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| Titel |
Long-term sediment yield of the Austdalsbreen glacier, southwest Norway |
| VerfasserIn |
Mengzhen Xu, Jim Bogen, Galina Ragulina, Adrian Read |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101938
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| Publikation (Nr.) |
 EGU/EGU2015-1204.pdf |
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| Zusammenfassung |
| Long-term sediment yield of Austdalsbreen glacier, an eastern outlet glacier of Jostedalsbreen
ice cap in southwest Norway, was investigated by studies of sedimentation rates in the
proglacial lakes Austdalsvatn and Styggevatn, along with subglacial topography radar survey
and seismic surveys of the lake bed sediment. Sediment cores were taken from
both lakes. Annual sedimentation throughout the cores was identified from high
resolution photographs and X-ray scan analyses and was confirmed by three accelerator
mass spectrometry (AMS) 14C datings. The seismic survey profiles revealed the
distribution of these sediments. The impact of the subglacial topography on the
sediment delivery from upstream, along with grain-size distribution and organic content
analyses, were also taken into account in the interpretation of sediment cores. Possible
impact of climate change on sediment delivery from the glacier was discussed by
comparison of the average lake sedimentation rates during different periods of postglacial
time. Around calibrated years 9000–8870 BP, Austdalsbreen glacier was subject to
rapid retreat and calving. It was found that the glacier retreated rapidly from its
maximum extension, which had totally covered the two lakes, in the 130 yrs in the
early Holocene. About 1.4 million tons suspended load was delivered from the
glacier during this short period, giving an average sediment yield of 400 t/yr km2.
Such a high sediment yield was found to be due to rapid calving, fast ice motion,
abundance of meltwater, and larger areal extension and volume of the glacier at
that time. The glacier probably disappeared from the catchment around 6000 BP.
The glacier advanced after the 1100s, reaching its Little Ice Age maximum before
retreating to its present position. About 3.5 million tons suspended load was delivered
from the glacier during the 800 yrs from 1186 to 1986 AD, corresponding to an
average sediment yield of 290 t/yr km2, 30% lower than that of the early Holocene
retreat. This difference is probably mostly due to the smaller volume of the modern
glacier.
Keywords: long-term sediment yield, postglacial time, proglacial lake, sediment core,
seismic survey |
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