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Graphitization of Small Carbonate Samples for Paleoceanographic Research at the Godwin Radiocarbon Laboratory, University of Cambridge

Published online by Cambridge University Press:  05 January 2016

E Freeman ,
L C Skinner ,
R Reimer ,
A Scrivner  and
S Fallon
E Freeman*
Affiliation:
Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, CB2 3EQ, UK.
L C Skinner
Affiliation:
Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, CB2 3EQ, UK.
R Reimer
Affiliation:
CHRONO Centre, Queen’s University Belfast, Belfast, BT9 6AX, UK.
A Scrivner
Affiliation:
Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, CB2 3EQ, UK.
S Fallon
Affiliation:
Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia.
*
*Corresponding author. Email: [email protected].
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Abstract

A new radiocarbon preparation facility was set up in 2010 at the Godwin Laboratory for Palaeoclimate Research, at the University of Cambridge. Samples are graphitized via hydrogen reduction on an iron powder catalyst before being sent to the Chrono Centre, Belfast, or the Australian National University for accelerator mass spectrometry (AMS) analysis. The experimental setup and procedure have recently been developed to investigate the potential for running small samples of foraminiferal carbonate. By analyzing background values of samples ranging from 0.04 to 0.6 mg C along with similar sized secondary standards, the setup and experimental procedures were optimized for small samples. “Background” modern 14C contamination has been minimized through careful selection of iron powder, and graphitization has been optimized through the use of “small volume” reactors, allowing samples containing as little as 0.08 mg C to be graphitized and accurately dated. Graphitization efficiency/fractionation is found not to be the main limitation on the analysis of samples smaller than 0.07 mg C, which rather depends primarily on AMS ion beam optics, suggesting further improvements in small sample analysis might yet be achieved with our methodology.

Keywords

Radiocarbon analysistarget preparationgraphitizationgeochemistrygeophysicsAMS datingcarbonate samplespaleooceanographyfractionationreductiongraphitefractionation
Type
Research Article
Information
Radiocarbon , Volume 58 , Issue 1 , March 2016 , pp. 89 - 97
Copyright
© 2016 by the Arizona Board of Regents on behalf of the University of Arizona 

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References

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