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Titel |
Post-glacial rebound of Iceland during the Holocene |
VerfasserIn |
Eline Le Breton, Olivier Dauteuil, Guillaume Biessy |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250034581
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Zusammenfassung |
The geodynamic context of Iceland provides the rare opportunity to analyse the combined
effect of ridge and hot spot on the deformation processes. The ground deformation results
from rifting, magmatic (hot spot and volcanism) and ice loading/unloading. We present in this
study a quantitative synthesis of vertical crustal motions of Iceland during the Holocene time
with a focus on the postglacial isostatic rebound around the whole island after the retreat of
the Weichselian ice cap.
Quantitative information, amounts and rates, of the postglacial rebound are
obtained from sea levels deduced from elevated beach terraces, marine cliffs and
deposits. From digital elevation models, field study, and a synthesis of previous
works, we determined two ancient marine limits, one above and one below the
present sea level, estimated at 10 ka ±300 and 8150 ±350 yrs BP respectively. The
amplitude and the rate of vertical motions undergone by the Icelandic lithosphere were
calculated from these marine levels, once their elevations were corrected with sea level
changes.
We calculated an uplift phase of 40 to 170 m with a rate of 2.1 to 9.2 cm/yr between 10 ka
±300 and 8150 ±350 yrs BP. This stage corresponds to the postglacial rebound of
Iceland following the Weichselian deglaciation. The analysis of variability of the
uplift does not reveal a strong correlation with geodynamic structures (rift, thermal
anomalies, and eruptive centres). Spatial variations of the postglacial rebound are
mainly related to the local glacial dynamics (ice load and deglaciation history) rather
than the geodynamic context. However, the relaxation time deduced from uplift
data is 4167 years in west Iceland and 2000 years in south-southwest Iceland. We
estimated viscosity from relaxation time, ranging from 2.1.1019Pa.s to 3.2.1019
Pa.s. The significant difference in the relaxation time is due to local variation of
the lithospheric thickness due to the rift rather than to a variation of the viscosity. |
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