DOI: 10.1016/j.quascirev.2018.05.036
Scopus记录号: 2-s2.0-85048224333
论文题名: A new approach for luminescence dating glaciofluvial deposits - High precision optical dating of cobbles
作者: Jenkins G.T.H. ; Duller G.A.T. ; Roberts H.M. ; Chiverrell R.C. ; Glasser N.F.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2018
卷: 192 起始页码: 263
结束页码: 273
语种: 英语
英文关键词: Clasts
; Europe
; Feldspar
; Glaciation
; Heterogeneous bleaching
; Optical methods
; Quaternary
Scopus关键词: Bleaching
; Cleaning
; Deposits
; Feldspar
; Glacial geology
; Sea ice
; Sediments
; Uncertainty analysis
; Water content
; Clasts
; Europe
; Glaciation
; Optical methods
; Quaternary
; Luminescence
; bleaching
; clast
; feldspar
; glaciation
; glaciofluvial deposit
; ice stream
; lithofacies
; luminescence dating
; optical method
; precision
; Quaternary
; sea ice
; uncertainty analysis
; water content
; Atlantic Ocean
; Irish Sea
; Isle of Man
; United Kingdom
英文摘要: In recent years luminescence dating has increasingly been applied to date glaciofluvial sediments, but uncertainties about the degree of bleaching of the luminescence signal at deposition make dating of such sediments challenging. Here we test a new approach for luminescence dating of glaciofluvial sediments, based on the analysis of rock cores drilled from granite cobbles, and compare the luminescence ages generated against independent age control. Luminescence measurements from rock slices in cobble-sized clasts can be used to reconstruct the extent of bleaching, thereby giving greater confidence in the ages produced. This study illustrates that another important advantage of using cobbles is that at depths of 2 mm or more below the cobble surface >90% of the total dose rate arises from the cobble itself, making the dose rate insensitive to the water content of the sediment matrix. Ordinarily, uncertainties in estimating water content during burial are one of the largest sources of uncertainty in luminescence dating methods, and hence reducing the reliance upon the dose rate could be particularly advantageous for glacial deposits, where water contents can potentially be large and highly variable. Measurements of cobbles from Orrisdale Head, Isle of Man, demonstrate that the luminescence signal was completely bleached to depths of up to 12 mm into the cobble. Sampling of orientated cobbles from lithofacies diagnostic of bar-top environments was used to maximise the chances of exposure to sunlight. The upper-faces of these orientated cobble surfaces appear to be bleached to a greater depth than the lowermost faces. Data from 45 rock slices from these cobbles were tightly clustered, yielding a mean age of 20.7 ± 0.3 ka that is in agreement with independent age control. One of the well-bleached cobbles shows evidence of two discrete exposure events, potentially recording both the advance at 26.2 ± 0.8 ka, and retreat at 20.7 ± 0.3 ka, of the Irish Sea Ice Stream. © 2018 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/112151
Appears in Collections: 气候减缓与适应
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作者单位: Department of Geography and Earth Sciences, Aberystwyth University, Ceredigion, SY23 3DB, United Kingdom; Department of Geography and Planning, University of Liverpool, Liverpool, L69 3BX, United Kingdom
Recommended Citation:
Jenkins G.T.H.,Duller G.A.T.,Roberts H.M.,et al. A new approach for luminescence dating glaciofluvial deposits - High precision optical dating of cobbles[J]. Quaternary Science Reviews,2018-01-01,192