A combined electron microprobe (EMP) and Raman spectroscopic study of the alteration products in Martian meteorite MIL 03346

摘要: [1] We examine the secondary alteration products in MIL 03346 using Raman spectroscopic and electron microprobe traverses. Discussion focuses on single olivine ,177 supplemented with observations from ,168 ,169. Traverses start at rim progress into interior. Dark brown, nearly opaque, laihunite [Fe2+Fe3+2(SiO4)2] is present as overgrowths, 20–50 µm veins of reddish-brown stilpnomelane [(K,Na,Ca)4(Ti0.1,Al2.3,Fe3+35.5,Mn0.8,Mg9.3) (Si63Al9)(O,OH)206∗n(H2O)] occur inside olivine. Stilpnomelane crosscuts postdates laihunite; are sharp contact host but lined by ~5 films jarosite [KFe3+3(SO4)2(OH)6] a later generation alteration. An interstitial also hosts stilpnomelane. The most recent phases gypsum bassanite our X-ray maps Ca-sulfates were not observed detected point count. All sulfates believed to be Martian. groundmass indicates rapid cooling elevated temperatures fO2 near QFM. Reports synthesis oxidation (100–800°C) suggest overgrowths formed during consolidation. In terrestrial rocks, product late diagenesis garnet-grade metamorphism. MIL, appears phase lower end this stability range, conditions akin diagenesis. spectra indicate that stilpnomelane, jarosite, hydrated. contains Cl− was followed acid alteration, deposition halide salts more neutral chloride solutions.