Geomorphology and style of plateau icefield deglaciation in fjord terrains: the example of Troms‐Finnmark, north Norway

Abstract

In spite of a widespread distribution, the way in which plateau icefields affect the glaciation and deglaciation of adjacent terrains is not particularly well-known. This paper aims to identify how the deglaciation of the fjord and plateau terrain of north Norway has influenced the glacial geomorphology and relative sea-level history of both local and adjacent areas and so serve as a model for interpreting similar areas along the continental margins of northwest Europe and elsewhere. The identification of moraines and their relationships with the Main shoreline of northern Norway allows the margins of the Øksfjordjøkelen, Svartfjelljøkelen and Langfjordjøkelen plateau icefields to be identified in the adjacent terrains. In locations where ice margins are uncertain, it is also possible to reconstruct ice limits by means of glacier models appropriately constrained by known local conditions and dates. Earlier glacier margins, characterised in north Norway by ice shelves floating in the local inlets of major fjords, also can be related to known regional shorelines. The distribution of high shoreline fragments, augmented by radiocarbon dates, helps show the extent to which inter-island channels and outermost parts of fjords can become deglaciated relatively early in comparison with published maps of regional deglaciation. Plateau-icefield-centred glaciation became important sometime after 14 000 14 C yr BP and was characterised by glacier readvances up to, and in some locations beyond, earlier moraines and raised marine features. Although overlooked until recently, the identification of the influence of plateau icefields on local glaciation, and their interaction with local and regional marine limits, is of great importance in accurate palaeoenvironmental reconstruction.

Glacier fluctuations, equilibrium-line altitudes and palaeoclimate in Lyngen, northern Norway, during the Lateglacial and Holocene

“…19). This is comparable with estimates obtained from Øksfjordjøkulen, Svartfjelljøkulen and Langfjordjøkulen (Evans et al, 2002).…”

“…Hammarlund et al, 2002). Except for the 'Little Ice Age' (Gellatly, 1986;Whalley et al, 1989Whalley et al, , 1996Ballantyne, 1990;Gordon et al, 1996;Whalley and Kjøllmoen, 2000) and Younger Dryas (Evans et al, 2002), however, little is known about variations in the ELA of small glaciers during the Lateglacial and Holocene at the north-western coast of Scandinavia. With several small modern glaciers situated beyond the terminus of both the Skarpnes event and Younger Dryas Scandinavian ice sheets, the northern part of the Lyngen Peninsula (Figs.…”

GlaRe, a GIS tool to reconstruct the 3D surface of palaeoglaciers

“…However, the point of this exercise is to assess the quality of the reconstruction achievable replicating the situation where the icefield had disappeared and there were only ice geometry data available i.e. outlet glacier and plateau terminating moraines or precipitous plateau edges where ice avalanched off (Rea et al, 2000;Evans et al, 2002).…”

“…It is worth noting that for deglaciated plateau we would recommend reconstructing the moraine constrained outlet glaciers first. Then "tune" any flowlines, from the plateau margins where there are no moraines (needed to generate a complete icefield reconstruction), to fit where they meet the ice divides for the outlet glaciers (Evans et al, 2002). For the reasons outlined above portions of the flowlines near the central ice divide were assigned a shear stress of 50 kPa (see Figure 13).…”

Structure and sedimentology of George VI Ice Shelf, Antarctic Peninsula: implications for ice-sheet dynamics and landform development

“…This paper provides a detailed description of an ice-shelf moraine for the first time, and this can be used as a basis for locating such features in the geological record. Such features have already been identified in the Canadian Arctic (England et al 1978(England et al , 2009Hodgson & Vincent 1984) and northern Norway (Evans et al 2002), but there is no reason to suppose that they are not more widespread. The key identifiers are near-horizontal benches underlain by poorly sorted sediment, together with a scatter of local and fartravelled ice-transported boulders on the surface.…”