A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors

Lockhart, Edward; Scourse, James; Praeg, Daniel; Landeghem, Katrien Van; Mellett, Claire L.; Saher, Margot; Callard, Louise; Chiverrell, Richard; Benetti, Sara; Cofaigh, Colm Ó; Clark, Chris D.

doi:10.1016/j.quascirev.2018.08.029

Cited by 24 publications

(34 citation statements)

References 36 publications

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“…Reconstructing palaeo-ice sheet dynamics from offshore sedimentological and stratigraphic archives around the world has become an important topic of focus in the last decade (e.g., Dowdeswell and Ottesen, 2013;Stewart et al, 2013;Jakobsson et al, 2014;Sejrup et al, 2015;Hogan et al, 2016;Lamb et al, 2016;Dove et al, 2017;Greenwood et al, 2017;Streuff et al, 2017;Callard et al, 2018;Lockhart et al, 2018). Understanding how past ice sheets retreated in response to climate warming provides a vital analog for the projection of ice sheet behavior during future climate change (IPCC, 2013).…”

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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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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“…Angle of repose is defined for this study as the steepest angle the seabed sediment is likely to maintain before slope failure from gravity-driven mass wasting and has a well-established correlation with grain size (e.g. Miller and Byrne, 1966); although this attribute is governed by many factors (e.g. grain angularity, sorting and rotation; Miller and Byrne, 1966;Yang et al, 2009), value estimates for coding this sediment property were related to grain size using industrial and academic sources (Table 1).…”

Section: Data Mining Collection and Treatmentmentioning

confidence: 99%

“…Miller and Byrne, 1966); although this attribute is governed by many factors (e.g. grain angularity, sorting and rotation; Miller and Byrne, 1966;Yang et al, 2009), value estimates for coding this sediment property were related to grain size using industrial and academic sources (Table 1). For all attributes, higher numbers were coded for perceived (relative) positive conditions for stability (i.e.…”

Section: Data Mining Collection and Treatmentmentioning

confidence: 99%

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Geological seabed stability model for informing Irish offshore renewable energy opportunities

et al. 2020

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Abstract. Climate change has driven the European Union to propose a reduction in carbon emissions by increasing renewable energy production. Although Ireland is rich in renewable energy, especially offshore wind resources, it is failing to reduce its annual carbon emissions. This study endeavours to improve Ireland's marine spatial planning abilities and offshore renewable energy developments by harmonising and customising a unique geological dataset for incorporation into geospatial assessments of Ireland's continental shelf. A dataset of 1858 points, including 17 new seabed samples collected at strategic sites for this study, is created and used to build a series of geospatial outputs. Data are interpolated with empirical Bayesian kriging to use variogram analyses for probabilistically interpolating coded geological values. The interpolation results are validated through leave-one-out cross-validation and combined with bespoke models of bathymetry and seabed slope using map algebra. The final model reveals areas of relative probable seabed stability based on geological and geomorphological characteristics and is shown to comport with known conditions in several locations. Results suggest that the methods and results presented here could provide useful information to future planning activities and initial site selection assessments.

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“…During ISIS advance at the LGM, glacigenic material was typically deposited directly on top of bedrock and primarily as diamicton, generally referred to as the Irish Sea Till (Ó Cofaigh and Evans, 2001). Having reached its southern extent at the edge of the Celtic Sea Shelf, disintegration of the BIIS began shortly after (Chiverrell et al, 2013(Chiverrell et al, , 2018Praeg et al, 2015;Lockhart et al, 2018;Small et al, 2018;Scourse et al, 2019). Following an initial rapid phase of retreat between Scilly and the Wexford-Pembroke line, by approximately 22.5-21.2 ka BP the ISIS front had reached the study area at the Wicklow Trough (Chiverrell et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Formational history of the Wicklow Trough: a marine‐transgressed tunnel valley revealing ice flow velocity and retreat rates for the largest ice stream draining the late‐Devensian British–Irish Ice Sheet

Coughlan

Tóth

Landeghem

et al. 2020

J Quaternary Science

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The Wicklow Trough is one of several Irish Sea bathymetric deeps, yet unusually isolated from the main depression, the Western Trough. Its formation has been described as proglacial or subglacial, linked to the Irish Sea Ice Stream (ISIS) during the Last Glacial Maximum. The evolution of the Wicklow Trough and neighbouring deeps, therefore, help us to understand ISIS dynamics, when it was the main ice stream draining the former British-Irish Ice Sheet. The morphology and sub-seabed stratigraphy of the 18 km long and 2 km wide Wicklow Trough is described here from new multibeam echosounder data, 60 km of sparker seismic profiles and five sediment cores. At a maximum water depth of 82 m, the deep consists of four overdeepened sections. The heterogeneous glacial sediments in the Trough overlay bedrock, with indications of flank mass-wasting and subglacial bedforms on its floor. The evidence strongly suggests that the Wicklow Trough is a tunnel valley formed by time-transgressive erosional processes, with pressurised meltwater as the dominant agent during gradual or slow ice sheet retreat. Its location may be fault-controlled, and the northern end of the Wicklow Trough could mark a transition from rapid to slow grounded ice margin retreat, which could be tested with modelling.

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A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors

Cited by 24 publications

References 36 publications

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

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

Geological seabed stability model for informing Irish offshore renewable energy opportunities

Formational history of the Wicklow Trough: a marine‐transgressed tunnel valley revealing ice flow velocity and retreat rates for the largest ice stream draining the late‐Devensian British–Irish Ice Sheet

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