The ⁴⁰ K ‐K dating system: 1. Improving data interpretation using new model calculations

The 40 K‐K cosmic‐ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic 40 K with the stable cosmogenic isotopes 39 K and 41 K. However, earlier applications relied on semi‐empirical production models and inconsistent analytical data sets, limiting their reliability. This study presents a comprehensive reassessment of the 40 K‐K and 4 He/ 21 Ne system using state‐of‐the‐art model calculations. Production rates of 39 K, 40 K, and 41 K were simulated with the GEANT4–INCL++6 framework, incorporating updated excitation functions and fully considering depth‐dependent shielding effects. The resulting model yields physically robust relationships between K isotopes and noble gas shielding proxies, such as 4 He/ 21 Ne. In addition to revisiting the classical approach used by Voshage and co‐workers, we introduce two new alternative strategies for calculating CRE ages: a two‐component mixing model and a native‐K correction approach that mitigates contamination effects. Overall, these developments establish a more accurate and physically consistent framework for future applications of the 40 K–K system in cosmochemistry and studies of galactic cosmic rays.