1,3,3,- 1Department of Environmental Science, School of Science, Auckland University of Technology, 55 Wellesley Street East, Auckland Central, Auckland, 1001.
- 2AstrobiologyOU, The Open University, Milton Keynes, UK. MK76AA
- 3School of Geographical and Earth Sciences, Glasgow University, Molema Building, Glasgow, UK. G128QQ
- 4NASA GSFC, Greenbelk, MD 20771
- 5CRESST II, Greenbelt, MD 20771
- 6University of Maryland, College Park, MD 20732
- 7Department of Physics and Astronomy, Howard University, Washington DC, USA
- 8School of Earth and Environmental Sciences, University of St Andrews, Irvine Building, North Street, Fife, UK, KY16 9AL
Salt minerals precipitated during evaporation or freezing of brines can capture organic and geochemical biosignatures, preserving crucial information about the aqueous environment at the time of their formation [1]. Such salts are prevalent throughout the Solar System, including Mars, icy moons, and asteroids. Their association with liquid water environments make salts high priority astrobiology targets [2].
We analysed the lipid fraction preserved within the contemporary Lost Hammer salt deposit (Canadian High Arctic) - an analogue to extraterrestrial salt systems - and paired this with space mission-relevant evolved gas analysis. Our findings show microbial organic matter (fatty acids and n-alkanes) is incorporated into Lost Hammer salts, which comprise polyhydrated sulfates and chlorides. We find a difference in the relative abundance of fatty acids vs. n-alkanes indicating how these biosignatures evolve across active and non-active parts of the spring. We also find differences between pristine salt-organic mixtures and deposits that may have been remobilised by subsequent dissolution and recrystallisation. In this system, n-alkanes have the highest preservation potential, surviving the likely dissolution and recrystallisation of hydrated salt phases. This is important for considering the fate of organic matter on icy moons such as Europa, where salts emplaced on the surface by briny extrusions may have undergone fractional crystallisation, or where subsurface salts are remobilised by localised melting. It is also relevant for once active brine systems on Mars, where cycles of groundwater recharge and/or deliquescence led to dissolution and re-precipitation of evaporitic salts.
- Schopf, J. W., Farmer, J. D., Foster, I. S., Kudryavtsev, A. B., Gallardo, V. A., & Espinoza, C. (2012). Gypsum-permineralized microfossils and their relevance to the search for life on Mars. Astrobiology, 12(7), 619-633.
Phillips, M. S., McInenly, M., Hofmann, M. H., Hinman, N. W., Warren-Rhodes, K., Rivera-Valentín, E. G., & Cabrol, N. A. (2023). Salt constructs in paleo-lake basins as high-priority astrobiology targets. Remote Sensing, 15(2), 314.
How to cite: Moreras Marti, A., Fox-Powell, M., Toney, J., McAdam, A. C., Slaymark, C., Knudson, C. A., Lewis, J. M. T., Salik, M. A., and Cousins, C. R.: Molecular biosignatures in planetary analogue salts: implications for transport of organics in sulfate-rich brines beyond Earth, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-1971, https://doi.org/10.5194/epsc-dps2025-1971, 2025.
