Menu

Javascript is not activated in your browser. This website needs javascript activated to work properly.
You are here

Marginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession

Author:
  • Mattias Lindén
  • Per Möller
Publishing year: 2005
Language: English
Pages: 113-133
Publication/Series: Journal of Quaternary Science
Volume: 20
Issue: 2
Document type: Journal article
Publisher: John Wiley and Sons Inc.

Abstract english

De Geer moraine ridges occur in abundance in the coastal zone of northern Sweden, preferentially in areas with proglacial water depths in excess of 150 m at deglaciation. From detailed sedimentological and structural investigations in machine-dug trenches across De Geer ridges it is concluded that the moraines formed due to subglacial sediment advection to the ice margin during temporary halts in grounding-line retreat, forming gradually thickening sediment wedges. The proximal part of the moraines were built up in submarginal position as stacked sequences of deforming bed diamictons, intercalated with glaciofluvial canal-infill sediments, whereas the distal parts were built up from the grounding line by prograding sediment gravity-flow deposits, distally interfingering with glaciolacustrine sediments. The rapid grounding-line retreat (ca. 400 m yr(-1)) was driven by rapid calving, in turn enhanced by fast iceflow and marginal thinning of ice due to deforming bed conditions. The spatial distribution of the moraine ridges indicates stepwise retreat of the grounding line. It is suggested that this is due to slab and flake calving of the ice cliff above the waterline, forming a gradually widening subaqueous ice ledge which eventually breaks off to a new grounding line, followed by regained sediment delivery and ridge build-up.

Keywords

  • Geology
  • deforming bed
  • subaqueous deglaciation
  • De Geer moraines
  • glacial sedimentology
  • grounding line

Other

Published
  • ISSN: 1099-1417
Per Möller
E-mail: per [dot] moller [at] geol [dot] lu [dot] se

Professor

Quaternary Sciences

+46 46 222 98 88

508

16