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Report to MEPAG

. . Why?.

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Report to MEPAG

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    1. Report to MEPAG Allan Treiman, LPI; Jim Papike, UNM; Dave Beaty, JPL

    2. Why?

    3. Where ? When ? Lunar and Planetary Institute, Houston. October 22-24, 2006. Reception and posters, Sunday Oct. 22. Topical sessions, 4 consecutive, Monday-Tuesday, Oct. 23-24.

    4. Who ? 115 Registered Attendees, 27 on-site. Many more than expected 24 Students Most from US, several from Europe ESA, Mars Express Cross-disciplinary Remote Sensing Geochemistry Planetary & Terrestrial

    5. Presentations by Discipline Mars Remote Sensing - 9 Earth Remote Sensing - 4 Mars Surface Missions - 14 Earth “Surface Missions” - 8 Geochemistry - 20 Mineralogy - 5 Martian Meteorites - 5 Other - 1 (Sample Return)

    6. Sessions Characterization of sulfate deposits on the surface of Mars from orbital data: Past, present and future. Sulfate characterization accomplished by early surface missions, by MER, and planned for Phoenix and MSL Recent advances in the study of terrestrial acid sulfate minerals Analytical, experimental, and theoretical studies of Martian-sulfate-relevant systems

    7. Mars Sulfates from Orbit Sulfates detected from many platforms OMEGA Imaging Spectrometer Valles Marineris - kieserite (MgSO4·H2O), poly-hydrated Mg sulfate, gypsum; correlated with sedimentary layers. North Polar dunes - gypsum! CRISM - First Views Will show sulfate minerals in geologic contexts!

    8. Mars Sulfates from the Surface Viking - XRF MER - APX, Mössbauer, mini-TES Phoenix TEGA - thermal evolved gases MECA - Wet Chem Lab modules Element-specific electrodes Solution chemistry over time MSL ‘09 LIBS - S analysis is challenging CheMin - X-ray diffraction, fluorescence SAM - Evolved gas / Mass spec. Viking - Ben Clark MER - Squyres, Morris Phoenix: P. Smith TEGA - Boynton MECA - Kounaves MSL - Blaney LIBS - Clegg / Weins CheMin - D. Bish SAM - MahaffeyViking - Ben Clark MER - Squyres, Morris Phoenix: P. Smith TEGA - Boynton MECA - Kounaves MSL - Blaney LIBS - Clegg / Weins CheMin - D. Bish SAM - Mahaffey

    9. Terrestrial Sulfates. I Extreme Environments Acid Mine Drainage - FeS2+O2 (Rio Tinto, Spain) Iron Mountain, CA (C.N. Alpers) Solution pH to < -3 !! Weird minerals, weird microbes. Leviathan Mine, CA (W. Calvin) S0 + O2 Volcanic fumaroles / alteration St. Lucia (J. Greenwood) Caves (P. Boston) Influence of biota ! Stable isotope constraints Impact-related (K-T) Stalactite and stalagmites of melanterite, an iron sulfate mineral [FeSO4.7H2O), containing zinc and copper. pH of drip water was -0.7. Beaker is 2 liters. alpers3_green.jpg. http://ca.water.usgs.gov/water_quality/acid/pic4.htm Snottites are slimy, dripping stalactites made of goo, that contain bacteria in abundance and beautiful microscopic gypsum crystal formations. (Photo Jim Pisarowicz). Both exist at the same time in an environment whose pH is 0.5! http://www.i-pi.com/~diana/slime/villaluz/Stalactite and stalagmites of melanterite, an iron sulfate mineral [FeSO4.7H2O), containing zinc and copper. pH of drip water was -0.7. Beaker is 2 liters. alpers3_green.jpg. http://ca.water.usgs.gov/water_quality/acid/pic4.htm Snottites are slimy, dripping stalactites made of goo, that contain bacteria in abundance and beautiful microscopic gypsum crystal formations. (Photo Jim Pisarowicz). Both exist at the same time in an environment whose pH is 0.5! http://www.i-pi.com/~diana/slime/villaluz/

    10. Terrestrial Sulfates. II Jarosite-group minerals as environmental probes Fluid composition from mineral equilibria Jarosite-Alunite (K,Na,H3O)(Fe,Al)3(SO4)2(OH)6 Crandallite (CaH)Al3(PO4)2(OH)6 Florencite (REE)Al3(PO4)2(OH)6 Fluid/gas composition from fluid inclusions Age by K/Ar (39Ar/40Ar) Stable isotopes: S, H, O, (K, Fe) Different O from sulfate, hydroxyl! Kinetics of decomposition => ? Duration of exposure to liquid water.

