DOI: 10.1016/j.quascirev.2015.12.015
Scopus记录号: 2-s2.0-84957881992
论文题名: Towards a morphogenetic classification of eskers: Implications for modelling ice sheet hydrology
作者: Perkins A.J. ; Brennand T.A. ; Burke M.J.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 134 起始页码: 19
结束页码: 38
语种: 英语
英文关键词: Cordilleran Ice Sheet
; Electrical resistivity tomography
; Esker
; Glacier hydrology
; GLOF
; Ground-penetrating radar
; Morphogenetic classification
Scopus关键词: Architecture
; Atmospheric pressure
; Floods
; Geological surveys
; Glaciers
; Ground penetrating radar systems
; Hydrology
; Lakes
; Radio systems
; Sedimentology
; Cordilleran ice sheet
; Electrical resistivity tomography
; Esker
; Glacier hydrology
; GLOF
; Ground Penetrating Radar
; Ice
英文摘要: Validations of paleo-ice sheet hydrological models have used esker spacing as a proxy for ice tunnel density. Changes in crest type (cross-sectional shape) along esker ridges have typically been attributed to the effect of changing subglacial topography on hydro- and ice-dynamics and hence subglacial ice-tunnel shape. These claims assume that all eskers formed in subglacial ice tunnels and that all major subglacial ice tunnels produced a remnant esker. We identify differences in geomorphic context, sinuosity, cross-sectional shape, and sedimentary architecture by analysing eskers formed at or near the margins of the last Cordilleran Ice Sheet on British Columbia's southern Fraser Plateau, and propose a morphogenetic esker classification. Three morphogenetic types and 2 subtypes of eskers are classified based on differences in geomorphic context, ridge length, sinuosity, cross-sectional shape and sedimentary architecture using geophysical techniques and sedimentary exposures; they largely record seasonal meltwater flows and glacial lake outburst floods (GLOFs) through sub-en- and supraglacial meltwater channels and ice-walled canyons. General principles extracted from these interpretations are: 1) esker ridge crest type and sinuosity strongly reflect meltwater channel type. Eskers formed in subglacial conduits are likely to be round-crested with low sinuosity (except where controlled by ice structure or modified by surging) and contain faults associated with flank collapse. Eskers formed near or at the ice surface are more likely to be sharp-crested, highly sinuous, and contain numerous faults both under ridge crest-lines and in areas of flank collapse. 2) Esker ridges containing numerous flat-crested reaches formed directly on the land-surface in ice-walled canyons (unroofed ice tunnels) or in ice tunnels at atmospheric pressure, and therefore likely record thin or dead ice. 3) Eskers containing macroforms exhibiting headward and downflow growth likely record flood-scale flows (possibly GLOFs where a lake can be inferred). These conclusions suggest that esker crest type, sinuosity and geomorphic context, when understood along with sedimentary architecture, largely reflect formational position with respect to the ice-surface. Reconstructions of ice sheet hydrology need to account for variation in esker morphology because basing hydrodynamic inferences on the presence or absence of an esker alone ignores encoded differences in water source, supply, flow magnitude and frequency, and conduit position. © 2015 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59684
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geography, Simon Fraser University, Burnaby, BC, Canada
Recommended Citation:
Perkins A.J.,Brennand T.A.,Burke M.J.. Towards a morphogenetic classification of eskers: Implications for modelling ice sheet hydrology[J]. Quaternary Science Reviews,2016-01-01,134