Characterization Of Ferric Hydroxysulfate On Mars And Implications Of The Geochemical Environment Supporting Its Formation
Sulfate minerals are significant components of the martian surface and provide clues about the martian geochemical environment.
One unusual Fe-sulfate phase has been intriguing Mars scientists for over a decade due to its unique spectral bands that are distinct from any known minerals and its occurrence in layered sedimentary rocks. We describe here detection of ferric hydroxysulfate (Fe3+SO4OH) and its implications for the geochemical history of Mars.
Crystalline ferric hydroxysulfate is formed by heating hydrous Fe2+ sulfates to 100 °C or above and has a strong spectral band at 2.236 µm, similar to the spectral feature observed on Mars at Aram Chaos and on the plateau above Juventae Chasma.
Hydrated sulfates at these locations likely formed through evaporative processes or low-temperature alteration.
In contrast, Fe3+SO4OH is more consistent with heating and oxidation of hydrated ferrous sulfates, potentially through deposition of lava, ash, or through hydrothermal processes.
a Mars Orbital LASER Altimeter (MOLA) map of equatorial Mars with black boxes indicating locations of the Juventae Plateau and Aram Chaos (red indicates higher elevations and blue lower elevations). b View of the plateau above Juventae Chasma with compositional units from CRISM image FRT00005814 showing pyroxene-bearing basalt in green, polyhydrated sulfates in blue, and the Fe3+SO4OH-bearing phase in red over a High-Resolution Stereo Camera (HRSC) Digital Terrain Model (DTM). c Same CRISM compositional units over a HiRISE DTM (5x vertical exaggeration) with the basalt units split into basalt-1 in dark cyan and basalt-2 in medium green, scale bar for foreground. d CRISM spectra of unusual units with a band near 2.23 µm (top) and lab spectra of several minerals (bottom). Note that none of these minerals are a good spectral match to the CRISM spectra of the Fe3+SO4OH-bearing outcrop. — Nature via PubMed
Characterization of ferric hydroxysulfate on Mars and implications of the geochemical environment supporting its formation, Nature via PubMed
Characterization of ferric hydroxysulfate on Mars and implications of the geochemical environment supporting its formation, Nature (open access)
Astrobiology
