Partitioning of Eu between augite and a highly spiked martian basalt composition as a function of oxygen fugacity (IW-1 to QFM): Determination of Eu[superscript 2+]/Eu[superscript 3+] ratios by XANES

Journal Article · Tue Mar 16 04:00:00 EDT 2010 · Am. Mineral.

DOI:https://doi.org/10.2138/am.2010.3394· OSTI ID:1002264

Karner, J M; Papike, J J; Sutton, S R; Burger, P V; Shearer, C K; Le, L; Newville, M; Choi, Y ^[1]

---

1. UNM

We have determined D{sub Eu} between augite and melt in samples that crystallized from a highly spiked martian basalt composition at four f{sub O{sub 2}} conditions. D{sub Eu} augite/melt shows a steady increase with f{sub O{sub 2}} from 0.086 at IW-1 to 0.274 at IW+3.5. This increase is because Eu{sup 3+} is more compatible than Eu{sup 2+} in the pyroxene structure; thus increasing f{sub O{sub 2}} leads to greater Eu{sup 3+}/Eu{sup 2+} in the melt and more Eu (total) can partition into the crystallizing pyroxene. This interpretation is supported by direct determinations of Eu valence state by XANES, which show a steady increase of Eu{sup 3+}/Eu{sup 2+} with increasing f{sub O{sub 2}} in both pyroxene (0.38 to 14.6) and glass (0.20 to 12.6) in the samples. Also, pyroxene Eu{sup 3+}/Eu{sup 2+} is higher than that of adjacent glass in all the samples, which verifies that Eu{sup 3+} is more compatible than Eu{sup 2+} in the pyroxene structure. Combining partitioning data with XANES data allows for the calculation of specific valence state D-values for augite/melt where D{sub Eu{sup 3+}} = 0.28 and D{sub Eu{sup 2+}} = 0.07.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1002264
• Journal Information: Am. Mineral., Journal Name: Am. Mineral. Journal Issue: (2-3) ; 02, 2010 Vol. 95; ISSN AMMIAY; ISSN 0003-004X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

58 GEOSCIENCES
BASALT
GLASS
OXYGEN
SILICATE MINERALS
VALENCE