Jökull - 01.01.2012, Blaðsíða 153

Reviewed research article
Surge fingerprinting of cirque glaciers at the Tröllaskagi
peninsula, North Iceland
Skafti Brynjólfssona,b,c, Ólafur Ingólfssonc and Anders Schomackerb
aIcelandic Institute of Natural History, Borgir, Norðurslóð, IS-602 Akureyri, Iceland
bNorwegian University of Science and Technology (NTNU),
Department of Geology, Sem Sælands Veg 1, N-7491 Trondheim, Norway
cUniversity of Iceland, Institute of Earth Sciences, Askja, Sturlugata 7, IS-101 Reykjavík, Iceland
Corresponding author: skafti.brynjolfsson@ntnu.no
Abstract – The geomorphology and sedimentology of the Teigarjökull and Búrfellsjökull, two small surge-type
cirque glaciers at the Tröllaskagi peninsula, northern Iceland was explored for improved understanding of their
surge imprints. Geomorphological, geological and remote sensing data on sediments and landforms were used
for developing a geomorphological model for surge-type cirque glaciers in Iceland. Most surge moraines iden-
tified are in the form of uneven small ridges or debris sheets that constitute a boulder-rich hummocky terrain.
The size and structures of two moraines in front of Teigarjökull are interpreted as suggesting that the glacier
has in the past switched between surge and non-surge behavior. Hummocky surfaces, small medial moraines
and crevasse-fill ridges are common, as are landforms suggesting dead-ice melting, such as backslumping, ex-
tension cracks and sinkholes. The surface sediments are rich in subangular and angular pebbles, cobbles, and
boulders. This distinct geomorphology of the glacier forefields results from ample supply of coarse and angular
sediments originating from the steep mountain slopes bordering the glaciers and subsequently carried to the
marginal zone via englacial and supraglacial transport.
Key words: Surge-type glaciers, glacial geomorphology, Búrfellsjökull, Teigarjökull
INTRODUCTION
Glacier surging represents cyclic glacier flow instabil-
ity, and surging glaciers undergo systematic changes
in morphology and behavior during a surge cycle
(Raymond, 1987). A surge cycle consists of a mul-
tiyear quiescent phase and a fast-flow surge phase.
The surge phase involves a transfer of ice from the
accumulation area to the glacier margin, resulting in a
rapid advance (Thórarinsson, 1964, 1969; Meier and
Post, 1969; Raymond, 1987; Björnsson et al., 2003;
Evans and Rea, 2003). The quiescent phase is char-
acterized by stagnation of the snout and ice build-up
in the accumulation area. Thus, the glacier profile be-
comes steeper and finally reaches a threshold which
results in a new surge (Post, 1969; Raymond, 1987;
Paterson, 1994; Evans and Rea, 2003).
Both temperate and subpolar glaciers, in Alaska,
Canada, Chile, Himalaya, Iceland, Pamir, Russia and
Svalbard, have been identified as surge-type glaciers
(e.g. Paterson, 1994; Benn and Evans, 2010). They
often occur in clusters indicating that local subglacial
and environmental conditions may control whether a
glacier is surge-type or not (Paterson, 1994; Harri-
son and Post, 2003). Surging is generally believed
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