Endogenous, yet Exotic, Sulfur in the Lunar Mantle

Abstract In situ sulfur isotope analyses of sulfides found in regolith particles from the recently opened Apollo 17 drive tube 73001/2 reveal variable 34 S/ 32 S and 33 S/ 32 S that range from that of typical lunar basalts to strongly 34 S‐ and 33 S‐depleted values (δ 34 S = −4.1 ± 0.35 to +1.5 ± 0.029; Δ 33 S = −2.8 ± 0.48 to −0.1 ± 0.27 (2σ)). All Δ 33 S and δ 34 S data are positively correlated. The correlation indicates mixing between at least two distinct sources of sulfur in the lunar mantle, one of which is associated with photochemically processed sulfur from a gaseous environment (strongly negative Δ 33 S). The gaseous precursor and its preservation in endogenous sulfides require that either the sulfur was delivered to the lunar mantle early in its history through unknown processes or it is a remnant of the giant Moon‐forming impactor.