Publication Date:
2014-10-31
Description:
The evidence for sulfate-bearing strata, across Late-Noachian to Amazonian eons, suggests a central role for sulfates in acidity and salinity of martian paleo-fluids and the planet's habitability. However, details remain unclear owing to shallow sampling and the limited ability of visible/near-infrared spectroscopy to distinguish among some sulfates. Using chemical data from the Mars Odyssey GRS, including the sulfur map of Mars, we confirm the possibility of hydrous sulfates acting as key hydrates throughout the Southern mid-latitudinal soil at decimeter depths. An H 2 O : S molar ratio between 2.4 and 4.0 for 80% of the midlatitudes is also consistent with hydrous sulfate phases, including the many Fe-sulfates hydrated in this range, or mixtures of Ca- and Mg- sulfates. Nevertheless, hydrous Fe-sulfates could explain our observations in a simpler manner relative to Ca-/Mg- mixtures. Furthermore, phyllosilicates, zeolites, amorphous phases, and H 2 O(s) do not seem strong candidates to explain the H-S variations. Consequently, we speculate that sulfates, as the primary contributor of H 2 O in bulk soil, may influence modern aqueous processes including warm-season slope lineae in the Southern hemisphere.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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