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Ree in Shergottite Augites and Whole RocksRedox variations have been reported among the shergottites. Eu and Gd partitioning experiments designed for the LEW86010 angrite, to infer a range of fo2 for the shergottites have been used. Fo2 using equilibria between Fe-Ti oxides have been inferred. There is fairly good agreement between the Fe-Ti oxide determinations and the estimates from Eu anomalies in terms of which meteorites are more or less oxidized. The Eu anomaly technique and the Fe-Ti oxide technique both essentially show the same trend, with Shergotty and Zagami being the most oxidized and QUE94201 and DaG 476 being the most reduced. Thus, the variation in fo2 appears to be both real and substantive. However, although the redox trends indicated by the two techniques are similar, there is as much as a two log unit offset between the results. One explanation for this offset is that the Eu calibration used for the shergottites was actually designed for the LEW86010 angrite, a silica-undersaturated basalt whose pyroxene (diopside) compositions are rather extreme. To correct this, a set of experiments on the redox relationship of Eu partitioning relative to Sm and Gd for pyroxene and melt compositions more relevant to Martian meteorites were conducted. We have taken the experimentally determined relationship between D (sup Augite/melt) (Sm,Eu,Gd) and fO2 and applied it to augite Eu and Gd data for the basaltic Shergottites of as well as previously unreported augite Sm data.
Document ID
20020090127
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Musselwhite, D. S.
(NASA Johnson Space Center Houston, TX United States)
Wadhwa, M.
(Field Museum of Natural History Chicago, IL United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of the Martian Meteorites
Subject Category
Lunar And Planetary Science And Exploration
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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