Online Diary: ICE MARGINAL TERRESTRIAL LAND SYSTEMS: SVALBARD POLYTHERMAL GLACIERS

Geomorphology and sedimentology of receding Svalbard Glacier

Ice Push versus thrusting of sediment

Moraine mound complex – huge moraine systems in front of receding Svalbard Glacier

Morphology: arcuate belts of aligned hummocks or mounds comprising of morphological types
· Linear ridges – 100 m long
· Short crested ridges – several metres long
· Near conical mounds – reaching elevations of several metres

Ice proximal rectilinear or curvilinear slopes with consistent angle of around 30*, irregular distal slopes that are commonly steeper

Thrusting & stacking of thick sediment wedges – survival of initial moraine morphology

Other constructional Landform

Linear debris stripes – folding of supraglacially derived layers in the ice derived from folded stratified layers and emerge at the glacier surface as medial moraines as a result of ablation near the snout. Regular stripes of angular debris extending for considerable distances across the proglacial area. Debris stripes recognized by their angular unilithological nature and lack of fine matrix

Foliation-parallel layers – basally derived debris. Surge type Kongsvegen, Vestre Lovenbreen. Result of melting of ice core – mechanism à lateral compression of ice leads to the development of a transposition foliation parallel to the flow combined with the incorporation of basal debris-rich ice or soft basal sediment infold complex

Geometrical ridge network – created when both longitudinal and tranverse debris accumulates, meltout of glacier and become superimposed

Flow parallel ice structures – Marthabreen

2 types : Longitudinal sediment structures – ridges of sand and gravel, sub parallel to foliation fill consists of fine sand and gravel

Longitudinal ridge accumulations – larger ridges, occur downstream of sediment structures

Streamlined ridges – forefield of Austre & middle lovenbreen – elongated in the direction of glacier flow at glacier margin, emerge from beneath receding glacier margin

Landsystem model for Svalbard Glacier

3 zones within its forefield

Outer moraine ridge – arcuate ridges rsing steeply from surrounding topography, ice cored, product of permafrost deformation, englacial or proglacial thrusts
Moraine-mound complex – arcuate belts of aligned hummocks, include linear ridges, short crested ridges, near conical mounds. High friction at decollement surface –

thrust dominated moraine complex (Comfortlessbreen, Uverbreen, Krone Breen)
permafrost areas – proglacial deformation (erikbreen, Usherbreen)
low friction at glacier bed – polyphase folding (sefstrombreen)

Inner Zone – between moraine mound complex and modern glacier snout. Foliation parallel ridges, supraglacially derieved stripes of debris, geometrical ridge networks, streamlined ridges, flutes.

	GLACIAL LANDFORM	LOCATION

Ice margin terrestrial land systems: sub polar glacier margins of the Canadian and Greenland high arctic	Valley Glaciers	Vestre lovenbreen, Midtre Lovenbreen, Austre Lovenbreen, Pedersenbreen, Botnfjellbreen
	Valley glaciers with prominent outer moraine ridge, with moraine mound complexes, glacifluvial facies and linear debris dtripes	Midtre Lovenbreen, Austre Lovenbreen
	Linear debris stripes	Austre Broggerbreen
	Moraine Mound Complex (hummocky moraine)	Kronebreen
	Group of small flutes	Midtre Lovenbreen