New Mexico Geological Society Annual Spring Meeting — Abstracts

The Quebradas area, near Socorro, New Mexico, contains Paleozoic evaporite deposits, including massive gypsum in the Yeso and Atrasado Formations, which are accessible and abundant, providing a potential setting to study minerals that could serve as depositional analogs for sulfates found on Mars. In September of 2023, teams from NASA’s Goddard Space Flight Center (GSFC) and Johnson Space Center sampled gypsum from the Yeso Formation, which was then analyzed for bulk mineralogy and organic preservation during an internship at GSFC over the summer of 2024. While small amounts of carbon were detected in some samples, it was not definitively clear whether this carbon was from an organic or mineral source (Carbonneau et al., 2025). We suspect that carbon found in Quebradas gypsum is likely from mineral sources rather than preserved organics, but that organic carbon would be found in higher abundance in associated clays. If this hypothesis is correct, sulfates may not be suitable targets for assessing organic preservation on Mars, but additional information is needed about the nature and occurrence of carbon in these and other analog sediments. Here, we further these efforts by constraining the mineralogy and depositional environments of sulfate minerals in the Quebradas by additional sampling from the Yeso and Atrasado Formations, as well as more recent lacustrine deposits from the central Rio Grande rift. Bulk mineralogy was determined by powder X-ray diffraction (pXRD) and thin section petrography, and depositional environment was constrained by stable sulfur isotope analysis. pXRD analyses of Quebradas samples found minor calcite, while similar analyses of Rio Grande rift samples found no carbon-containing minerals. Calcite was not observed in thin section. This result indicates that the carbon content of Quebradas samples collected in 2023 by teams from NASA may be influenced by mineral sources rather than residual organics. δ34S values of the Quebradas sulfates range from -3.5 to +17.6‰, while δ34S values of the younger rift sulfates range from +3.8 to +6.5‰, showing values overall consistent with an evaporitic depositional environment, although with some variability that could be due to differences in specific depositional or diagenetic conditions. This additional information will help contextualize the samples as they are analyzed for organics. Although it seems likely that the bulk sulfates have very little, if any, preserved organics, ongoing analyses will continue to explore other sulfate-associated minerals and evaluate spatial associations among geochemical, mineralogical, and depositional signatures in the older and younger sulfates.

References:

1. Carbonneau, L.E., Hashberger, K.R., Pharris, G., Graham, H.V., Stern, J.C., McAdam, A.C., Bates, S., and Theiling, B.P., 2025, Total Carbon Analyses of Martian Analog Gypsum From the Quebradas Area, New Mexico, in Socorro, NM, USA, New Mexico Geological Society, https://nmgs.nmt.edu/meeting/abstracts/view.cfm?aid=3103 (accessed March 2026).