Other
Scientific paper
Jan 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010m%26ps...45...21s&link_type=abstract
Meteoritics and Planetary Science, Volume 45, Issue 1, pp. 21-31.
Other
2
Scientific paper
The oxygen fugacities recorded in the nakhlites Nakhla, Yamato-000593 (Y-000593), Lafayette, and NWA998 were studied by applying the Fe,Ti-oxide oxybarometer. Oxygen fugacities obtained cluster closely around the FMQ (Fayalite-Magnetite-Quartz) buffer (NWA998=FMQ-0.8 Y-000593=FMQ-0.7 Nakhla=FMQ Lafayette=FMQ+ 0.1). The corresponding equilibration temperatures are 810°C for Nakhla and Y-000593, 780°C for Lafayette and 710°C for NWA998. All nakhlites record oxygen fugacities significantly higher and with a tighter range than those determined for Martian basalts, i.e., shergottites whose oxygen fugacities vary from FMQ-1 to FMQ-4. It has been known for some time that nakhlites are different from other Martian meteorites in chemistry, mineralogy, and crystallization age. The present study adds oxygen fugacity to this list of differences. The comparatively large variation in fO2 recorded by shergottites was interpreted by Herd et al. (2002) as reflecting variable degrees of contamination with crustal fluids that would also carry a light rare earth element (REE)-enriched component. The high oxygen fugacities and the large light REE enrichment of nakhlites fit qualitatively in this model. In detail, however, it is found that the inferred contaminating phase in nakhlites must have been different from those in shergottites. This is supported by unique 182W/184W and 142Nd/144Nd ratios in nakhlites, which are distinct from other Martian meteorites. It is likely that the differences in fO2 between nakhlites and other Martian meteorites were established very early in the history of Mars. Parental trace element rich and trace element poor regions (reservoirs) of Mars mantle (Brandon et al. 2000) must have been kept isolated throughout Martian history. Our results further show significant differences in closure temperature among the different nakhlites. The observed range in equilibration temperatures together with similar fO2 values is attributable to crystallization of nakhlites in the same cumulate pile or lava layer at different burial depths from 0.5 to 30m below the Martian surface in agreement with Mikouchi et al. (2003) and is further confirmed by similar crystallization ages of about 1.3Ga ago (e.g., Misawa et al. 2003).
Brenker Frank E.
El Goresy Ahmed
Palme Herbert
Szymanski Anja
No associations
LandOfFree
High oxidation state during formation of Martian nakhlites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with High oxidation state during formation of Martian nakhlites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High oxidation state during formation of Martian nakhlites will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1601026