Comment on Barboni et al. (2025), ‘Pervasive impact modification of pristine lunar clasts’

Felix Boschetty, John Pernet-Fisher, Katie Joy, Romain Tartèse, Joshua Snape

In a recent contribution, Barboni et al. (2025) present an experimental calibration relating the aluminium content of zircon and its parent melt under lunar conditions. This calibration is then used to argue that lunar zircons are not in equilibrium with their host silicate melts, and that caution is required when interpreting zircon-derived U-Pb dates in evolved lunar rocks. Their contribution includes an Excel spreadsheet that allows users to calculate a predicted equilibrium melt composition for lunar zircons to test whether they are in equilibrium with their host melt. While this study addresses important questions in lunar petrology, several methodological issues limit the reliability and applicability of the current proposed model. These include (1) a mismatch between experimental and natural compositions, (2) analytical data quality, and (3) the regression approach used to derive the calibration. Here, we examine each issue and discuss its implications for the interpretation of lunar zircon petrogenesis.