P079-0011
Mid-IR Signatures of Transient Liquid Salty Brines in Martian Analogs

Wednesday, 16 December 2020
Poster
Merve Yesilbas, SETI Institute, Carl Sagan Center, Mountain VIEW, CA, United States; Umeå University, Chemistry, Umeå, Sweden and Janice L Bishop, SETI Institute, Mountain View, CA, United States
Abstract:
Hydrated minerals and salts on the near surface of Mars may facilitate formation of ‘transient liquid salty brines’ following the diurnal cycle on Mars, both at equatorial regions1,2 and below the south polar ice caps3. The presence of near surface liquid salty brines could have implications for the potential of life and habitability, the past and present climate, and geologic processes (e.g., Recurring Slope Linea (RSL)) on Mars, which are all components of the Mars 2020 mission. The salts may liquify the ice at near surface of Mars above their specific eutectic temperatures (e.g., -51 °C, 30 wt.% CaCl2) possibly forming through deliquescence and/or by thin water-ice films formed on minerals4.

Many studies with Cl salts have resolved their deliquescence/efflorescence properties at low temperatures5-6, however less attention has been paid to mixtures of Cl salts with minerals or martian analogs4,7, which is the focus of our study. Our study specifically probes the O-H stretching region (3000-4000 cm-1), sensitive to any O-H bond length changes in 150-175 ppm range9 to resolve the phase changes of water, ice, and brine solutions. Using cryogenic-FTIR, we collected the spectra of flash frozen pastes of Cl salt mixtures (40% CaCl2 and 10% Mg(ClO4)2) of two volcanic ash samples and the Mojave Mars Simulant (MMS) at -90 °C, then these mixtures were gradually heated at 10 °C/min up to 25 °C. Our results gave two important outcomes: (i) flash frozen pastes of each sample at -90 °C revealed distinct spectral features in relation to the salts, (ii) during the hydration process, only one of the volcanic ash samples liquefied following the phase diagram of Cl salts, the other samples liquefied at higher eutectic temperatures of Cl salts. To understand the complex relationships between Cl salts and martian analogs, continuing experiments are probing the phase changes in salty martian analogs for transient liquid salty brine formation with XRD at low temperatures.

  1. Martín-Torres et al.(2015) Nat Geosci, 8, 357-361.
  2. Fischer et al.(2014) Geophys Res Lett, 41, 4456-4462.
  3. Orosei et al.(2018) Sci, 361, 490.
  4. Primm et al.(2018) J Geophys Res Plan, 123, 2076-2088.
  5. Primm et al.(2017) Geochim Cosmochim Acta, 212, 211-220.
  6. Wang&Zhou(2014) Icarus, 234, 162-173.
  7. Yeşilbaş et. al.(2018) ACS Earth Space Chem, 2, 314-319.
  8. Ohno et al.(2005) PCCP, 7, 3005-3014.
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