Description
- Abstract:
- Sulfates are important secondary minerals produced from the evaporation of fluids involved in the aqueous alteration of Mars' primary lithology [Tosca et al. 2005]. Sulfates are potentially good tracers of past environment, and the presence, abundance, and formation processes of sulfates on the surface can all characterize how much water was available. The Valles Marineris canyon system contains many large sulfate deposits. A recent mineralogic model posits that Mars had three eras of alteration mineral formation as the planet cooled and water was increasing unavailable ? Phyllosian, Theiikian, and Siderikian [Bibring et al. 2005]. These eras of phyllosilicate, sulfate, and anhydrous iron oxide formation were hypothesized based on OMEGA (Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activite) spectral data. This thesis uses higher resolution spectral and imaging data from the Mars Reconnaissance Orbiter, and especially the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument to test that model. The theses is broken into three topics: (1) the stability of sulfates to alteration under current Martian conditions and how much sulfate hydration state reflects recent periods of high obliquity; (2) the stratigraphic relationship of sulfates and ferric oxides in Valles Marineris and the possible low temperature diagenetic process that formed them; and (3) detailed local and regional stratigraphy of sulfates and other alteration minerals in Valles Marineris. This mapping in Ius Chasma showed phyllosilicate alteration of the Noachian basement predated sulfate deposition. Alteration minerals in Valles Marineris range from other precipitated at low pH (jarosite) to intermediate pH (poorly crystalline hydrated silicate ? liekly a sulfate/smectite mixture) to high pH (smectites). These phases are found in adjacent outcrops, indicating water was available in isolated areas and that Mars retains its early geochemical history. Additionally, the thesis presents mapping of all sulfate deposits in Valles Marineris detected with OMEGA and CRISM spectral data. Terrestrial and martian sulfate deposits are compared to see what these sulfates can tell us about the aqueous evolution of Mars.
- Notes:
- Thesis (Ph.D.) -- Brown University (2009)
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Citation
Roach, Leah H.,
"Sulfates in Valles Marineris as Indicators of the Aqueous Evolution of Mars"
(2009).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0FX77QC
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....