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Subglacial bed form morphology controlled by ice speed and sediment thickness

Barchyn, Thomas E.; Dowling, Thomas P F LU ; Stokes, Chris R. and Hugenholtz, Chris H. (2016) In Geophysical Research Letters 43(14). p.7572-7580
Abstract

Subglacial bed forms (drumlins, ribbed moraines, and megascale 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 modeling, but there is little consensus on bed form dynamics or formative mechanisms. Here we explore shallow sediment bed form 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 bed forms readily emerge. Bed form dynamics mirror those in subaqueous and aeolian domains. Transitions between ribbed moraines and... (More)

Subglacial bed forms (drumlins, ribbed moraines, and megascale 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 modeling, but there is little consensus on bed form dynamics or formative mechanisms. Here we explore shallow sediment bed form 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 bed forms readily emerge. Bed form dynamics mirror those in subaqueous and aeolian domains. Transitions between ribbed moraines and elongate flow-parallel bed forms 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 bed forms (e.g., ribbed moraines to drumlinoids to megascale glacial lineations) are manifestations of subtle variations in ice velocity and sediment thickness.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
drumlins, instability, megascale glacial lineations, paleolandscapes, ribbed moraines, rogen moraines
in
Geophysical Research Letters
volume
43
issue
14
pages
9 pages
publisher
American Geophysical Union
external identifiers
  • scopus:84979782482
  • wos:000383290200035
ISSN
0094-8276
DOI
10.1002/2016GL069558
language
English
LU publication?
yes
id
d1a30159-4c27-4b87-9fe6-06288ea261d7
date added to LUP
2016-12-19 14:03:14
date last changed
2017-10-01 05:27:49
@article{d1a30159-4c27-4b87-9fe6-06288ea261d7,
  abstract     = {<p>Subglacial bed forms (drumlins, ribbed moraines, and megascale 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 modeling, but there is little consensus on bed form dynamics or formative mechanisms. Here we explore shallow sediment bed form 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 bed forms readily emerge. Bed form dynamics mirror those in subaqueous and aeolian domains. Transitions between ribbed moraines and elongate flow-parallel bed forms 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 bed forms (e.g., ribbed moraines to drumlinoids to megascale glacial lineations) are manifestations of subtle variations in ice velocity and sediment thickness.</p>},
  author       = {Barchyn, Thomas E. and Dowling, Thomas P F and Stokes, Chris R. and Hugenholtz, Chris H.},
  issn         = {0094-8276},
  keyword      = {drumlins,instability,megascale glacial lineations,paleolandscapes,ribbed moraines,rogen moraines},
  language     = {eng},
  month        = {07},
  number       = {14},
  pages        = {7572--7580},
  publisher    = {American Geophysical Union},
  series       = {Geophysical Research Letters},
  title        = {Subglacial bed form morphology controlled by ice speed and sediment thickness},
  url          = {http://dx.doi.org/10.1002/2016GL069558},
  volume       = {43},
  year         = {2016},
}