Reservoir offset models for Radiocarbon calibration

The purpose of a reservoir offset is to enable the application of calibration data (μ(θ), e.g. Stuiver et al. 1998) developed for one reservoir (primary reservoir) to CRA’s from another (secondary reservoir). The usual approach has been to define the activity of the secondary reservoir as some form of constant offset (with error) from the primary reservoir (e.g. Stuiver and Braziunas 1993). In this case CRA’s from a secondary reservoir are not independent. However, the standard procedure for incorporating offset error into calibrated distributions assumes that the CRA’s from secondary reservoirs are independent (e.g. Stuiver and Reimer 1993), accordingly the calibrated distributions are incorrect. In many cases this calculation error will be insignificant, however the calculation error will be significant in some situations and approaches such as sample based Bayesian inference need to be adopted if a non independent reservoir offset is applied.