Devising quality assurance procedures for assessment of legacy geochronological data relating to deglaciation of the last British-Irish Ice Sheet

Small, David; Clark, Chris D.; Chiverrell, Richard; Smedley, Rachel; Bateman, Mark D.; Duller, G.A.T.; Ely, Jeremy C.; Fabel, Derek; Medialdea, Alicia; Moreton, Steven G.

doi:10.1016/j.earscirev.2016.11.007

Cited by 57 publications

(81 citation statements)

References 157 publications

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“…The project has undertaken a quality control exercise of all existing geochronometric dates (Small et al . ) and it is anticipated that these might be incorporated in future versions of the BRITICE map and database.…”

Section: Discussionmentioning

confidence: 99%

“…The ice-sheet retreat map is being used by the BRITICE-CHRONO project (2012-2018) to act as a spatial framework for collecting samples of organics, sand and boulders in a large dating programme (~800 new dates using OSL, 14 C and cosmogenic-nuclide techniques) to better constrain the timing of ice retreat, explore the controls on retreat, and to improve ice-sheet modelling (http://www.britice-chrono.group.shef.ac.uk/). The project has undertaken a quality control exercise of all existing geochronometric dates (Small et al 2017) and it is anticipated that these might be incorporated in future versions of the BRITICE map and database.…”

Section: Discussionmentioning

confidence: 99%

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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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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Self Cite

123

118

View full text Add to dashboard Cite

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“…These data were evaluated against specific criteria for the three dating methods. For all dating methods, we required multiple sample measurements to allow for some control of age consistency; single-sample age determinations were discarded (Dortch et al, 2013;Small et al, 2017). We recalculated all 10 Be exposure ages using the same approach and calculator (expage-201611) as described for the Kanas Valley samples age calculation (see 'Cosmogenic exposure dating'), for consistency.…”

Section: Outwashmentioning

confidence: 99%

“…This may lead to significant age overestimation if undetected (Duller, 2006;Fuchs and Owen, 2008). For reliable OSL ages from glacial environments we require thorough investigation of potential partial bleaching, such as small aliquot/ single grain D e distribution analysis, or signal comparison for different aliquot size or wavelength stimulation (Fuchs and Owen, 2008;Hughes et al, 2016;Small et al, 2017). In the absence of in-depth partial bleaching examination, the robustness of derived OSL ages remains uncertain and would need additional supporting chronological data to be validated.…”

Section: Outwashmentioning

confidence: 99%

Re‐evaluation of MIS 3 glaciation using cosmogenic radionuclide and single grain luminescence ages, Kanas Valley, Chinese Altai

Gribenski

Jansson

Preusser

et al. 2017

J Quaternary Science

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Previous investigations observed a period of major glacial advances in Central Asia during marine oxygen isotope stage (MIS) 3 (57–29 ka), out of phase with global ice volume records. We have re‐examined the Kanas moraine complex in the Altai Mountains of Central Asia, where an MIS 3 glaciation had been previously inferred. New and consistent cosmogenic exposure and single‐grain luminescence ages indicate that the Kanas complex was formed during MIS 2 (29–12 ka), which brings its timing in line with the global ice volume record. We also identified a lateral moraine from a more extensive ice extent that dates to late MIS 5/MIS 4. To place our results in a wider contextual framework, we review the chronologies of another 26 proposed major MIS 3 glacial advances in Central Asia. For most of these sites, we find that the chronological data do not provide an unequivocal case for MIS 3 glaciation.

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“…As a consequence, a recent review of legacy geochronological data relating to the reconstruction of the BIIS by the BRITICE‐CHRONO Consortium Project (Small et al ., in press) considered the existing chronology for the Isles of Scilly determined from 14 C, TL, OSL and TCN dating not to be reliable for constraining ice retreat. Therefore, the aim of this paper is to report new geochronological (OSL, TCN) data for the ice advance to the Isles of Scilly.…”

Section: Introductionmentioning

confidence: 97%

New age constraints for the limit of the British–Irish Ice Sheet on the Isles of Scilly

Smedley

Scourse

Small

et al. 2017

J Quaternary Science

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The southernmost terrestrial extent of the Irish Sea Ice Stream (ISIS), which drained a large proportion of the last British-Irish Ice Sheet, impinged on to the Isles of Scilly during Marine Isotope Stage 2. However, the age of this ice limit has been contested and the interpretation that this occurred during the Last Glacial Maximum (LGM) remains controversial. This study reports new ages using optically stimulated luminescence (OSL) dating of outwash sediments at Battery, Tresco (25.5 AE 1.5 ka), and terrestrial cosmogenic nuclide exposure dating of boulders overlying till on Scilly Rock (25.9 AE 1.6 ka), which confirm that the ISIS reached the Isles of Scilly during the LGM. The ages demonstrate this ice advance on to the northern Isles of Scilly occurred at $26 ka around the time of increased ice-rafted debris in the adjacent marine record from the continental margin, which coincided with Heinrich Event 2 at $24 ka. OSL dating (19.6 AE 1.5 ka) of the post-glacial Hell Bay Gravel at Battery suggests there was then an $5-ka delay between primary deposition and aeolian reworking of the glacigenic sediment, during a time when the ISIS ice front was oscillating on and around the Llŷn Peninsula, $390 km to the north.

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Devising quality assurance procedures for assessment of legacy geochronological data relating to deglaciation of the last British-Irish Ice Sheet

Cited by 57 publications

References 157 publications

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

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

Re‐evaluation of MIS 3 glaciation using cosmogenic radionuclide and single grain luminescence ages, Kanas Valley, Chinese Altai

New age constraints for the limit of the British–Irish Ice Sheet on the Isles of Scilly

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