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Metal-saturated sulfide assemblages in NWA 2737: Evidence for impact-related sulfur devolatilization in Martian meteorites
- Source :
- Meteoritics and Planetary Science, Meteoritics and Planetary Science, Wiley, 2012, 47 (11), pp.1830-1841. ⟨10.1111/maps.12015⟩
- Publication Year :
- 2012
- Publisher :
- HAL CCSD, 2012.
-
Abstract
- International audience; NWA 2737, a Martian meteorite from the Chassignite subclass, contains minute amounts (0.010 ± 0.005 vol%) of metal-saturated Fe-Ni sulfides. These latter bear evidence of the strong shock effects documented by abundant Fe nanoparticles and planar defects in Northwest Africa (NWA) 2737 olivine. A Ni-poor troilite (Fe/S = 1.0 ± 0.01), sometimes Cr-bearing (up to 1 wt%), coexists with micrometer-sized taenite/tetrataenite-type native Ni-Fe alloys (Ni/Fe = 1) and Fe-Os-Ir-(Ru) alloys a few hundreds of nanometers across. The troilite has exsolved flame-like pentlandite (Fe/Fe + Ni = 0.5-0.6). Chalcopyrite is almost lacking, and no pyrite has been found. As a hot desert find, NWA 2737 shows astonishingly fresh sulfides. The composition of troilite coexisting with Ni-Fe alloys is completely at odds with Chassigny and Nahkla sulfides (pyrite + metal-deficient monoclinic-type pyrrhotite). It indicates strongly reducing crystallization conditions (close to IW), several log units below the fO2 conditions inferred from chromites compositions and accepted for Chassignites (FMQ-1 log unit). It is proposed that reduction in sulfides into base and precious metal alloys is operated via sulfur degassing, which is supported by the highly resorbed and denticulated shape of sulfide blebs and their spongy textures. Shock-related S degassing may be responsible for considerable damages in magmatic sulfide structures and sulfide assemblages, with concomitant loss of magnetic properties as documented in some other Martian meteorites.
- Subjects :
- 010504 meteorology & atmospheric sciences
Sulfide
Pentlandite
[SDE.MCG]Environmental Sciences/Global Changes
Geochemistry
Mineralogy
engineering.material
010502 geochemistry & geophysics
01 natural sciences
[SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Pyrrhotite
0105 earth and related environmental sciences
chemistry.chemical_classification
Chalcopyrite
Taenite
Troilite
Geophysics
chemistry
Meteorite
Space and Planetary Science
visual_art
engineering
visual_art.visual_art_medium
Pyrite
Geology
Subjects
Details
- Language :
- English
- ISSN :
- 10869379 and 19455100
- Database :
- OpenAIRE
- Journal :
- Meteoritics and Planetary Science, Meteoritics and Planetary Science, Wiley, 2012, 47 (11), pp.1830-1841. ⟨10.1111/maps.12015⟩
- Accession number :
- edsair.doi.dedup.....dc6ca6653a98c24c3edf14417c002c49