The origin, evolution, and cycling of volatiles on the Moon are established by processes such as the giant moon forming impact, degassing of the lunar magma ocean, degassing during surface eruptions, and lunar surface gardening events. These processes typically induce mass-dependent stable isotope fractionations. Mass-independent fractionation of stable isotopes has yet to be demonstrated during events that release large volumes of gas on the moon and establish transient lunar atmospheres. We present quadruple sulfur isotope compositions of orange and black glass beads from drive tube 74002/1. The sulfur isotope and concentration data collected on the orange and black glasses confirm a role for magmatic sulfur loss during eruption. The Delta S-33 value of the orange glasses is homogenous (Delta S-33 = -0.029 parts per thousand +/- 0.004 parts per thousand, 2SE) and different from the isotopic composition of lunar basalts (Delta S-33 = 0.002 parts per thousand +/- 0.004 parts per thousand, 2SE). We link the negative Delta S-33 composition of the orange glasses to an anomalous sulfur source in the lunar mantle. The nature of this anomalous sulfur source remains unknown and is either linked to (a) an impactor that delivered anomalous sulfur after late accretion, (b) sulfur that was photochemically processed early during lunar evolution and was transported to the lunar mantle, or (c) a primitive sulfur component that survived mantle mixing. The examined black glass preserves a mass-dependent Delta S-33 composition (-0.008 parts per thousand +/- 0.006 parts per thousand, 2SE). The orange and black glasses are considered genetically related, but the discrepancy in Delta S-33 composition among the two samples calls their relationship into question.

We compare the stable isotope compositions of Zn, S, and Cl for Apollo mare basalts to better constrain the sources and timescales of lunar volatile loss. Mare basalts have broadly elevated yet limited ranges in delta Zn-66, delta S-34, and delta Cl-37(SBC+WSC) values of 1.27 +/- 0.71, 0.55 +/- 0.18, and 4.1 +/- 4.0 parts per thousand, respectively, compared to the silicate Earth at 0.15, -1.28, and 0 parts per thousand, respectively. We find that the Zn, S, and Cl isotope compositions are similar between the low- and high-Ti mare basalts, providing evidence of a geochemical signature in the mare basalt source region that is inherited from lunar formation and magma ocean crystallization. The uniformity of these compositions implies mixing following mantle overturn, as well as minimal changes associated with subsequent mare magmatism. Degassing of mare magmas and lavas did not contribute to the large variations in Zn, S, and Cl isotope compositions found in some lunar materials (i.e., 15 parts per thousand in delta Zn-66, 60 parts per thousand in delta S-34, and 30 parts per thousand in delta Cl-37). This reflects magma sources that experienced minimal volatile loss due to high confining pressures that generally exceeded their equilibrium saturation pressures. Alternatively, these data indicate effective isotopic fractionation factors were near unity. Our observations of S isotope compositions in mare basalts contrast to those for picritic glasses (Saal and Hauri 2021), which vary widely in S isotope compositions from -14.0 to 1.3 parts per thousand, explained by extensive degassing of picritic magmas under high-P/P-Sat values (>0.9) during pyroclastic eruptions. The difference in the isotope compositions of picritic glass beads and mare basalts may result from differences in effusive (mare) and explosive (picritic) eruption styles, wherein the high-gas contents necessary for magma fragmentation would result in large effective isotopic fractionation factors during degassing of picritic magmas. Additionally, in highly vesiculated basalts, the delta S-34 and delta Cl-37 values of apatite grains are higher and more variable than the corresponding bulk-rock values. The large isotopic range in the vesiculated samples is explained by late-stage low-pressure vacuum degassing (P/P-Sat similar to 0) of mare lavas wherein vesicle formation and apatite crystallization took place post-eruption. Bulk-rock mare basalts were seemingly unaffected by vacuum degassing. Degassing of mare lavas only became important in the final stages of crystallization recorded in apatite-potentially facilitated by cracks/fractures in the crystallizing flow. We conclude that samples with wide-ranging volatile element isotope compositions are likely explained by localized processes, which do not represent the bulk Moon.