globalchange  > 气候减缓与适应
DOI: 10.1002/2017JF004297
Scopus记录号: 2-s2.0-85042441998
论文题名:
Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland
作者: Hofstede C.; Christoffersen P.; Hubbard B.; Doyle S.H.; Young T.J.; Diez A.; Eisen O.; Hubbard A.
刊名: Journal of Geophysical Research: Earth Surface
ISSN: 21699003
出版年: 2018
卷: 123, 期:2
起始页码: 349
结束页码: 362
语种: 英语
英文关键词: anisotropy ; deformation ; patches ; seismic ; sliding ; subglacial
Scopus关键词: anisotropy ; deformation ; glacial deposit ; glacier dynamics ; ice ; seismic data ; seismic reflection ; subglacial deposit ; Arctic ; Greenland ; Store Glacier
英文摘要: Outlet glaciers of the Greenland Ice Sheet transport ice from the interior to the ocean and contribute directly to sea level rise because discharge and ablation often exceed the accumulation. To develop a better understanding of these fast-flowing glaciers, we investigate the basal conditions of Store Glacier, a large outlet glacier flowing into Uummannaq Fjord in west Greenland. We use two crossing seismic profiles acquired near the centerline, 30 km upstream of the calving front, to interpret the physical nature of the ice and bed. We identify one notably englacial and two notably subglacial seismic reflections on both profiles. The englacial reflection represents a change in crystal orientation fabric, interpreted to be the Holocene-Wisconsin transition. From Amplitude-Versus-Angle (AVA) analysis we infer that the deepest ∼80 m of ice of the parallel-flow profile below this reflection is anisotropic with an enhancement of simple shear of ∼2. The ice is underlain by ∼45 m of unconsolidated sediments, below which there is a strong reflection caused by the transition to consolidated sediments. In the across-flow profile subglacial properties vary over small scale and the polarity of the ice-bed reflection switches from positive to negative. We interpret these as patches of different basal slipperiness associated with variable amounts of water. Our results illustrate variability in basal properties, and hence ice-bed coupling, at a spatial scale of ∼100 m, highlighting the need for direct observations of the bed to improve the basal boundary conditions in ice-dynamic models. ©2018. The Authors.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114541
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作者单位: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany; Scott Polar Research Institute, Cambridge University, Cambridge, United Kingdom; Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom; British Antarctic Survey, National Environmental Research Council, Cambridge, United Kingdom; Norwegian Polar Institute, Framsenteret, Tromsø, Norway; Faculty of Geosciences, University of Bremen, Bremen, Germany; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geology, Arctic University of Norway, Tromsø, Norway

Recommended Citation:
Hofstede C.,Christoffersen P.,Hubbard B.,et al. Physical Conditions of Fast Glacier Flow: 2. Variable Extent of Anisotropic Ice and Soft Basal Sediment From Seismic Reflection Data Acquired on Store Glacier, West Greenland[J]. Journal of Geophysical Research: Earth Surface,2018-01-01,123(2)
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