ArAR - A software tool to promote the robust comparison of K-Ar and 40Ar/39Ar dates published using different decay, isotopic, and monitor-age parameters

- Changes in physical parameters cause discrepancies among K-Ar and 40Ar/39Ar datasets.
- Changes in calibration standards affect both 40Ar/39Ar monitors and unknown samples.
- We describe how to account for such changes, and provide recalculation equations.
- The free ArAR software facilitates recalculating K-Ar and 40Ar/39Ar dates.

The comparison of K-Ar and 40Ar/39Ar geochronologic data published by different laboratories is markedly hindered by the inconsistent use of the parameters necessary to convert isotopic analyses to dates. This problem is particularly acute when we try to evaluate the significance of datasets obtained prior to the development of community consensus values for basic decay constants, isotopic abundances, and the ages of common monitor minerals. Unfortunately, the effect of using different parameters for the same dataset can sometimes exceed the quoted analytical precision of derived dates. We created the Argon Age Recalculator, or ArAR, to help researchers account for such discrepancies in a simple, efficient manner, allowing for more robust comparisons among datasets and more effective compilation of existing datasets using self-consistent parameter sets. ArAR is freely available as a platform independent executable application at: http://group18software.asu.edu.