Chemically striking regions on Mars and Stealth revisited

• Published in: Journal of Geophysical Research. B. Solid Earth Vol. 114; no. E12
• Main Authors: Karunatillake, Suniti, Wray, James J., Squyres, Steven W., Taylor, G. Jeffrey, Gasnault, Olivier, McLennan, Scott M., Boynton, William, El Maarry, M. R., Dohm, James M.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.12.2009; American Geophysical Union
• Subjects: chemically striking regions; Dust; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fog; Gamma rays; Low temperature; Mars; Planetology; Planets; Radar; Remote sensing; Scientific apparatus & instruments; stealth; Sulfates; Volcanoes; gamma rays; global; air; Snowfall; sulfates; Earth; Mars; brines; acids; ground ice; dust; MRO space probe; Fog; exploration; salt; Regional scope; volcanoes; transport; low temperature; chemically precipitated rocks; evaporites; in situ; sedimentary rocks; depth; Radar observation; chemical composition; radar methods
• ISSN: 0148-0227; 2169-9097; 2156-2202; 2169-9100
• DOI: 10.1029/2008JE003303

The Mars Odyssey Gamma Ray Spectrometer Suite has yielded global chemical information for Mars. In this work, we establish regions of unusual chemical composition relative to average Mars primarily on the basis of Ca, Cl, Fe, H, K, Si, and Th. Using data from Mars Odyssey; the Mars Exploration Rovers; the Mars Reconnaissance Orbiter Imaging; and 3.5 cm and 1.35 cm radar observations from Earth, we examine a chemically striking ≈2.E6 km2 region and find it to overlap significantly with a radar Stealth region on Mars. It is remarkably enriched in Cl and depleted in Fe and Si (along with minor variations in H, K, and Th) relative to average Mars. Surface dust observed at the two rover sites mixed with and indurated by Ca/Mg‐bearing sulfate salts would be a reasonable chemical and physical analog to meter‐scale depths. We describe potential scenarios that may have contributed to the unique properties of this region. The bulk dust component may be an air fall deposit of compositionally uniform dust as observed in situ. Hydrothermal acid fog reactions on the flanks of nearby volcanoes may have generated sulfates with subsequent deflation and transport. Alternatively, sulfates may have been produced by low‐temperature, regional‐scale activity of ground ice–driven brine and/or regional‐scale deposition of acidified H2O snowfall.