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| Titel |
Thaw lakes in the geological record and their significance for Pleistocene glacial methane emissions |
| VerfasserIn |
J. van Huissteden, C. Berrittella |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021744
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| Zusammenfassung |
| Thaw (or thermokarst) lakes are striking features of present-day arctic lowlands underlain by
permafrost, covering 20-50% of the land surface in some cases. Evidence from the geological
record shows that during the last glacial thaw lakes also occurred in lowlands within the
periglacial zone in Europe. Thaw lakes are found in river valley fills, in glacial and tectonic
basins. Thaw lakes in the sedimentary record are characterized by a succession of
features indicating the former presence of permafrost (ice wedge casts), followed by
permafrost degradation features (generally large cryoturbations), in turn overlain by
lacustrine deposits. These successions have been reported from several sites in
the Netherlands and Northern Germany. Stratigraphic information suggest that
these lakes were of widespread occurrence, and may have resulted from repeated
changes in the southern permafrost boundary during rapid climate shifts of the last
glacial.
CH4emission from thaw lakes in Siberia and Alaska contributes significantly to CH4
emission from northern wetlands. Likewise, also ancient thaw lakes may have contributed to
the CH4 emission that led to the CH4 spikes recorded in the ice cores during the last glacial.
For an estimation of glacial CH4 sources, the strength of the thaw lake source needs to be
quantified. |
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