The structural glaciology of Kongsvegen, Svalbard, and its role in landform genesis

Abstract

ABSTRACT. Mapping of the structural glaciology of Kongsvegen, Svalbard, reveals cvidence for four main deformational structures. These are stratifi cation, longitudina l foli ation, thrusts a nd crevasse traces. These structures a re considered in terms of th eir contribution to debris entrainment, transport a nd subsequ ent landform development. Stratification is associated with sm a ll amounts of supraglacial debri s that has been folded with fl ow-pa rall el axes; longitudin al foliati on in pl aces incorporates basal glacial sediments along folds with fl ow-pa rallel axes; and thrusts tra nsport basal debris to the glacier surface. Crevasse traces a re not sig nificant in terms of debris entrainment. The entra inm ent of basal debris along longitudinal foli ation is not a universally recognised process. At Kongsvegen this process is attributed to the development of a tra nsposition foliation, in combination with incorporation of debris-rich basal ice or soft basal sediment in the fo ld complex. M apping of the landforms in th e proglacia l a rea shows th a t debris incorpora ted along longitudina l foli ati on is released as "foli ation-pa rall el ridges" a nd th at tra nsverse ridges mark debri s-bearing thrusts. The role of longitudinal foli ation in land form devclopment has never been documented in this manner. Although the preser vation potentia l of such ridges m ay be limited, recog nition of foli a tio n-pa rall el ridges in the Pleistocen e landform record h as important impli cations fo r the interpretati on of th e d ynamics of form er ice m asses.

Landscape evolution and ice-sheet behaviour in a semi-arid polar environment: James Ross Island, NE Antarctic Peninsula

“…Identification of glacially associated landforms from remote images is well established Glasser et al , 2009aGlasser et al , 2009b. Remotely sensed structural glaciological mapping followed standard procedures (Hambrey & Dowdeswell 1994, 2000Glasser et al 1998Glasser et al , 2011Hambrey et al 2005). Landforms and sediments and were mapped and logged in the field following procedures outlined in Gale & Hoare (1991), Jones et al (1999) and Evans & Benn (2004).…”

Imaging glacial sediment inclusions in 3‐D using ground‐penetrating radar at Kongsvegen, Svalbard

“…The lower regions of Kongsvegen are thought to be underlain by glaciomarine sediments, which have been incorporated into the bulk glacier ice by mechanisms variously interpreted as thrusting (Bennett et al, 1996;Hambrey et al, 1999;Hubbard et al, 2004), folding subparallel to glacier flow (Glasser et al, 1998;Hambrey et al, 1999) or crevasse filling . Thrusting results in zones of strong compression and causes fractures extending asymptotically from the glacier bed towards the surface (Hambrey et al, 1999).…”

“…Surge-type glaciers overlying sedimentary beds often have thick basal ice sequences (e.g., Murray et al, 1997) and contain large amounts of included sediment (Clapperton, 1975). Particular attention has been paid to the incorporation of sediment by the processes of thrusting (Murray et al, 1997;Hambrey et al, 1999;Hubbard et al, 2004), folding (Glasser et al, 1998;Hambrey et al, 1999) and crevassing (Sharp, 1985a,b;Woodward et al, 2003). Particular attention has been paid to the incorporation of sediment by the processes of thrusting (Murray et al, 1997;Hambrey et al, 1999;Hubbard et al, 2004), folding (Glasser et al, 1998;Hambrey et al, 1999) and crevassing (Sharp, 1985a,b;Woodward et al, 2003).…”

Glacigenic clast fabrics: genetic fingerprint or wishful thinking?

“…Meltout till. These deposits were formed by the meltout of debris-rich glacial structures, in particular the meltout of longitudinal debris pods associated with foliationparallel folding (Bennett et al, 1996a;Glasser et al, 1998). 3.…”

“…This reflects variations in the ice geometry at each site and the amount of gravity driven disturbance that occurred during formation. The meltout tills were formed by the ablation of debris-rich ice structures, particularly foliation-parallel debris pods (Glasser et al, 1998). The amount of disturbance during meltout is determined by the local ice topography around each of these debris-rich structures; steep slopes lead to greater disturbance.…”