Direct AMS 14C analysis of carbonate

Quan Hua, Vladimir Levchenko, Matthew Kosnik

Research output: Contribution to journalConference paperpeer-review

Abstract

We have investigated the possibility of direct accelerator mass spectrometry radiocarbon (AMS 14C) measurement of carbonate samples at ANSTO using the STAR 2 MV tandem accelerator. Each carbonate sample was powdered, mixed with metal powder and pressed into an aluminum cathode for direct carbonate measurement by AMS 14C. Of the three high-purity metal powders (Fe, Nb, and Ag) used in our investigation, Nb was found to be the best metal, which delivered higher carbon beam currents and lower background. Beam currents for targets containing the optimal carbonate mass of 1.5–2.0 mg were ∼8% of those obtained from graphite targets of standard size (>0.5 mg C). Typical measured blank for Carrara marble (IAEA-C1) of ∼40 ka was obtained. Background-corrected 14C values of carbonate targets agreed well with their associated values obtained from high-precision analysis of graphite targets within 2σ uncertainties. Typical precision of this rapid AMS analysis was ∼1% for samples <8 ka. Despite lower precision for carbonate target ages (compared to standard graphite target ages), these ages are useful for palaeobiological applications where a large number of dates are required, such as time-averaging studies.
Original languageEnglish
Pages (from-to)1431-1440
Number of pages9
JournalRadiocarbon
Volume61
Issue number5
Early online date15 Apr 2019
DOIs
Publication statusPublished - Oct 2019
EventInternational Radiocarbon Conference (23rd : 2018) - Trondheim, Norway
Duration: 17 Jun 201822 Jun 2018

Keywords

  • carbonate
  • radiocarbon AMS dating
  • shells
  • Sydney Harbour
  • time-averaging

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