Seabed geomorphology of the Porcupine Bank, West of Ireland

Thébaudeau, Benjamin; Monteys, Xavier; McCarron, Stephen; O’Toole, Ronan; Caloca, Silvia

doi:10.1080/17445647.2015.1099573

Cited by 7 publications

(11 citation statements)

References 19 publications

(23 reference statements)

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“…King et al, 1996;Stravers and Powell., 1997) although the thick laminated mud sequences recovered in core 194VC implies deposition also involved meltwater delivery. The seafloor incisions are consistent with iceberg scouring (Sacchetti et al, 2015;Thébaudeau et al, 2016).…”

Section: Mid-inner Shelf Linesinterpretationmentioning

confidence: 67%

Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland

Callard

Cofaigh

Benetti³

et al. 2020

Marine Geology

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During the Last Glacial Maximum, the British-Irish Ice Sheet extended across the continental shelf offshore of Galway Bay, western Ireland, and reached a maximum westward extent on the Porcupine Bank. New marine geophysical data, sediment cores and radiocarbon dates are used to constrain the style and timing of ice margin retreat across the mid to inner-shelf. Radiocarbon dated shell fragments in subglacial till on the mid-shelf constrains this ice advance to after 26.4 ka BP. Initial retreat was underway before 24.4 ka BP, significantly earlier than previous reconstructions. Grounding-line retreat was accompanied by stillstands 2 and/or localised readvances of the grounding-line. A large composite Mid-Shelf Grounding-Zone Complex marks a major grounding-line position, with the ice grounded and the margin oscillating at this position by, and probably after, ka BP. Deglaciation of the continental shelf was complete by 17.1 cal. ka BP, but the ice sheet may have retained a marine margin until c. 15.3 ka BP. Ice sheet retreat occurred in a glacimarine setting and the ice margin was fringed by a floating ice-shelf. Collectively, this evidence indicates a dynamic and oscillatory marine-terminating ice sheet offshore of western Ireland during the last deglaciation.

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Section: Mid-inner Shelf Linesinterpretationmentioning

confidence: 67%

Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland

Callard

Cofaigh

Benetti³

et al. 2020

Marine Geology

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“…Benetti et al 2010;Dunlopet al2010;Clarket al2012). Furthermore, the area covered by the last BIIS is now thought to have been considerably greater than previously envisioned, with glacial landforms and sediments recorded at many localities near the continental shelf break and across the North Sea Basin Praeg et al 2015;Th ebaudeau et al 2015;Sejrup et al 2016). The purpose of this paper is to present an updated glacial map and geodatabase of glacial landforms relating to the BIIS, and to highlight the evidence gathered in the 15 years since the and syntheses.Theaimofthiscompilationisthesameas that of the original version: to present the geomorphological evidence pertinent to the behaviourof the whole ice sheet, and with emphasis on the primary observations rather than wider interpretations based upon them.…”

mentioning

confidence: 98%

BRITICE Glacial Map, version 2: a map and GIS database of glacial landforms of the last British–Irish Ice Sheet

