DOI: 10.5194/tc-10-553-2016
Scopus记录号: 2-s2.0-84960855966
论文题名: A comprehensive interpretation of the NEEM basal ice build-up using a multi-parametric approach
作者: Goossens T ; , Sapart C ; J ; , Dahl-Jensen D ; , Popp T ; , Amri S ; E ; , Tison J ; -L
刊名: Cryosphere
ISSN: 19940416
出版年: 2016
卷: 10, 期: 2 起始页码: 553
结束页码: 567
语种: 英语
英文关键词: basal ice
; climate signal
; GRIP
; ice core
; ice sheet
; reconstruction
; stable isotope
; subglacial environment
英文摘要: Basal ice is a common expression to describe bottom ice layers of glaciers, ice caps and ice sheets in which the ice is primarily conditioned by processes operating at the bed. It is chemically and/or physically distinct from the ice above and can be characterized by a component of basally derived sediments. The study of basal ice properties provides a rare opportunity to improve our understanding of subglacial environments and processes and to refine ice sheet behaviour modelling. Here, we present and discuss the results of water stable isotopes (δ18O and δD), ice fabrics, debris weight/size distribution and gas content of the basal part of the NEEM (North Greenland Eemian Ice Drilling Project) ice core. Below a depth of 2533.85 m, almost 10 m of basal debris-rich material was retrieved from the borehole, and regular occurrence of frozen sediments with only interstitial ice lenses in the bottom 5 m suggest that the ice-bedrock interface was reached. The sequence is composed of an alternation of three visually contrasting types of ice: clear ice with specks (very small amounts) of particulate inclusions, stratified debris-rich layers and ice containing dispersed debris. The use of water stable isotope signatures (δ18O and δD), together with other parameters, allows discrimination between the different types of ice and to unravel the processes involved in their formation and transformation. The basal debris-rich material presents δ18O values [−39.9 ‰; −34.4 ‰] within the range of the above last 300 m of unaltered meteoric ice [−44.9 ‰; −30.6 ‰] spanning a glacial-interglacial range of values. This rules out the hypothesis of a basal ice layer originating from pre-ice sheet ice overridden by the growing ice sheet, as previously suggested e.g. in the case of GRIP (Greenland Ice Core Project). We show that clear basal ice with specks corresponds to altered meteoric glacial ice where some of the climatic signal could have been preserved. However, the stratified debris-rich layers and the ice containing dispersed debris layers respectively express an "open" or "closed" system melting/refreezing signature, somewhat blurred by mixing processes in the upper part of the sequence. Climatic reconstruction is therefore prohibited from these ice types. We propose a first interpretative framework for the build-up of the NEEM basal ice sequence, based on the origin of the various ice types. © Author(s) 2016. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75174
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium; Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands; Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Recommended Citation:
Goossens T,, Sapart C,J,et al. A comprehensive interpretation of the NEEM basal ice build-up using a multi-parametric approach[J]. Cryosphere,2016-01-01,10(2)