How can you calibrate pMC dates? e.g. what would be the calibration values for 130±2 pMC.
pMC stands for "Percent Modern Carbon" as calculated against a reference sample of 14C activity from a known standard. Just knowing pMC will not allow you to calibrate a pMC value. You need to know several other values from the assay.
The U. Waikato radiocarbon laboratory has a thorough discussion of this and the calibration process: http://www.c14dating.com/agecalc.html
pMC is percent modern carbon, with modern or present defined as 1950. Of course as calibration is needed anyway you could just apply the formula and give a negative radio carbon age of minus 2150 years bp, but that'd be rather confusing. Since the atmospheric atom bomb tests of the fifties and sixties atmospheric radio carbon values have gone haywire, although they're nearing normal again now. So for anything younger than 1850 AD or so laboratories often do not give an age but the raw radiocarbon measurement as percent of the standard. It is up to you to try and make sense of it in the context of sample.
You can calibrate modern radiocarbon data (PMC or F14C) to a calendar age if you know some extra information (i.e. the area where your sample comes from and the year of analysis). You can find a good explanation in the CaliBomb page (http://calib.qub.ac.uk/CALIBomb/) and also do calibration online. It's really easy!!
If the measured radiocarbon concentration is higher than 100 pMC, it is evident that the sample is dated back to the Bomb Peak period. International agreed Bomb Peak curves are published: the most recent updated datasets have been published on Radiocarbon (Hua et al., Radiocarbon 55 (2013), p. 2059). Good softwares for calibration are Calibomb and OxCal.
Roughly speaking, and without knowing the exact location where your sample was taken, but using Levin's bomb curve correction, your date of 130±2 pMC equates to 1962 or 1978-80 at 2 sigma.
Dear @Kevin P. Smith Similar case is also with me and i have used CaliBomb software to calculate the age of the samples it showing some -calBP. Whether i will add it with 1950 or something else. Plz elaborate it. So what could be the age of the sample having pMC values =117.1 +/- 0.3 pMC.
It was analysed on the decomposed plant tissue mainly charred material, collected from East coast of India. IF possible plz help me.
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