DOI: 10.1016/j.quascirev.2017.04.021
论文题名: Cosmogenic exposure age constraints on deglaciation and flow behaviour of a marine-based ice stream in western Scotland, 21–16 ka
作者: Small D. ; Benetti S. ; Dove D. ; Ballantyne C.K. ; Fabel D. ; Clark C.D. ; Gheorghiu D.M. ; Newall J. ; Xu S.
刊名: Quaternary Science Reviews
出版年: 2017
卷: 167 起始页码: 30
结束页码: 46
语种: 英语
英文关键词: British-Irish ice sheet
; Deglaciation
; Exposure dating
; Marine ice stream
Scopus关键词: Geochronology
; Glacial geology
; Glaciers
; Snow
; British-Irish ice sheet
; Cosmogenic exposure
; Deglaciations
; Exposure dating
; Flow behaviours
; Ice streams
; Numerical reconstruction
; Restricted flows
; Ice
英文摘要: 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 10Be 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 Ice Stream, which, on the basis of supporting information, we infer to represent cessation of ice streaming at 20.6 ± 1.2 ka, 3–4 ka earlier than previously inferred. A period of more topographically restricted flow produced flow indicators superimposed on those relating to full ice stream conditions, and exposure ages from up-stream of these constrain deglaciation to 17.5 ± 1.0 ka. Complete deglaciation of the marine sector of the Hebrides Ice Stream occurred by 17–16 ka at which time the ice margin was located near the present coastline. Exposure ages from the southernmost Outer Hebrides (Mingulay and Barra) indicate deglaciation at 18.9 ± 1.0 and 17.1 ± 1.0 ka respectively, demonstrating that an independent ice cap persisted on the southern Outer Hebrides for 3–4 ka after initial ice stream deglaciation. This suggests that deglaciation of the Hebrides Ice Stream was focused along major submarine troughs. Collectively, our data constrain initial deglaciation and changes in flow regime of the Hebrides Ice Stream, final deglaciation of its marine sector, and deglaciation of the southern portion of the independent Outer Hebrides Ice Cap, providing chronological constraints on future numerical reconstructions of this key sector of the former British-Irish Ice Sheet. © 2017 The Authors 资助项目: Small, D.
; Department of Geographical and Earth Sciences, University of GlasgowUnited Kingdom
; 电子邮件: David.Small@glasgow.ac.uk
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59204
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geographical and Earth Sciences, University of Glasgow, Glasgow, United Kingdom; School of Environmental Sciences, University of Ulster, Coleraine, United Kingdom; British Geological Survey, The Lyell Centre, Edinburgh, United Kingdom; School of Geography and Sustainable Development, University of St Andrews, St Andrews, United Kingdom; SUERC AMS Laboratory, Scottish Universities Environmental Research Centre, East Kilbride, United Kingdom; Department of Geography, University of Sheffield, Sheffield, United Kingdom; NERC Cosmogenic Isotope Analysis Facility, SUERC, East Kilbride, United Kingdom
Recommended Citation:
Small D.,Benetti S.,Dove D.,et al. Cosmogenic exposure age constraints on deglaciation and flow behaviour of a marine-based ice stream in western Scotland, 21–16 ka[J]. Quaternary Science Reviews,2017-01-01,167