The study of sulfur isotopes on Mars provides crucial insights into the planet’s formation, differentiation, and volatile evolution. Primordial sulfur isotope compositions help distinguish Martian sulfur sources, including core-mantle interactions, magmatic outgassing, and atmospheric cycling. While bulk analyses have shown limited mass-independent fractionation (MIF-S), the mechanisms introducing MIF-S into Martian magmas remain poorly understood. Using in situ secondary ion mass spectrometry (SIMS), we analysed sulfides in four shergottites: Yamato 980459, Tissint, Gadamis 001, and NWA 11300, and found extreme heterogeneity in Δ³³S (–1.3 ± 0.48‰ to +1.42 ± 0.64‰) and δ³⁴S (–3.5 ± 0.11‰ to +0.73 ± 0.15‰). Large Δ³³S anomalies are observed in both depleted and enriched samples, indicating that MIF-S sulfur was incorporated into Martian magmatic systems through prolonged mantle-atmosphere exchange. This exchange likely began during magma ocean crystallisation and continued into later magmatic stages through ingassing, crustal assimilation, and/or recycling of crustal sulfur. In situ S isotope analyses of Martian shergottites reveal extreme Δ³³S heterogeneity at the mineral scale, indicating that mass-independent S signatures were incorporated into the mantle early via atmosphere–mantle exchange during magma ocean evolution
Patil et al. (Thu,) studied this question.