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Supraglacial moraines in Scharffenbergbotnen, Heimefrontfjella, Dronning Maud Land, Antarctica – significance for reconstructing former blue ice areas

Published online by Cambridge University Press:  06 June 2005

CLAS HÄTTESTRAND
Affiliation:
Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden, clas.hattestrand@natgeo.su.se
NINA JOHANSEN
Affiliation:
Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden, clas.hattestrand@natgeo.su.se

Abstract

The ice surface of the glacier in the 7 km long valley Scharffenbergbotnen in Heimefrontfjella, Dronning Maud Land, is characterized by blue ice fields and is partly covered by supraglacial moraine complexes. The debris cover of the supraglacial moraines is generally less than 50 cm thick and rests on glacial ice, and most of the surface morphology of ridges and numerous sink holes reflects irregularities in the underlying ice. The debris consists of angular to sub-angular clasts of local bedrock. We interpret the moraines to have an entirely supraglacial history, where colluvium and pre-existing moraines were brought into Scharffenbergbotnen primarily from the south/south-west by an advancing glacier during the last ice maximum in the region. The debris cover of the supraglacial moraines extends up to 200–250 m above the present ice surface on surrounding slopes in Scharffenbergbotnen, and generally to less than 100 m above the present ice surface on slopes outside the valley. We interpret this as marking the ice surface elevation in the area during the last ice maximum (probably LGM). The deposition of supraglacial moraines in the valley at that time, and their survival in the area until the present day, indicate that a local ablation centre and probably blue ice fields were present in Scharffenbergbotnen at LGM, and has been a persistent feature since. In a wider context, we argue that supraglacial moraines constitute a hitherto unexploited resource when reconstructing the former extent of blue ice areas.

Type
Research Article
Copyright
© Antarctic Science Ltd 2005

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