Structure and changing dynamics of a polythermal valley glacier on a centennial timescale: Midre Lovénbreen, Svalbard

Abstract

[1] Most polythermal glaciers in Svalbard, other than those of surge type, have receded steadily since the early 20th century. Midre Lovénbreen, a slow-moving, 4-km-long valley glacier terminating on land, is a typical example, and its internal structures reflect changing dynamics over this period. The three-dimensional structural style of this glacier and the sequential development of structures have been determined from surface mapping, ground-penetrating radar, and numerical flow modeling. In order of formation the structures observed today at the glacier surface are (1) primary stratification that has become folded about flow-parallel axes; (2) axial plane longitudinal foliation associated with this folding; (3) several sets of intersecting crevasse traces; (4) arcuate upglacier-dipping fractures developed as part of a thrust complex near the snout; and (5) longitudinal splaying fractures in the snout area. The long-term evolution and dynamic significance of these structures can be ascertained from historical ground and aerial photographs. Modeling indicates that stratification and foliation continue to evolve today as a result of internal deformation, especially in zones of converging flow, where simple shear is most pronounced, but within the tongue are carried passively toward the snout. Crevasse traces appear to be no longer actively forming but are interpreted as relict structures when the ice was more dynamic and mostly wet based. The interpretation of arcuate fractures near the snout as thrusts is supported by the matching orientations of modeled strain ellipses, which illustrate the importance of longitudinal compression.

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

“…Longitudinal features, visible on the surface of the glacier at the southern side (Figure 5(a) and 5(c)), resemble longitudinal foliation reported from many glaciers worldwide (e.g. Goodsell, Hambrey, & Glasser, 2005;Hambrey, 1975;Hambrey et al, 2005;Jennings, Hambrey, Glasser, James, & Hubbard, 2015). These structures can be traced downflow into an ice-cored moraine complex, where they are still detectable as linear structures (Figure 5(b)) on the surface of the moraine.…”

Possible interactions between bacterial diversity, microbial activity and supraglacial hydrology of cryoconite holes in Svalbard

“…First, each of the glaciers included in the study has a unique shape and basal boundary. These differences manifest themselves as correspondingly unique flow fields and structural configurations (Hambrey et al, 2005). As detailed patterns of surface meltwater drainage are to some degree controlled by glacier structure, it follows that at least the detail of each glacier's supraglacial meltwater network will be different.…”

Ice-cored moraine degradation mapped and quantified using an unmanned aerial vehicle: A case study from a polythermal glacier in Svalbard

“…The potential for surge-type behaviour at adjacent glaciers on Brøggerhalvøya has been discussed (e.g. Hansen, 2003;Glasser et al, 2004;Hambrey et al, 2005) and disputed (e.g. Jiskoot et al, 2000;King et al, 2008).…”