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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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| 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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| Ballantyne, Colin K.; Fabel, Derek; Gheorghiu, Delia; Rodes, Angel; Shanks, Richard; Xu, Sheng. |
| The St Kilda archipelago lies similar to 65 km west of the Outer Hebrides and similar to 60 km east of the Atlantic shelf break, and represents a key site for testing the assertion that during the Last Local Glacial Maximum (LLGM; c. 27 ka) the British-Irish Ice Sheet (BIIS) extended to near the shelf edge in all sectors. Two consistent cosmogenic Cl-36 exposure ages averaging (>=) 81.6 +/- 7.8 kafor perched bouldersat 290 maltitudedemonstrate that the last ice sheet failed tooverrun high ground on the largest island, Hirta. Cl-36 and Be-10 exposure ages for glacially emplaced boulders on low ground indicate deposition by small, locally nourished glaciers that last occupied a north-facing valley (Gleann Mor) at c. 30.9 +/- 3.2 ka, prior to extension of... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53143/55405.pdf |
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