d13C analysis

[fiona beglane]

Hi

Probably more of a radiocarbon question than an Oxcal question but I wonder if someone could enlighten me. 

I am using a different RC lab from my usual lab because I have been offered funded dates there. The samples are wood charcoal. They have asked if I want d13C results - for an extra charge. I have not been asked this before. My usual lab provides these figures for bone but not for charcoal or wood but for wood and charcoal results that I have had previously they have stated 'fraction corrected d13C'.  

What would be the advantage of having these d13C values for wood charcoal? How might they be useful? I don't want to incur cost needlessly, but equally don't want to miss out on something useful.

Thank you

Fiona

[Bayliss, Alex]

Hi Fiona,

 

All radiocarbon ages should be corrected for fractionation. Nowadays most AMS laboratories do this using a value measured on-line in the AMS. This is good for age calculation (because it includes any fractionation introduced in the graphitisation and measurement process) but does not give you a useful measure of the natural isotopic composition of the dated material. This is of interest, for example, for bones because the natural isotopic composition may give you useful information on dietary effects. These values are usually measured by IRMS.

 

What a given laboratory reports is another matter!! Some laboratories report the AMS value that they use in age calculation; some laboratories use this for age calculation but do not report it (reporting instead the value measured by IRMS).; some laboratories report both! 😊 Hopefully, this information should be on the dating certificate.

 

Alex

 

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From: 'fiona beglane' via OxCal <ox...@googlegroups.com>
Sent: 14 February 2025 18:07
To: OxCal <ox...@googlegroups.com>
Subject: d13C analysis

 

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[fiona beglane]

Thank you Alex - sounds like I need to go back to them and clarify.

I have used stable isotopes for dietary analysis before for bone. But have rarely dated charcoal previously.

Fiona