Selection of Suitable Data Sets Improves ²³⁰Th/U Dates of Dirty Material

²³⁰Th/U dating of dirty material such as fen peat and secondary carbonates depends on the ability to select suitable and to discard unsuitable data sets before the calculation of ²³⁰Th/U ages. This means that open system conditions with respect to uranium during ageing are excluded and solely one source of detrital contamination was present in the samples. Three kinds of selection approaches of suitable data sets were applied: (1) isotope ratio plots, (2) the isotope-ratio evolution plot and the iterative determination of the decay-corrected initial detrital ²³⁰Th/²³²Th activity ratio (AR) as well as (3) depth profiles of the uranium concentration and the ²³⁴U/²³⁸U AR and the ash content. For reliable ²³⁰Th/U age dating of dirty material all selection procedures have to be commonly applied because none of them works perfectly.