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| Small, David; Parrish, Randall R.; Austin, William E. N.; Cawood, Peter A.; Rinterknecht, Vincent. |
| Understanding the provenance of ice-rafted debris (IRD) provides a means to link the behavior of individual ice sheets to proxy records of climate change. Here we present a new approach to determining IRD provenance using U-Pb geochronology of detrital minerals rutile and zircon. We characterize potential source regions from Scotland using detrital rutile from modern fluvial systems, and demonstrate that their unimodal rutile U-Pb ages reflect the timing of the last amphibolite facies metamorphism of the source rocks, imparting a distinctive source signature. Contrasts between these spectra and the bimodal IRD (ca. 470 Ma and ca. 1800-2000 Ma) rutile age signatures rule out Scotland as the sole source and suggest a Laurentian contribution; IRD zircon ages... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00181/29197/27590.pdf |
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| Callard, S. Louise; Cofaigh, Colm O.; Benetti, Sara; Chiverrell, Richard C.; Van Landeghem, Katrien J. J.; Saher, Margot H.; Gales, Jenny A.; Small, David; Clark, Chris D.; Stephen, J. Livingstone; Fabel, Derek; Moreton, Steven G.. |
| During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BITS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we... |
| Tipo: Text |
Palavras-chave: British-Irish Ice Sheet; Glacimarine; Last glacial maximum; Radiocarbon dating; Ice-sheet retreat; Grounding-zone wedges. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00504/61588/65891.pdf |
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| Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourles, Didier L.; Hibbert, Fiona D.. |
| Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new 36Cl cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5–17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a... |
| Tipo: Text |
Palavras-chave: Deglaciation; Scotland; Cosmogenic exposure ages; Chlorine-36. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00349/46010/83047.pdf |
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| Small, David; Benetti, Sara; Dove, Dayton; Ballantyne, Colin K.; Fabel, Derek; Clark, Chris D.; Gheorghiu, Delia M.; Newall, Jennifer; Xu, Sheng. |
| Understanding how marine-based ice streams operated during episodes of deglaciation requires geochronological data that constrain both timing of deglaciation and changes in their flow behaviour, such as that from unconstrained ice streaming to topographically restricted flow. We present seventeen new Be-10 exposure ages from glacial boulders and bedrock at sites in western Scotland within the area drained by the Hebrides Ice Stream, a marine-based ice stream that drained a large proportion of the former British-Irish Ice Sheet. Exposure ages from Tiree constrain deglaciation of a topographic high within the central zone of the ice stream, from which convergent flowsets were produced during ice streaming. These ages thus constrain thinning of the Hebrides... |
| Tipo: Text |
Palavras-chave: Exposure dating; Marine ice stream; British-Irish ice sheet; Deglaciation. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53148/55337.pdf |
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| Small, David. |
| It is now accepted that the last British-Irish Ice Sheet (BIIS) was highly dynamic and drained by numerous fast flowing ice streams. This dynamic nature combined with its maritime location made the BIIS sensitive to the rapid climate change that characterised the Last Glacial Interglacial Transition. Gaining an understanding of the behaviour of the BIIS at this time is important to explore the nature of forcing between ice sheets and climate. This thesis presents new chronological data relating to the deglaciation of the northwest sector of the BIIS (NW-BIIS) from onshore dating of moraines using cosmogenic exposure dating. This improved chronological framework is supported by offshore data in the form of a newly constructed Ice Rafted Detritus (IRD)... |
| Tipo: Text |
Palavras-chave: British-Irish Ice Sheet; Deglaciation; Cosmogenic; Ice rafted detritus; Provenance; Environmental change. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00499/61039/64446.pdf |
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| Small, David; Clark, Chris D.; Chiverrell, Richard C.; Smedley, Rachel K.; Bateman, Mark D.; Duller, Geoff A. T.; Ely, Jeremy C.; Fabel, Derek; Medialdea, Alicia; Moreton, Steven G.. |
| This contribution documents the process of assessing the quality of data within a compilation of legacy geochronological data relating to the last British-Irish Ice Sheet, a task undertaken as part of a larger community-based project (BRITICE-CHRONO) that aims to improve understanding of the ice sheet's deglacial evolution. As accurate reconstructions depend on the quality of the available data, some form of assessment is needed of the reliability and suitability of each given age(s) in our dataset. We outline the background considerations that informed the quality assurance procedures devised given our specific research question. We describe criteria that have been used to make an objective assessment of the likelihood that an age is influenced by the... |
| Tipo: Text |
Palavras-chave: British-Irish Ice Sheet; Deglaciation; Geochronology; Data compilations; Quality assurance; Bayesian. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00504/61598/65865.pdf |
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| Ballantyne, Colin K.; Small, David. |
| The last Scottish Ice Sheet (SIS) expanded from a pre-existing ice cap after ∼35 ka. Highland ice dominated, with subsequent build-up of a Southern Uplands ice mass. The Outer Hebrides, Skye, Mull, the Cairngorms and Shetland supported persistent independent ice centres. Expansion was accompanied by ice-divide migration and switching flow directions. Ice nourished in Scotland reached the Atlantic Shelf break in some sectors but only mid-shelf in others, was confluent with the Fennoscandian Ice Sheet (FIS) in the North Sea Basin, extended into northern England, and fed the Irish Sea Ice Stream and a lobe that reached East Anglia. The timing of maximum extent was diachronous, from ∼30–27 ka on the Atlantic Shelf to ∼22–21 ka in Yorkshire. The SIS buried all... |
| Tipo: Text |
Palavras-chave: British-Irish Ice Sheet; Deglaciation; Dimlington Stade; Flowsets; Ice streams; Late Devensian; Lithostratigraphy; Radiocarbon dating; Readvances; Terrestrial cosmogenic nuclide dating. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00505/61627/65539.pdf |
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| Small, David; Austin, William; Rinterknecht, Vincent. |
| A sediment core from the north-east North Atlantic contains high-resolution co-registered foraminiferal O-18 and ice-rafted detritus (IRD) records for the last deglaciation. These reveal a distinct ice-rafting event that occurred at the time of Greenland Interstade 1d (GI-1d), a feature also seen in other high-resolution cores from the North Atlantic. The occurrence of a geographically widespread peak in IRD at ice distal sites at a time when increased freshwater flux to the surface ocean is inferred to have caused rapid cooling suggests a mechanistic link between the processes, analogous to the Younger Dryas (GS-1) cooling episode. The general absence of IRD at southern locations at other times during GI-1 when the flux of icebergs from surviving ice... |
| Tipo: Text |
Palavras-chave: Deglaciation; Hydrography; Ice-rafted detritus; North Atlantic; Sea surface temperature. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00291/40180/39238.pdf |
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