A meltwater origin for Antarctic shelf bedforms with special attention to megalineations

Shaw, John; Pugin, A.; Young, Robert R.

doi:10.1016/j.geomorph.2008.04.005

Cited by 46 publications

(69 citation statements)

References 94 publications

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“…However, offshore till provenance analyses indicate that the EAIS and WAIS had roughly equal contributions to ice draining into the Ross Sea (Anderson et al, 1984;Licht et al, 2005;Farmer et al, 2006). Significant drainage of the EAIS into the WRS is also supported by interpretations from sea floor glacial geomorphology (Shipp et al, 1999;Mosola and Anderson, 2006;Greenwood et al, 2012;Anderson et al, 2014), exposure age dating in the Transantarctic Mountains (e.g. Jones et al, 2015), and numerical ice-sheet models (e.g.…”

Section: Study Areamentioning

confidence: 84%

“…Results from marine geological research, including integrated seismic stratigraphy, geomorphology, and sediment core analyses, indicate that both the EAIS and WAIS advanced across the continental shelf during the LGM Shipp et al, 1999;Mosola and Anderson, 2006;Anderson et al, 2014). The relative contributions of the EAIS and WAIS to LGM ice flow and subsequent palaeodrainage and retreat behaviour in the Ross Sea remain controversial.…”

Section: Study Areamentioning

confidence: 99%

“…While the actual formation process for MSGLs is still debated (e.g. Tulaczyk et al, 2001;Shaw et al, 2008;Ó Cofaigh et al, 2008;Fowler, 2010), they are interpreted as having formed under streaming ice due to their association with modern ice streams (King et al, 2009) and their occurrence within palaeo-glacial troughs (Anderson, 1999;Livingstone et al, 2012). The streamlined nature of MSGLs makes them excellent indicators of ice-flow direction (Clark, 1993;Stokes and Clark, 1999;Shipp et al, 1999;Ó Cofaigh et al, 2002;Dowdeswell et al, 2004;Spagnolo et al, 2014).…”

Section: Subglacial Featuresmentioning

confidence: 99%

“…The streamlined nature of MSGLs makes them excellent indicators of ice-flow direction (Clark, 1993;Stokes and Clark, 1999;Shipp et al, 1999;Ó Cofaigh et al, 2002;Dowdeswell et al, 2004;Spagnolo et al, 2014). Previous studies have shown that MSGLs are associated with a massive seismic facies interpreted as the deformation till layer deposited above the latest glacial unconformity (Shipp et al, 1999;Ó Cofaigh et al, 2002Ó Cofaigh et al, , 2005Heroy and Anderson, 2005). Most MSGLs in the Ross Sea have amplitudes of 1-9 m and lengths of about 1-10 km.…”

Section: Subglacial Featuresmentioning

confidence: 99%

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Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

et al. 2016

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Abstract. Studying the history of ice-sheet behaviour in the Ross Sea, Antarctica's largest drainage basin can improve our understanding of patterns and controls on marinebased ice-sheet dynamics and provide constraints for numerical ice-sheet models. Newly collected high-resolution multibeam bathymetry data, combined with two decades of legacy multibeam and seismic data, are used to map glacial landforms and reconstruct palaeo ice-sheet drainage.During the Last Glacial Maximum, grounded ice reached the continental shelf edge in the eastern but not western Ross Sea. Recessional geomorphic features in the western Ross Sea indicate virtually continuous back-stepping of the icesheet grounding line. In the eastern Ross Sea, well-preserved linear features and a lack of small-scale recessional landforms signify rapid lift-off of grounded ice from the bed. Physiography exerted a first-order control on regional ice behaviour, while sea floor geology played an important subsidiary role.Previously published deglacial scenarios for Ross Sea are based on low-spatial-resolution marine data or terrestrial observations; however, this study uses high-resolution basinwide geomorphology to constrain grounding-line retreat on the continental shelf. Our analysis of retreat patterns suggests that (1) retreat from the western Ross Sea was complex due to strong physiographic controls on ice-sheet drainage; (2) retreat was asynchronous across the Ross Sea and between troughs; (3) the eastern Ross Sea largely deglaciated prior to the western Ross Sea following the formation of a large grounding-line embayment over Whales Deep; and (4) our glacial geomorphic reconstruction converges with recent numerical models that call for significant and complex East Antarctic ice sheet and West Antarctic ice sheet contributions to the ice flow in the Ross Sea.

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Section: Study Areamentioning

confidence: 84%

Section: Study Areamentioning

confidence: 99%

Section: Subglacial Featuresmentioning

confidence: 99%

Section: Subglacial Featuresmentioning

confidence: 99%

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Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

et al. 2016

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“…This hypothesis has recently been validated by King et al (2009), who have found MSGLs under the Rutford ice stream in Antarctica. While it is generally agreed that MSGLs are formed through the action of ice (although see Shaw et al (2008) and the reply by Ó Cofaigh et al (2010)), it is as yet unclear how they do so. The question is of practical, as well as scientific interest, since it has a bearing on the drag that the bed offers the ice, and hence on how rapidly the ice streams discharge.…”

Section: Introductionmentioning

confidence: 99%

The formation of subglacial streams and mega-scale glacial lineations

Fowler

2010

Proc. R. Soc. A.

103

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The instability theory of drumlin formation has been very successful in predicting the existence of ribbed moraine, as well as its amplitude and wavelength. However, the theory as it stands has not yet been shown to have the capability of predicting the existence of three-dimensional bedforms-drumlins-or their more extreme cousins, mega-scale glacial lineations. We extend the instability theory to include a dynamic description of the local subglacial drainage system, and in particular, we show that a uniform water-film flow between ice and deformable subglacial till is unstable, and that as a consequence, lineations will form. Predictions of the transverse wavelengths are consistent with observations.

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The periodic topography of ice stream beds: Insights from the Fourier spectra of mega‐scale glacial lineations

et al. 2017

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Ice stream bed topography contains key evidence for the ways ice streams interact with, and are potentially controlled by, their beds. Here we present the first application of two‐dimensional Fourier analysis to 22 marine and terrestrial topographies from 5 regions in Antarctica and Canada, with and without mega‐scale glacial lineations (MSGLs). We find that the topography of MSGL‐rich ice stream sedimentary beds is characterized by multiple, periodic wavelengths between 300 and 1200 m and amplitudes from decimeters to a few meters. This periodic topography is consistent with the idea that instability is a key element to the formation of MSGL bedforms. Dominant wavelengths vary among locations and, on one paleo ice stream bed, increase along the direction of ice flow by 1.7 ± 0.52% km−1. We suggest that these changes are likely to reflect pattern evolution via downstream wavelength coarsening, even under potentially steady ice stream geometry and flow conditions. The amplitude of MSGLs is smaller than that of other fluvial and glacial topographies but within the same order of magnitude. However, MSGLs are a striking component of ice stream beds because the topographic amplitude of features not aligned with ice flow is reduced by an order of magnitude relative to those oriented with the flow direction. This study represents the first attempt to automatically derive the spectral signatures of MSGLs. It highlights the plausibility of identifying these landform assemblages using automated techniques and provides a benchmark for numerical models of ice stream flow and subglacial landscape evolution.

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A meltwater origin for Antarctic shelf bedforms with special attention to megalineations

Cited by 46 publications

References 94 publications

Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

The formation of subglacial streams and mega-scale glacial lineations

The periodic topography of ice stream beds: Insights from the Fourier spectra of mega‐scale glacial lineations

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