Guidelines for the determination of ΔR values are given in Stuiver and Braziunas, 1993. The marine calibration dataset must be selected for calibrating these samples.
Reservoir deficiences R for lacustrine samples are typically determined from the age of the topmost sediments (e.g.
By measuring the radiocarbon age of tree rings of known or other independently dated samples it is possible to construct calibration datasets. The single year dataset UWSY98 (Stuiver et al 1998) is also still in use for short-lived samples 350 14C BP.
The need for a consensus radiocarbon calibration dataset led to the first internaltionally agreed upon calibration in 1982 (Klein et al., 1982). C yr BP, the single year calibration curve may be used for higher time resolution comparisons although a moving average of 2 to 3 years is recommended to reduce the noise and hence the number of cal ranges.
This reduces the detail in the calibration curve, irrelevant in this case, and minimizes the number of ranges and intercepts. the number of calendar years estimated for sample growth or formation) to use a moving average of the selected calibration curve.
Conventional radiocarbon ages have been corrected for isotope fractionation by normalizing to = -25 PDB or VPDB.
To accommodate local effects, the difference ΔR in reservoir age of the local region of interest and the model ocean should be determined.A calibration program for post-nuclear testing samples is available at before calibrating a radiocarbon age, the age should be adjusted for the laboratory systematic offset if any.Although international calibration efforts point towards the possibility of laboratory offsets (for summary, see Scott et al., 1998), specific laboratories have not been identified.The ΔR value must be determined as for marine samples above.The "mixed" marine and Northern or Southern atmospheric calibration curve should be selected for calibrating these samples.The adjustment for any systematic offset is not incorporated in this program.The standard deviation reported with a radiocarbon age may be based on count rate statistics only.A lab error multiplier is based on the overall reproducibility and should be supplied by the individual laboratory.The added variance option can be used by calculating the f value from: σC than their counterparts in the atmosphere.For samples derived from a mixture of marine and terrestrial carbon, such as bones of humans or animals with a mixed marine (fish, mollusk, plankton etc.) and terrestrial (grain, grass, other terrestrial animals etc.) diet, the percent of marine carbon should first be determined from other means, such as ethnohistorical accounts, dental pathology, archaeological evidence, or stable isotope composition (e.g.De Niro and Epstein, 1978; Ambrose and Norr, 1993; Molto et al., 1997).