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| Titel |
Tracing Pleistocene to Holocene meltwater events and provenance of sediments
in Baffin Bay using radiogenic isotope signals |
| VerfasserIn |
Valeriia Kirillova, Simone A. Kasemann, Friedrich Lucassen |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127961
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| Publikation (Nr.) |
 EGU/EGU2016-7893.pdf |
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| Zusammenfassung |
| Large meltwater discharge is the principal carrier of detritus from the continent into the ocean
and the dispersion of this detritus by ocean currents is a measure for the spatially focused
addition of freshwater in the ocean in the high latitude areas. To trace Greenland ice sheet
dynamics and freshwater routing during late Pleistocene to Holocene climate transition, we
generate strontium (Sr), neodymium (Nd) and lead (Pb) isotope records on sediment cores in
the Baffin Bay: GeoTÜ SL 170, covering the last 18.000 years of climate history
and GeoTÜ SL 174, covering 40.000 years. Sr, Nd and Pb isotopes are used as
proxies for the provenance of continental detritus and seawater sources. Isotope
analyses were performed on two separated fractions from the sedimentary core
material: the chemically leached fraction and the remaining detritus. Leachates are
supposed to represent Fe-Mn coatings formed on the surface of the sediment grains
and to reflect the bottom water signal. The detrital fraction acts as a tracer for the
meltwater event and weathering regime of the nearby continental masses. For the
detrital fraction of the core SL 170, a pronounced shift can be observed in all three
isotope systems at ∼ 12 ka, what coincides with the Younger Dryas cold event. For
the detrital fraction the 87Sr/86Sr is around ∼0,72 before the event and reaches
up to ∼0,74 after. Nd isotope composition (ɛNd) changed from ∼-26 to ∼-32.
The shift suggests a change in the continental sources from West and West-South
Greenland to the Baffin Island and Canadian Archipelago. It can be explained by
the ice sheet melting processes. The 206Pb∕204Pb values for the detrital fraction
range from ∼17 before the shift to ∼18 after. On the contrary, the leachates show
pronounced radiogenic signatures with values changing from ∼21 to ∼23. The
reason for such an unusual high values is most likely in the composition of the
leached material, which doesn’t seem to show the presence of Fe-Mn coatings as
was suggested before. The work on the second core SL 174 is in progress. Up to
now the results show similar patterns for isotope ratios as in the case of SL 170. |
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