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Graphitization of small carbonate samples for paleoceanographic research at the godwin radiocarbon laboratory, University of Cambridge

Accepted version
Peer-reviewed

Repository DOI


Type

Article

Change log

Authors

Freeman, E 
Skinner, LC 
Reimer, R 
Scrivner, A 
Fallon, S 

Abstract

jats:titleAbstract</jats:title>jats:pA 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 jats:sup14</jats:sup>C 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.</jats:p>

Description

Keywords

Radiocarbon analysis, target preparation, graphitization, geochemistry, geophysics, AMS dating, carbonate samples, paleooceanography, fractionation, reduction, graphite, fractionation

Journal Title

Radiocarbon

Conference Name

Journal ISSN

0033-8222
1945-5755

Volume Title

58

Publisher

Cambridge University Press (CUP)
Sponsorship
Natural Environment Research Council (NE/L006421/1)
We would like to thank James Rolfe for running the stable isotope measurements, as well as the Royal Society and NERC grant NE/L006421/1 for research support.