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14C AMS Dating of Icelandic Lake Sediments

Published online by Cambridge University Press:  18 July 2016

Árný E. Sveinbjörnsdóttir ,
Jan Heinemeier ,
Peter Kristensen ,
Niels Rud ,
Áslaug Geirsdóttir  and
Jórunn Harđardóttir
Árný E. Sveinbjörnsdóttir
Affiliation:
Science Institute, University of Iceland, Dunhagi 3, IS-107 Reykjavik, Iceland
Jan Heinemeier
Affiliation:
AMS 14C Dating Laboratory, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark
Peter Kristensen
Affiliation:
Department of Earth Sciences, University of Aarhus, DK-8000 Aarhus C, Denmark
Niels Rud
Affiliation:
AMS 14C Dating Laboratory, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark
Áslaug Geirsdóttir
Affiliation:
Department of Geosciences, University of Iceland, IS-101, Reykjavik, Iceland
Jórunn Harđardóttir
Affiliation:
INSTAAR, Campus Box 450, University of Colorado, Boulder, Colorado 80309, USA
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Abstract

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We report an age-depth profile for the sediments of the Lake Hesrvatn, southern Iceland, based on 14C analyses of the organic fraction of bulk sediment samples, molluscs and foraminifera. Our age-depth curve is supported by the occurrence of the well-dated Vedde ash in the lowermost part of the sediments. Comparison of foraminifera dates with the age of the Vedde ash indicates a reservoir age of ca. 400 yr. The results suggest that the sediments at Hestvatn accumulated in a marine environment until ca. 8700 bp and thereafter in freshwater.

Owing to the lack of terrestrial macrofossils and the low concentration of molluscs and foraminifera, we were forced to attempt to date most of the core with the organic fraction of the bulk sediment samples. We found, however, that this fraction is not homogeneous in density or 14C age. We believe that during sample pretreatment we managed to isolate a light organic fraction, which closely represents the true age of the sediment, whereas the denser fraction yields ages that are too high. This age diversity may to some extent be explained by the large drainage area of the lake, from which plant remains of different ages may have been washed into the lake.

Type
Part 2: Applications
Information
Radiocarbon , Volume 40 , Issue 2: 16th International Radiocarbon Conference June 16-20, 1997 Part 2: Applications, Conference Editors: Willem G. Mook Johannes van der Plicht , 1997 , pp. 865 - 872
Copyright
Copyright © The American Journal of Science 

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