Assemblages of submarine landforms produced by tidewater glaciers in Svalbard

Abstract

[1] High-resolution swath bathymetry from the marine margins of several Svalbard tidewater glaciers shows an assemblage of submarine landforms that is probably linked to glacier surging. These landforms are essentially unmodified since their initial deposition over the past hundred years or so because they have not been subjected to subaerial erosion or periglacial activity. Swath images comprise an assemblage of superimposed landforms, allowing reconstruction of relative age of deposition: (1) large transverse ridges, interpreted as recessional moraines overridden by a subsequent ice advance; (2) a series of curvilinear streamlined bedforms orientated parallel to former ice flow, interpreted as lineations formed subglacially during rapid advance; (3) large terminal ridges, marking the farthest extent of ice at the last advance, with flow lobes immediately beyond interpreted as submarine debris flows; (4) a series of interconnected rhombohedral ridges, interpreted as a product of soft sediment squeezing into crevasses formed at the glacier bed, probably formed during immediate post-surge stagnation; and (5) a series of fairly evenly spaced small transverse ridges, interpreted as push moraines produced annually at tidewater glacier termini during retreat. A simple descriptive landsystem model for tidewater glaciers of probable surge type is derived from these observations. We also show that megascale glacial lineations can form not only beneath large ice streams, but are also produced beneath surging tidewater glaciers lying on deforming sedimentary beds.

Glacial geomorphology of the terrestrial margins of the tidewater glacier, Nordenskiöldbreen, Svalbard

“…However, the landform assemblage observed at Nordenskiöldbreen is complex and different from the assemblages described for forelands located in a valley setting or tidewater surging glaciers (cf. Bennett et al, 1996;Bennett, Hambrey, Huddart, Glasser, & Crawford, 1999;Boulton et al, 1996;Kristensen, Benn, Hormes, & Ottesen, 2009;Lønne, 2014aLønne, , 2014bLovell et al, 2015;Ottesen & Dowdeswell, 2006).…”

Submarine landform assemblages and sedimentary processes related to glacier surging in Kongsfjorden, Svalbard

“…The high detail preserved in submarine environments offers invaluable insights into the processes controlling landform genesis, and, together with lithological records from sediment cores, enables a better understanding of tidewater glacier sedimentation and dynamics (e.g. [10,63,66]). …”

“…Many Svalbard glaciers have been identified as surge-type (e.g. [15,35,53,63,66,67]), with surges well-documented from the past c. 180 years, but only two older examples (Paulabreen and Nathorstbreen; [35,36,46,49,53]). …”

“…[10,20,22,25,63,66,71,73]). Landforms related to glacier surges in submarine settings have been described from several Spitsbergen fjords [3,10,29,63,66,67].…”

“…[10,20,22,25,63,66,71,73]). Landforms related to glacier surges in submarine settings have been described from several Spitsbergen fjords [3,10,29,63,66,67]. The landform models suggested thus far include overridden recessional moraines, (mega-scale) glacial lineations, terminal moraines with associated sediment lobes on their distal slopes, eskers, annual push moraines and crevasse-squeeze ridges, the latter suggested to be the only feature diagnostic of a glacier surge [66,71].…”