44-7 NIR and Raman Spectroscopy Reveal Sulfate Seasonality in British Columbia Basque Lakes, Analogues to “Cold and Wet” and “Warm and Wet” Mars

Session: Advancing Mineral Science and Exploring Planetary Surfaces: In Honor of MSA Dana Medalist, Elizabeth B. Rampe, Part II

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Mg-sulfate rich lakes were once present on early Mars. Such lakes might have been habitable, with available solvent and chemical gradients. Salt precipitates from saline lakes on Mars may also preserve information about the climates in which they were present (e.g., temperature, atmospheric composition, and organic preservation). Here we investigate links between climate and mineralogy/geochemistry of Mg-sulfate lakes through study of the Basque Lakes in British Columbia, Canada. The Basque Lakes are a series of closed-basin Mg-Na-SO₄ lakes that evaporate in the summer and fall, and freeze over in the winter, leading to variable mineralogical assemblages that change with climate. We visited the Basque Lakes over 6 different field seasons (3 in the fall, 3 in the winter), determining that mineralogy indeed changes seasonally, and such changes are detectable using the rover-relevant instrumentation of near-infrared (NIR) spectroscopy and Raman spectroscopy. We identify the double salt konyaite (Na₂Mg(SO₄)₂•5H₂O) in the fall outside of its expected stability range, as well as other metastable minerals forming in efflorescent crusts. Meanwhile, a possible metastable Na-sulfate heptahydrate (Na₂SO₄•7H₂O), mirabilite (Na₂SO₄•10H₂O), and meridianiite (MgSO₄•11H₂O) form in salt pools in the winter. These results suggest that metastable salt mixtures may also form from martian paleolakes connected to an atmosphere. Spectroscopic results reveal that warm-temperature salts should be detectable on Mars particularly with in situ Raman and NIR, but that the lack of their detection thus far on Mars may be linked to a low preservation potential of efflorescent crusts. Highly hydrated salts can be used as cold-climate indicators and are detectable with Mars-relevant instruments, but may transform to lower hydrates under dry Mars conditions, possibly leaving traces in the form of pseudomorphs and crystal molds. In summation we find that in a fluctuating climate, salt assemblages do not settle into equilibrium phases, such that metastable minerals may have precipitated widely on Mars from early lakes. Additionally, variability related to climate, particularly through the cryo-precipitation of highly hydrated crystalline salts in brine pools, could produce observables detectable via Mars-relevant spectroscopic techniques. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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