    11. Other Studies. I. Mg-sulfates as Environmental Probes Hydration / water activity; MgSO4·nH2O where n = 0, 1, 2, 3, 4, 5, 6, 7, 11. Rates of hydration / desiccation may constrain seasonal or long-term humidity New data on MgSO4·11H2O (R. Petersen) It + ice melt at ~-2°C Alone, it melts at 2°C to MgSO4 solution + crystals of epsomite (MgSO4·7H2O) Figure 1. Phase diagram for MgSO4-H2O system (after Hogenboom et al., 1995). Field of MgSO4.12H2O in original reference has been relabeled as MgSO4.11H2O based on this work. MgSO4.11H2O melts incongruently to epsomite and saturated solution at 2 this binary system. Figure 2. Crystals of MgSO4.11H2O in cross-polarized light. Tapered morphology of crystals is indicated by gradual reduction in birefringence toward edges of each crystal. Crystal that has incongruently melted to splay of epsomite needles and solution is visible at upper right corner. Field of view 1 mm. Fig 5. Mosaic image taken by microscopic imager on Mars Exploration Rover Opportunity showing portion of rock outcrop at Meridiani Planum, Mars, dubbed “Guadalupe.” Plate-shaped features are ~1 mm across and as long as 8 mm and have tapered edges. In other rocks nearby, molds continue into rock for at least as deep as rock abrasion tool was able to grind (~5 mm) and often increase in dimension with depth (Herkenoff et al., 2004, 2006) Field of view is 4.8 cm across. Nasa/JPL image 16-jg-02-mi1-B035R1Figure 1. Phase diagram for MgSO4-H2O system (after Hogenboom et al., 1995). Field of MgSO4.12H2O in original reference has been relabeled as MgSO4.11H2O based on this work. MgSO4.11H2O melts incongruently to epsomite and saturated solution at 2 this binary system. Figure 2. Crystals of MgSO4.11H2O in cross-polarized light. Tapered morphology of crystals is indicated by gradual reduction in birefringence toward edges of each crystal. Crystal that has incongruently melted to splay of epsomite needles and solution is visible at upper right corner. Field of view 1 mm. Fig 5. Mosaic image taken by microscopic imager on Mars Exploration Rover Opportunity showing portion of rock outcrop at Meridiani Planum, Mars, dubbed “Guadalupe.” Plate-shaped features are ~1 mm across and as long as 8 mm and have tapered edges. In other rocks nearby, molds continue into rock for at least as deep as rock abrasion tool was able to grind (~5 mm) and often increase in dimension with depth (Herkenoff et al., 2004, 2006) Field of view is 4.8 cm across. Nasa/JPL image 16-jg-02-mi1-B035R1

    12. Other Studies: II Geochemistry - Lab/theory Formation & evolution of sulfatic brines (P. King, J. Moore, J. McLennan, M. Tosca) Challenges Thermo data on sulfates, solid solutions Data and phases at low-T (G. Marion) Kinetics, esp. rxns involving Fe (P. King) Martian Meteorites Pre-terrestrial aqueous minerals from alkaline - neutral waters Sample Return Significant challenges in delivering unmodified Martian sulfates to Earth

    13. Summary Observations At least 4 classes of sulfate deposits: Mg-SO4; Ca-SO4; jarositic; & ferric sulfate (Gusev). Sulfate minerals are commonly correlated with geology/topography, implying local/regional controls on their origins. Mars’ sulfate mineralogy may change with variations in T and humidity (short- and long-term). It may be difficult to infer geologic environments only from sulfate mineralogy. After initial characterization, it may be useful to re-visit a sulfate site with specialized landed instruments (e.g., K-Ar age dating).

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