Inventory of H2O in the ancient Martian regolith from Northwest Africa 7034: The important role of Fe oxides. Issue 23 (4th December 2014)

• Record Type: Journal Article
• Authors: Muttik, Nele; McCubbin, Francis M.; Keller, Lindsay P.; Santos, Alison R.; McCutcheon, Whitney A.; Provencio, Paula P.; Rahman, Zia; Shearer, Charles K.; Boyce, Jeremy W.; Agee, Carl B.
• Is Part Of: Geophysical research letters. Volume 41:Issue 23(2014:Dec.)
• Page Start: 8235
• Page End: 8244
• Publication Date: 2014-12-04
• Subjects: Martian meteorites -- NWA 7034 -- ancient Martian regolith breccia -- water in NWA 7034 -- hydrous phases; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2014GL062533
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Water‐rich Martian regolith breccia Northwest Africa (NWA) 7034 was analyzed by Fourier transform infrared spectroscopy and transmission electron microscopy to determine the inventory and phase distribution of H2 O (used herein to refer to both molecular H2 O and OH − structural components in hydrous minerals). Hydrous Fe oxide phases (hydromaghemite and an unidentified nanocrystalline Fe‐bearing oxide phase observed with hydromaghemite) and phyllosilicates (saponite) were identified as the primary mineralogic hosts for H2 O with a minor contribution from Cl‐rich apatite. Based on mass balance calculations and modal abundances of minerals constrained by powder X‐ray diffraction and petrography, we can account for the entire 6000 ppm H2 O measured in bulk rock analyses of NWA 7034. This H2 O is distributed evenly between hydrous Fe‐rich oxides and phyllosilicates, indicating that Fe oxides could be as important as phyllosilicates for H2 O storage in Martian surface material. Key Points: H2 O in NWA 7034 is hosted by Fe oxyhydroxides, phyllosilicates, and phosphates H2 O is evenly distributed between hydrous Fe oxides and phyllosilicates Fe oxide/hydroxides could be important hosts for water on the Martian surface