DOI: 10.1016/j.quascirev.2018.06.009
Scopus记录号: 2-s2.0-85049355825
论文题名: Progressive ductile shearing during till accretion within the deforming bed of a palaeo-ice stream
作者: Phillips E. ; Spagnolo M. ; Pilmer A.C.J. ; Rea B.R. ; Piotrowski J.A. ; Ely J.C. ; Carr S.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2018
卷: 193 起始页码: 1
结束页码: 23
语种: 英语
英文关键词: Ductile shearing
; Foliation development
; Glacier bed deformation
; Micromorphology
; Palaeo-ice stream
Scopus关键词: Deformation
; Flow patterns
; Sea ice
; Shear flow
; Shearing
; Tectonics
; Bed deformation
; Ductile shearing
; Foliation development
; Ice streams
; Micromorphologies
; Shearing machines
; accretion
; deformation
; ductility
; glacier flow
; ice flow
; ice stream
; micromorphology
; microstructure
; paleosurface
; Scandinavian Ice Sheet
; shear strength
; shear zone
; Weichselian
; Atlantic Ocean
; Baltic Sea
; Poland [Central Europe]
; Wielkopolska
英文摘要: This paper presents the results of a detailed microstructural study of a thick till formed beneath the Weichselian (Devensian) Odra palaeo-ice stream, west of Środa Wielkopolska, Poland. This SE-flowing ice stream was one of a number of corridors of faster flowing ice which drained the Scandinavian Ice Sheet in the Baltic region. Macroscopically, the massive, laterally extensive till which formed the bed of this ice stream lacks any obvious evidence of glaciotectonism (thrusting, folding). However, microscale analysis reveals that bed deformation was dominated by foliation development, recording progressive ductile shearing within a subhorizontal subglacial shear zone. Five successive generations of clast microfabric (S1 to S5) have been identified defining a set of up-ice and down-ice dipping Riedel shears, as well as a subhorizontal shear foliation coplanar to the ice-bed interface. Cross-cutting relationships between the shear fabrics record temporal changes in the style of deformation during this progressive shear event. Kinematic indicators (S-C and ECC-type fabrics) within the till indicate a consistent SE-directed shear sense, in agreement with the regional ice flow pattern. A model of bed deformation involving incremental progressive simple shear during till accretion is proposed. The relative age of this deformation was diachronous becoming progressively younger upwards, compatible with subglacial shearing having accompanied till accretion at the top of the deforming bed. Variation in the relative intensity of the microfabrics records changes in the magnitude of the cumulative strain imposed on the till and the degree of coupling between the ice and underlying bed during fast ice flow. © 2018 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/112122
Appears in Collections: 气候减缓与适应
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作者单位: British Geological Survey, The Lyell Centre, Research Avenue South, Edinburgh, EH14 4AP, United Kingdom; Department of Geography and the Environment, School of Geosciences, University of Aberdeen, Aberdeen, AB24 3UF, United Kingdom; Department of Geoscience, Aarhus University, Denmark; Department of Geography, University of Sheffield, Sheffield, S10 2TN, United Kingdom; School of Geography, Queen Mary, University of London, Mile End Road, London, E1 4NS, United Kingdom
Recommended Citation:
Phillips E.,Spagnolo M.,Pilmer A.C.J.,et al. Progressive ductile shearing during till accretion within the deforming bed of a palaeo-ice stream[J]. Quaternary Science Reviews,2018-01-01,193