Size, shape and spatial arrangement of mega-scale glacial lineations from a large and diverse dataset

Matteo Spagnolo*, Chris D. Clark, Jeremy C. Ely, Chris R. Stokes, John B. Anderson, Karin Andreassen, Alastair G. C. Graham, Edward C. King

*Corresponding author for this work

Research output: Contribution to journalArticle

105 Citations (Scopus)
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Abstract

Mega-scale glacial lineations (MSGLs) are a characteristic landform on ice stream beds. Solving the puzzle of their formation is key to understanding how ice interacts with its bed and how this, in turn, influences the dynamics of ice streams. However, a comprehensive and detailed characterization of this landform's size, shape and spatial arrangement, which might serve to test and refine formational theories, is largely lacking. This paper presents a detailed morphometric analysis and comparison of 4043 MSGLs from eight palaeo-ice stream settings: three offshore (Norway and Antarctica), four onshore (Canada), and one from under a modern ice stream in West Antarctica. The length of MSGLs is lower than previously suggested (mode 1000-2000 m; median 2892 m), and they initiate and terminate at various locations on an ice stream bed. Their spatial arrangement reveals a pattern that is characterized by an exceptional parallel conformity (80% of all mapped MSGLs have an azimuth within 5 degrees from the mean values), and a fairly constant lateral spacing (mode 200-300 m; median 330 m), which we interpret as an indication that MSGLs are a spatially self-organized phenomenon. Results show that size, shape and spatial arrangement of MSGLs are consistent both within and also generally between different ice stream beds. We suggest this results from a common mechanism of formation, which is largely insensitive to local factors. Although the elongation of MSGLs (mode 6-8; median 12.2) is typically higher than features described as drumlins, these values and those of their width (mode 100-200 m; median 268 m) overlap, which suggests the two landforms are part of a morphological continuum and may share a similar origin. We compare their morphometry with explicit predictions made by the groove-ploughing and rilling instability theories of MSGL formation. Although the latter was most compatible, neither is fully supported by observations. (C) 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.

Original languageEnglish
Pages (from-to)1432-1448
Number of pages17
JournalEarth Surface Processes and Landforms
Volume39
Issue number11
Early online date24 Feb 2014
DOIs
Publication statusPublished - 15 Sep 2014

Keywords

  • MSGL
  • glacial bedform
  • ice stream
  • morphometry
  • Antarctic Ice-Sheet
  • grounding-line retreat
  • 3-dimensional seismic data
  • sea-floor evidence
  • trough mouth fans
  • Pine Island Bay
  • Continental-Shelf
  • Barents Sea
  • Arctic-Ocean
  • Ross Sea

Cite this

Spagnolo, M., Clark, C. D., Ely, J. C., Stokes, C. R., Anderson, J. B., Andreassen, K., Graham, A. G. C., & King, E. C. (2014). Size, shape and spatial arrangement of mega-scale glacial lineations from a large and diverse dataset. Earth Surface Processes and Landforms, 39(11), 1432-1448. https://doi.org/10.1002/esp.3532