Lindén, M. and Möller, P. 2005. Marginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession. J. Quaternary Sci., Vol. 20 pp. 113–133. ISSN 0267-8179.
Marginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession†
Version of Record online: 18 FEB 2005
Copyright © 2005 John Wiley & Sons, Ltd.
Journal of Quaternary Science
Volume 20, Issue 2, pages 113–133, February 2005
How to Cite
Lindén, M. and Möller, P. (2005), Marginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession. J. Quaternary Sci., 20: 113–133. doi: 10.1002/jqs.902
- Issue online: 18 FEB 2005
- Version of Record online: 18 FEB 2005
- Manuscript Accepted: 20 NOV 2004
- Manuscript Revised: 11 NOV 2004
- Manuscript Received: 16 APR 2004
- De Geer moraines;
- glacial sedimentology;
- subaqueous deglaciation;
- grounding line;
- deforming bed
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. Copyright © 2005 John Wiley & Sons, Ltd.