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| Titel |
New exposure ages from Erratic-boulders in the lower Reuss-valley (Switzerland) |
| VerfasserIn |
Regina Reber, Naki Akçar, Susan Ivy-Ochs, Peter W. Kubik, Christian Schlüchter |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053984
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| Zusammenfassung |
| For the understanding of the climate system dynamics, it is important to have a closer look at
global climate change signals and their terrestrial documents. Therefore timing of advance
and retreat of glaciers in the past is important. During the last glacial maximum (LGM), huge
piedmont lobes covered large areas of the northern Alpine foreland. This is evidenced by
distribution of erratic boulders. In order to get the timing of the LGM, erratic boulders, which
mark the terminus of piedmont glaciers at that time, can be exposure dated with
cosmogenic nuclides. Particularly in the Alpine foreland, it is difficult to find good
boulders because of the anthropogenic impact. Humans used the erratic boulders
or parts of them as building stones, destroyed or displaced them for agricultural
purposes. So there are only few potential sampling sites available for surface exposure
dating.
In the lower Reuss-valley we sampled three boulders for surface exposure dating with
cosmogenic 10Be. Anthropogenic effects on the boulders seems to be unlikely in field but
cannot be excluded before the results are available. Two boulders are located on moraines
belonging to the LGM maximum extent of Mellingen, which can be chronologically
correlated with the “Killwangenstadium” from the Linth/Rhein piedmont lobe. The third
boulder is situated between two retreating stadial positions, the local “Rückzugsstadien von
Stetten I & II” which are correlated with the “Schlierenstadien”. In the chronological aspect,
the third boulder belongs to the phase of deglaciation of the lower foreland. The time between
the maximum extent and the recession of the Schlieren stadials is dated between around
32000 cal. BP and 23000 cal. BP with radiocarbon. Our results will contribute
to the understanding of the timing of processes during and especially at the end
of the LGM. Furthermore they will give a control of the radiocarbon chronology. |
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