“An alternative perspective on the nature of sulfur isotopic variability measured in Chang'e 5 glass beads”

Using in-situ sulfur isotope measurements of glass beads from a Chang’e 5 lunar soil, Wang et al. (2024) argue that volcanism on the moon persisted until 120 Ma. This study critically evaluates their argument using current knowledge of in-situ measurement practices and the existing literature on S-isotope fraction mechanisms. This study argues that the sulfur isotope data used as a mechanism for identifying impact glass beads versus volcanic glass beads was collected and interpreted improperly, while further failing to consider plausible alternative hypotheses. The largest fractionations in the “impact” glass beads could represent mixing with background sulfur in the instrument rather than S loss during impacts. The fractionation among the “volcanic” glass beads may be an issue of instrumental mass fractionation corrections from improper standardization or a previously unidentified lunar sulfur reservoir, rather than S loss during lunar volcanism. • Volcanic glass beads in CE’5 soil may be misclassified • S isotope data in “volcanic” beads may reflect improper IMF corrections • The S isotope data in impact beads may be influenced by background contamination • 120 Ma volcanism on the moon is difficult to reconcile using S isotopes