High-resolution geochronology is one of the key factors to predict volcanic eruptions. To build up a high-resolution geochronological framework, we reported 21 new high-precision eruption ages (⁴⁰Ar / ³⁹Ar) for a ~ 3.3 × 10⁶-year-old volcanic field: Milos (Greece). In combination with geochemical information and eruption volumes from the volcanoes of Milos, the long-lived volcanic history could provide important clues for the prediction of volcanic eruptions.

⁴⁰K is an isotope of potassium that undergoes several different modes of radioactive decay. We use the decay of ⁴⁰K to determine the ages of geologic materials that contain potassium but doing this requires us to know the rate at which ⁴⁰K decays by its different decay modes. Here, we investigate one decay mode of ⁴⁰K that has previously been overlooked. We demonstrate that this decay mode exists, estimate its rate, and evaluate its significance for geochronology.

We show results from a new type of ion detector technology for mass spectrometry that allows us to measure ion beams more precisely. This technology expands the range of ages we can measure using a single instrument and makes it possible to measure those ages – including all required corrections and adjustments – with more confidence. We show measurements of widely used standard materials for Ar / Ar, including air and synthetic standard gas, to illustrate the capabilities of the new detectors.