Doctor of Philosophy
Gordon Osinski, Neil Banerjee
Springs exist in many terrestrial settings and have supported microbial communities throughout Earth’s history. There is mounting evidence for spring deposits on Mars from Noachian age to present, implying that water may be circulating in Mars’ subsurface despite current cold, arid conditions. Current datasets for most of Mars are limited to mineralogy via orbital spectroscopy and geomorphology from visual imagery and laser altimetry. Much is known about terrestrial spring morphology, but few springs exist in Mars analogue settings, and of those, few have been investigated for mineralogy. This study reports on two sets of cold spring sites in the Canadian arctic where permafrost, frigid temperatures, and arid conditions approximate Mars’ environment. The first are acidic cold seeps forming the jarosite-rich Golden Deposit (GD) in Northwest Territories, Canada. The second are perennial saline spring systems associated with three gypsum/anhydrite diapirs on Axel Heiberg Island, Nunavut, Canada: Wolf spring (WS; also known as Lost Hammer), Colour Peak (CP), and Gypsum Hill (GH) springs. Reflectance spectra were collected to determine how similar spring deposits would appear from Mars orbit, and compared to X-ray diffraction (XRD) and inductively coupled plasma emission spectrometry (ICP-ES) results. Spectrally, GD appears to consist only of jarosite, but XRD analysis also detected natrojarosite, hydronium jarosite, goethite, quartz, clays, and hematite. In samples from WS gypsum and mirabilite are spectrally visible via strong features in the ranges of all current Mars orbital datasets, owing to their hydrated states. Halite and thenardite are spectrally detectable, but the strongest absorption features lay outside the ranges of the highest resolution Mars datasets. XRD analysis of WS samples detected primarily halite, thenardite, gypsum, and mirabilite, with other sulfates and elemental sulfur. Results from this study are applied in the search for potential spring sites on Mars, and an ovoid jarosite-rich deposit in Mawrth Vallis is proposed as a landing site for future Mars missions. Jarosite, gypsum, and thenardite facilitate preservation of organic material, and thus suspected spring deposits containing these sulfate minerals are excellent candidates in the search for evidence of life on Mars.
Battler, Melissa M., "Arctic cold spring mineralogy as an indicator of spring deposits, water, and habitable environments on Mars" (2012). Electronic Thesis and Dissertation Repository. 1080.