Martian Salts and Surface Materials as Paleoclimate Indicators Through Orbital, In Situ, and Analogue Analyses

Mars—a cold, dry planet today—once was home to flowing, pooling, and concentrating liquid water. The aqueous processes that occurred billions of years ago on the surface of Mars left traces, often in the form of minerals. The composition, structure, and chemistry of these minerals records the environments in which they formed, including the temperature of fluids in an environment. Here, we investigate the paleoclimate of Mars in three distinct ways: through orbital data of a proposed ancient hydrothermal lake on Mars; in situ data of an ancient, habitable lake on Mars; and in situ study of a series of lakes on earth that serve as Mars analogues. We rely on spectroscopy—primarily, near-infrared, Raman, laser induced spectroscopy, and X-ray fluorescence—to determine the mineralogical and chemical makeup of climate indexing minerals. We find that the proposed ancient hydrothermal system on Mars (Eridania Basin) has minimal definitive surface evidence for hydrothermalism, and the mineralogy and geochemistry is more consistent with low-temperature, minimal water-to-rock weathering of basaltic materials. Our work in the Mars analogue Basque Lakes in British Columbia, Canada, reveals a suite of metastable minerals forming in brine pools and efflorescent crusts seasonally, indicating that cold-temperature salts form from freezing brines, which might act as cold-climate indicators when preserved in the rock record. Finally within Gale crater, Mars, we report on unusual geochemical signatures within dark-toned laminations in sulfate-bearing strata, suggesting that likely warm diagenetic fluids permeated bedding planes to form hydrated Na-Mg-sulfates and fluorine-bearing minerals. These fluids might be linked to major climate cycles forming the stratigraphy in this region.

Date

2025-07-10

Resource Type

Text

Resource Subtype

Dissertation

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