Clark

Ely

Greenwood

et al. 2017

Boreas

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118

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During the last glaciation, most of the British Isles and the surrounding continental shelf were covered by the BritishIrish Ice Sheet (BIIS). An earlier compilation from the existing literature (BRITICE version 1) assembled the relevant glacial geomorphological evidence into a freely available GIS geodatabase and map (Clark et al. 2004: Boreas 33, 359). New high-resolution digital elevation models, of the land and seabed, have become available casting the glacial landform record of the British Isles in a new light and highlighting the shortcomings of the V.1 BRITICE compilation. Here we present awholesale revision of the evidence, onshore and offshore, to produce BRITICE version 2, which now also includes Ireland. All published geomorphological evidence pertinent to the behaviour of the ice sheet is included, up to the census date of December 2015. The revised GIS database contains over 170 000 geospatially referenced and attributed elements -an eightfold increase in information from the previous version. The compiled data include: drumlins, ribbed moraine, crag-and-tails, mega-scale glacial lineations, glacially streamlined bedrock (grooves, roches moutonn ees, whalebacks), glacial erratics, eskers, meltwater channels (subglacial, lateral, proglacial and tunnel valleys), moraines, trimlines, cirques, trough-mouth fans and evidence defining ice-dammed lakes. The increased volume of features necessitates different map/database products with varying levels of data generalization, namely: (i) an unfiltered GIS database containing all mapping; (ii) a filtered GIS database, resolving data conflicts and with edits to improve geo-locational accuracy (available as GIS data and PDF maps); and (iii) a cartographically generalized map to provide an overviewof the distribution and types of features at the ice-sheet scale that can be printed at A0 paper size at a 1:1 250 000 scale. All GIS data, the maps (as PDFs) and a bibliography of all published sources are available for download from: https://www.sheffield.ac.uk/geography/staff/clark_chris/britice. Palaeo-ice sheets provide the opportunity to study icesheet behaviour over a longer time period (10 000s of years) than can be achieved by studying current ice sheets (10s of years) thereby permitting exploration of the long-term role of ice sheets in the climate system. The extent, geometry and dynamics of palaeo-ice sheets can be reconstructed from the geomorphological and geological evidence they leave behind, with the mapping, logging and description of such evidence being the vital ingredients. For many palaeo-ice sheets, such as the British-Irish Ice Sheet (BIIS), the accumulation of evidence at individual field-sites has been ongoing for well over 100 years (e.g. Geikie 1894) yielding thousands of publications. Using such work to build local to regional reconstructions of ice dynamics is feasible, but at the ice-sheet scale the volume of information becomes unmanageable. Often the information is spread across so many publications and across many decades of work, where...

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“…Todd et al, 2007). On Irish National Seabed Survey high resolution multibeam bathymetric data (Cullen, 2003), iceberg scours are also observed on the contemporary seabed, occurring throughout the region in water depths of 180-575 m (Sacchetti et al, 2012;Thébaudeau et al, 2015) (Fig. 1).…”

Section: Accepted Manuscriptmentioning

confidence: 96%

A Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland: The Connemara Fan

et al. 2018

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Citation for published item:wgrronD tephen nd regD hniel nd gofighD golm ¡ yF nd wonteysD vier nd h¡ eudeuD fenjmin nd grvenD uiern nd qD wuhmmd wudsr nd govD endre @PHIVA 9e lioEleistoene sediment wedge on the ontinentl shelf west of entrl srelnd X the gonnemr pnF9D wrine geologyFD QWW F ppF WUEIIRF Further information on publisher's website: httpsXGGdoiForgGIHFIHITGjFmrgeoFPHIVFHPFHHW Publisher's copyright statement: c 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract Glacigenic sediment fans recording shelf edge deposition from marineterminating ice sheets have previously been recognised along the NW European continental margin from Svalbard to as far south as Donegal, off north-west Ireland. Here we present evidence of a previously unrecognised partially glacially-fed Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland using 2D and 3D seismic reflection data correlated to a commercial borehole. The 'Connemara Fan' covers a shelf area of approximately 9000 km 2 in water depths of 125 -310 m, extending westwards into the Porcupine Seabight from the Irish Mainland Shelf. The wedge comprises up to 160 m of sediment that culminates in a prominent moraininc ridge at seabed and contains two discordant reflection surfaces (R1 and 2) that subdivde it into three seismic units (SU1-3). Stratigraphic boreholes 27/24-2 and 2A located on the inner shelf show that the lower unit (SU1) is composed of Pliocene marine sediments, while SU2 and 3 comprise glacially influenced facies of Quaternary age. Extracts from a 3D seismic data volume within the central part of the fan show channels within the Pliocene succession, while iceberg scours are observed on the R1 and R2 reflectors. The Connemara Fan is inferred to record sediment supply from central western Ireland, with Quaternary units probably recording at least two glacial advance-retreat cycles with ice sheets repeatedly grounding across the inner (Irish Mainland) shelf. Our findings extend the range of glacially-influenced grounding line depocentres southwards along the NW European continental margin.

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Seabed geomorphology of the Porcupine Bank, West of Ireland

Cited by 7 publications

References 19 publications

Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland

Oscillating retreat of the last British-Irish Ice Sheet on the continental shelf offshore Galway Bay, western Ireland

BRITICE Glacial Map, version 2: a map and GIS database of glacial landforms of the last British–Irish Ice Sheet

A Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland: The Connemara Fan

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