HR: 0800h
AN: C41A-0045    [Abstracts]
TI: Quantification of Dead-ice Melting in Ice-Cored Moraines at the High-Arctic Glacier Holmströmbreen, Svalbard
AU: * Schomacker, A
EM: anders@hi.is
AF: Institute of Earth Sciences University of Iceland, Askja Sturlugata 7, Reykjavik, IS-101, Iceland
AU: Kjaer, K H
EM: kurtk@snm.ku.dk
AF: Natural History Museum of Denmark Geological Museum University of Copenhagen, Oster Voldgade 5-7, Copenhagen, DK-1350, Denmark
AB: An extensive dead-ice area has developed at the stagnant snout of the Holmströmbreen glacier on Svalbard following its Little Ice Age maximum. Dead-ice appears mainly as ice-cored moraines, ice-cored eskers and ice- cored kames. The most common dead-ice landform is sediment gravity flows on ice-cored slopes surrounding a large ice-walled, moraine-dammed lake. The lake finally receives the sediment from the resedimentation processes. Dead-ice melting is described and quantified through field studies and analyses of high-resolution, multi-temporal aerial photographs and satellite imagery. Field measurements of backwasting of ice-cored slopes indicate short-term melting rates of c. 9.2 cm/day. Long-term downwasting rates indicate a surface lowering of ice-cored moraines of c. 0.9 m/yr from 1984-2004. Different measures for dead-ice melting are assessed in relation to the temperature record from Svalbard since the termination of the Little Ice Age. The most prominent impact of dead-ice melting is the evolution of the ice-walled lake with an area increasing near-exponentially over the last 40 years. As long as backwasting and mass movement processes prevent build-up of an insulating debris-cover and expose ice-cores to melting, the de-icing continues even though the area is characterized by continuous permafrost.
DE: 0700 CRYOSPHERE (4540)
DE: 0702 Permafrost (0475)
DE: 0720 Glaciers
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: 2007 Fall Meeting