Subglacial bedform morphology controlled by ice speed and sediment thickness

Barchyn, T.E.; Dowling, T.P.F.; Stokes, C.R.; Hugenholtz, C.G.

doi:10.1002/2016gl069558

Subglacial bedform morphology controlled by ice speed and sediment thickness

Barchyn, T.E.; Dowling, T.P.F.; Stokes, C.R.; Hugenholtz, C.G.

Authors

T.E. Barchyn

T.P.F. Dowling

Professor Chris Stokes c.r.stokes@durham.ac.uk
Professor

C.G. Hugenholtz

Abstract

Subglacial bedforms (drumlins, ribbed moraines, mega-scale glacial lineations) are enigmatic repetitive flow-parallel and flow-transverse landforms common in glaciated landscapes. Their evolution and morphology are a potentially powerful constraint for ice sheet modelling, but there is little consensus on bedform dynamics or formative mechanisms. Here we explore shallow sediment bedform dynamics via a simple model that iterates: (i) down-flow till flux, (ii) pressure gradient driven till flux, and (iii) entrainment and deposition of sediment. Under various boundary conditions, replicas of subglacial bedforms readily emerge. Bedform dynamics mirror those in subaqueous and aeolian domains. Transitions between ribbed moraines and elongate flow-parallel bedforms are associated with increasing ice speeds and declining sediment thickness. These simulations provide quantitative flux estimates and suggest that widely observed transitions in shallow sediment subglacial bedforms (e.g., ribbed moraines to drumlinoids to mega-scale glacial lineations) are manifestations of subtle variations in ice velocity and sediment thickness.

Citation

Barchyn, T., Dowling, T., Stokes, C., & Hugenholtz, C. (2016). Subglacial bedform morphology controlled by ice speed and sediment thickness. Geophysical Research Letters, 43(14), 7572-7580. https://doi.org/10.1002/2016gl069558

Journal Article Type	Article
Acceptance Date	Jul 8, 2016
Online Publication Date	Jul 30, 2016
Publication Date	Jul 30, 2016
Deposit Date	Jul 14, 2016
Publicly Available Date	Jan 30, 2017
Journal	Geophysical Research Letters
Print ISSN	0094-8276
Electronic ISSN	1944-8007
Publisher	Wiley
Peer Reviewed	Peer Reviewed
Volume	43
Issue	14
Pages	7572-7580
DOI	https://doi.org/10.1002/2016gl069558

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Copyright Statement
Thomas E. Barchyn, Thomas P. F. Dowling, Chris R. Stokes, Chris H. Hugenholtz (2016), Subglacial bedform morphology controlled by ice speed and sediment thickness, Geophysical research letters, 43(14): 7572-7580, 10.1002/2016GL069558 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.