Palaeoseismicity and De Geer Moraines

Lundqvist, Jan

doi:10.1016/s1040-6182(00)00042-2

Cited by 12 publications

(9 citation statements)

References 33 publications

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“…Zilliacus (1985Zilliacus ( , 1987Zilliacus ( , 1989 investigated De Geer moraines in Finland, and he also suggested formation by subglacial squeeze into crevasses, although into sets of basal transverse crevasses initiated by glacial surges. This view has also been supported by Lundqvist (1989Lundqvist ( , 2000. The ice-surge hypothesis by Zilliacus does not, however, take into account-or explain-the classical calving bay configuration seen in many De Geer moraine areas (Strö mberg, 1981(Strö mberg, , 1989.…”

Section: De Geer Moraines-previous Workmentioning

confidence: 91%

“…Another possibility touched upon by De Geer (1940) for formation of subglacial crevasse systems is seismic activity in connection with isostatic rebound during the deglaciation. This JOURNAL OF QUATERNARY SCIENCE was further elucidated by Lundqvist (2000), arguing that the spatial distribution of De Geer moraines in Fennoscandia corresponds to known areas with high palaeoseismic activity. However, as it has not been proved by sedimentological evidence that De Geer moraines consist of crevasse-infill tills, as most existing sedimentological data point towards formation at retreating grounding lines and as seismicity-induced crevasse pattern cannot explain the topography-dependent spatial distribution and undulating configuration of De Geer moraine tracts, it must be ruled out that palaeoseismic activity has anything to do with De Geer moraine formation sensu stricto, other than possibly triggering major calving events.…”

Section: Density-flow Settlingmentioning

confidence: 92%

“…A large number of papers propose formation of De Geer moraines due to squeeze of water-saturated till into submarginal transverse crevasses (e.g. Elson, 1957;Hoppe, 1957Hoppe, , 1959Andrews, 1963aAndrews, , 1963bStrö mberg, 1965;Andrews and Smithson, 1966;Zilliacus, 1985Zilliacus, , 1987Zilliacus, , 1989Lundqvist, 1989Lundqvist, , 2000. However, none of these studies presents any sedimentological evidence for the proposed process.…”

Section: Model Comparisonsmentioning

confidence: 99%

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

Lindén

Möller

2005

J Quaternary Science

124

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Lindén, M. and Mö ller, P. 2005. Marginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession.ABSTRACT: 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 À1 ) 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.

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Section: De Geer Moraines-previous Workmentioning

confidence: 91%

Section: Density-flow Settlingmentioning

confidence: 92%

Section: Model Comparisonsmentioning

confidence: 99%

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

Lindén

Möller

2005

J Quaternary Science

124

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“…De Geer moraines have been variously described in the literature [14,56,86], but in fjords on Svalbard similar ridges have always been interpreted as either annual push moraines deposited during overall glacier retreat or as crevasse-squeeze ridges formed after surge termination [10,29,63,66,74]. Based on their dimensions and morphology, some of the De Geer moraines in Kongsfjorden appear similar to annual push moraines described from e.g.…”

Section: De Geer Morainesmentioning

confidence: 96%

“…[14,86]). De Geer moraines form subaquatically and typically occur as sets of transverse, parallel, irregularly spaced ridges that are around 3 m high, several hundred m long and up to 30 m wide [56,86]. Two main mechanisms have been proposed for their formation: (1) the ridges are annual end moraines composed of subglacial sediment pushed up at the glacier grounding line (e.g.…”

Section: Small Predominantly Transverse Ridges: De Geer Morainesmentioning

confidence: 99%