Concentrated, ‘pulsed’ axial glacier flow: structural glaciological evidence from Kvíárjökull in SE Iceland

Phillips, Emrys; Everest, Jez; Evans, David J. A.; Finlayson, Andrew; Ewertowski, Marek; Guild, Ailsa; Jones, Lee

doi:10.1002/esp.4145

Cited by 20 publications

(82 citation statements)

References 74 publications

(106 reference statements)

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“…Phillips et al . () propose that fracture (i.e. crevasse) patterns at Kvíárjökull (Figure ), a temperate glacier in southeast Iceland, indicate that flow since c .…”

Section: Introductionsupporting

confidence: 57%

“…(b) Domains mapped by Phillips et al . (), superimposed onto an August 2009 aerial image. Annotations highlight an ‘axial flow’ corridor of more elongate lobes, and deflection of flow toward the true‐left by dextral shear near the terminus, as proposed by Phillips et al .…”

Section: Introductionmentioning

confidence: 97%

“…Annotations highlight an ‘axial flow’ corridor of more elongate lobes, and deflection of flow toward the true‐left by dextral shear near the terminus, as proposed by Phillips et al . (). (c) Annotated aerial image showing a heavily crevassed ice surface, and highlighting dark ogive banding and prominent transverse englacial foliation.…”

Section: Introductionmentioning

confidence: 97%

“…We set out to test the pulsed axial flow hypothesis of Phillips et al . () because crevasse patterns are more commonly interpreted to reflect local tensile stresses caused by undulations at the glacier bed (see Discussion). In addition, Swift et al .…”

Section: Introductionmentioning

confidence: 99%

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Going against the flow: Testing the hypothesis of pulsed axial glacier flow

Swift

Jones

2018

Earth Surf Processes Landf

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Hypothesised lobe‐like flow of a temperate glacier in southeast Iceland, proposed from an analysis of ice surface crevassing patterns, is appraised from both empirical and theoretical perspectives. The hypothesis comprises the migration of individual lobes (or ‘pulses’) of ice through the glacier body, with central lobes migrating more rapidly along a narrow, central, ‘axial flow corridor’. Our alternative hypothesis is that crevasse patterns at this glacier reflect simple surface ice responses to stresses caused by flow over uneven bed topography. To substantiate our rejection of the lobe‐like, pulsed axial flow hypothesis, we provide: (a) evidence for a prominent transverse foliation that exhibits no evidence of shear of the required magnitude to support the hypothesis; and (b) an analysis of ice surface displacement, obtained by feature tracking, that shows a uniform flow field throughout the glacier tongue. We argue that caution needs to be exercised when interpreting glacier flow solely from crevasse patterns and observations of minor displacements along near‐surface fractures and other features. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

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“…Phillips et al . () propose that fracture (i.e. crevasse) patterns at Kvíárjökull (Figure ), a temperate glacier in southeast Iceland, indicate that flow since c .…”

Section: Introductionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Going against the flow: Testing the hypothesis of pulsed axial glacier flow

Swift

Jones

2018

Earth Surf Processes Landf

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“…A number of studies have conducted detailed structural surveys of polar and Alpine glaciers (e.g. Goodsell, Hambrey, & Glasser, 2002;Goodsell, Hambrey, Glasser, Nienow, & Mair, 2005;Hambrey & Lawson, 2000;Jennings, Hambrey, Glasser, James, & Hubbard, 2016), but a few have assessed the temporal evolution of glacier structures in response to evolving stress and strain regimes (Glasser & Scambos, 2008;Hambrey et al, 2005;Phillips et al, 2017). This study aims to map brittle and ductile structures originated from the glacier dynamics, by means of the analysis of high-resolution orthophotos, and to describe structural controls of glacier disintegration for a rapidly downwasting Alpine glacier by investigating structure evolution.…”

Section: Introductionmentioning

confidence: 99%

Recent structural evolution of Forni Glacier tongue (Ortles-Cevedale Group, Central Italian Alps)

et al. 2017

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Structural glaciology yields important details about the evolution of glacier dynamics in response to climate change. The maps provided here document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014. Through the remote sensing-based analysis of structures, we found evidence of brittle fractures such as crevasses, faults and ring faults, and ductile structures such as ogives at the base of the icefall in the eastern glacier tongue. Although each of the three glacier tongues have evolved differently, a reduction in flow-related dynamics and an increase in the number of collapse structures occurred over the study period. Analysis of the glacier structural evolution based on the numbers and the locations of different structures, suggest a slowdown of glacier flow on the eastern tongue. The recent evolution of the glacier also suggests that the occurrence of a disintegration scenario is likely to worsen over the next decades.ARTICLE HISTORY

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Subglacial drumlins and englacial fractures at the surge‐type glacier, Múlajökull, Iceland

Finlayson

Phillips

Benediktsson

et al. 2018

Earth Surf Processes Landf

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The interaction between drumlins and overriding glacier ice is not well studied, largely due to the difficulty of identifying and accessing suitable active subglacial environments. The surge‐type glacier Múlajökull, in central Iceland, overlies a known field of actively forming drumlins and therefore provides a rare opportunity to investigate the englacial structures that have developed in association with ice flow over the subglacial drumlins. In this study detailed ground‐penetrating radar surveys are combined with field observations to identify clear sets of up‐glacier and down‐glacier dipping fractures at Múlajökull's margin. These are interpreted as conjugate shear planes or P‐ and R‐type Reidel shears that developed and filled with saturated sediment derived from the glacier bed, during a previous surge. The fracture sets exhibit focused spatial distributions that are influenced by the subglacial topography. In particular, down‐glacier dipping fractures are strongly focused over drumlin stoss slopes. These fractures, although well developed at depth, were mostly unable to transmit basal water and sediment up to the glacier surface during the surge cycle. In contrast, up‐glacier dipping fractures formed over drumlin lee sides and in more gently sloping swales, and more frequently connected to the glacier surface, providing a pathway for the evacuation of basal water and water‐saturated sediment. The study suggests that the subglacial drumlins under Múlajökull's margin have influenced the nature and distribution of englacial fractures, which could potentially contribute to spatial variations in basal water pressure during a surge. BGS © UKRI 2018

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Concentrated, ‘pulsed’ axial glacier flow: structural glaciological evidence from Kvíárjökull in SE Iceland

Cited by 20 publications

References 74 publications

Going against the flow: Testing the hypothesis of pulsed axial glacier flow

Going against the flow: Testing the hypothesis of pulsed axial glacier flow

Recent structural evolution of Forni Glacier tongue (Ortles-Cevedale Group, Central Italian Alps)

Subglacial drumlins and englacial fractures at the surge‐type glacier, Múlajökull, Iceland

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