the maximum extent and dynamics of the ice sheet in the North Sea are still poorly constrained (Phillips et al, 2017b), with few studies into the controls of ice sheet advance and retreat (Cotterill et al, 2017a;Phillips et al, 2018;Roberts et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Left High and Dry: Deglaciation of Dogger Bank, North Sea, Recorded in Proglacial Lake Evolution

et al. 2019

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Reconstructions of palaeo-ice sheet retreat in response to climate warming using offshore archives can provide vital analogs for future ice-sheet behavior. At the Last Glacial Maximum, Dogger Bank, in the southern North Sea, was covered by the Eurasian Ice Sheet. However, the maximum extent and behavior of the ice sheet in the North Sea basin is poorly constrained. We reveal ice-marginal dynamics and maximum ice extent at Dogger Bank through sedimentological and stratigraphic investigation of glacial and proglacial lake sediments. We use a large, integrated subsurface dataset of shallow seismic reflection and geotechnical data collected during windfarm site investigation. For the first time, an ice stream is identified at Dogger Bank, based on preserved subglacial bedforms, eskers and meltwater channels. During ice-sheet advance, a terminal thrustblock moraine complex formed, whose crest runs approximately north-northeast to south-southwest. Subsequent ice stream shutdown caused stagnation of ice, and rapid retreat of the ice-sheet margin. The moraine complex, and outwash head from an adjacent ice-sheet lobe to the west, dammed a large (approximately 750 km 2) proglacial lake. Subsequent sedimentation infilled the lake with 30 m of glacial outwash sediments. A lobate subaqueous fan formed at the ice-sheet margin, which thins toward the southeast with iceberg scours and ice-rafted debris at the base, and is onlapped by lake sediments calibrated to core as alternating clay and silt laminae, interpreted to be varves. The lake became isolated from the retreating ice-sheet margin, and ice-sheet retreat slowed. Sediment-laden meltwater was supplied to the ice-distal proglacial lake for c. 1500-2000 years. Subsequent ice-sheet retreat off Dogger Bank was more rapid due to the negative subglacial slope. The stepped retreat of rapid downwasting, slow retreat, and a final rapid phase off Dogger Bank occurred after the LGM at around 27 ka and before formation of a ribbon lake, dated previously to 23 ka and approximately 60 m lower in elevation, formed to the north of Dogger Bank. The complicated stratigraphic architecture revealed through these data improves forecasting of ground conditions for turbine footings at Dogger Bank, an important step in the provision of clean, sustainable energy.

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“…Further north, recent comprehensive mapping (Chiverrell et al, 2016) in lowland Lancashire shows that the landform signature reflects the uncoupling and realignment of adjacent and increasingly separate ice lobes that developed during deglaciation between 21 and 17.3 ka, showing the interaction of a dominant ISG with smaller ice masses draining eastern Cumbria and the Pennines. The geochronological data published to date suggest that rates of ice-marginal retreat in the eastern ISB were slower than the Irish Sea Ice Stream (ISIS) to the west (Chiverrell et al, 2013(Chiverrell et al, , 2016(Chiverrell et al, , 2018Smedley et al, 2017a;Small et al, 2018;Scourse et al, 2019). These differences in the pace of retreat have been attributed to the absence of ice streaming and the terrestrial nature of the eastern terminating ice lobe (Chiverrell et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

Chiverrell¹,

Thomas²,

Burke³

et al. 2020

Preprint

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<p>Comprehensive mapping and the Briticechrono geochronology provides a reconstruction of the last advance and retreat of the only land-terminating ice lobe of the western British Irish Ice Sheet. The Irish Sea Glacier was fed by ice from Lake District, Irish Sea and Wales, and extended to maximum limits in the English Midlands. During ice retreat after 27 kyrs, a series of reverse bedrock slopes rendered proglacial lakes endemic in the land-system. Not resembling the more extensive definitions of the classical &#8216;Glacial Lake Lapworth&#8217;, these ice contact lakes were smaller time transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, OSL bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples, and constrained for the Irish Sea Glacier a post 30ka ice maximum advance, 26.5&#177;1.8ka maximum extent, and 25.3&#177;1.6 to 20.6&#177;2.2ka retreat vacating the region. With retreat of the Irish Sea Glacier an opportunistic Welsh re-advance 19.7&#177;2.5ka took advantage of the vacated space and rode over Irish Sea Glacier moraines. Our geomorphological chronosequence shows a glacial system forced by climate, but mediated by piracy of ice sources shared with the larger and marine terminating Irish Sea Ice Stream to the west. The Irish Sea Glacier underwent changes flow regime and fronting environments driven by stagnation and decline as the primary impetus to advance was diverted. Ultimately, the glacier of the English Midlands display complex uncoupling and realignment during deglaciation and ice margin retreat towards upland hinterlands ~17.8 kyrs (Lake District and Pennines) and asynchronous behaviour as individual adjacent ice lobes became increasingly important in driving the landform record.</p>

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Advance and retreat of the marine-terminating Irish Sea Ice Stream into the Celtic Sea during the Last Glacial: Timing and maximum extent

Cited by 36 publications

References 56 publications

The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance

The Croker Carbonate Slabs: extensive methane-derived authigenic carbonate in the Irish Sea—nature, origin, longevity and environmental significance

Left High and Dry: Deglaciation of Dogger Bank, North Sea, Recorded in Proglacial Lake Evolution

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

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