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| Titel |
Constructing Antarctic lake chronologies: problems encountered and suggestions for the future studies |
| VerfasserIn |
Stephen Roberts, Dominic Hodgson, Elie Verleyen, Wim Vyverman, Mike Bentley |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076736
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| Zusammenfassung |
| In the early 1990s, Björck et al. identified several problems with the radiocarbon dating of
sediments from Antarctica, including the input of reworked older material or glacial
meltwater containing old CO2 and possible disequilibrium between lake carbon reservoirs
and atmospheric CO2, which can compromise the reliability lake chronologies. Over
twenty years later, often through necessity, many lake and marine studies still rely on
radiocarbon ages from bulk sediments which have mixed and/or uncertain sources
of carbon. In Antarctic lacustrine environments, low carbon and the absence of
macrofossils can limit the use of radiocarbon dating, while sediment deposition
under-ice or in darkness creates a fundamental problem for optically-stimulated
luminescence dating. Relatively low sedimentation rates interspersed with periods
of rapid deposition and/or reworking from variable and often unknown sources
can sometimes create conflicting chronological data, which can be challenging to
incorporate into a single, robust age-depth model, particularly when both marine
and terrestrial sediments are present in the same sequence. Here, using examples
from lake records collected over the last decade from the subantarctic islands, the
Antarctic Peninsula, and East Antarctica, we show how the BAS-Ghent-Durham lake
coring groups have worked towards addressing some of the issues identified by
Björck et al. We show how chronological data from lake records from the northern
Antarctic Peninsula region: 1) helped establish that the Last Glacial Maximum
ice volume on the Antarctic Peninsula was much smaller than some coupled ice
sheet/glacio-isostatic models had been predicting; 2) helped establish the reliability of
chronological models for the James Ross Island ice core record; 3) can be used to
provide better constraints on radiocarbon marine reservoir offsets. We also discuss
methods which could be used in the future to improve lake chronologies in Antarctica. |
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