Petrogenesis of augite-bearing ureilites Hughes 009 and FRO 90054/93008 inferred from melt inclusions in olivine, augite and orthopyroxene

Goodrich, C. A.; Fioretti, A. M.; Orman, James A. Van

doi:10.1016/j.gca.2009.02.018

Cited by 21 publications

(57 citation statements)

References 37 publications

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“…; Goodrich et al. ; S3), and melt inclusions in Nakhla show typical signs of such re‐equilibration: wall olivine is homogeneous, with Fe/Mg ratio identical to that of host olivine; daughter pyroxenes are likewise homogeneous, with Fe/Mg ratio very similar to that of the olivine (Treiman ); residual glasses have very low concentrations of FeO and MgO (Danyushevsky et al. ); and the average bulk inclusion composition has an Fe/Mg ratio (Table ) that is far too low to be in equilibrium with the olivine.…”

Section: Discussionmentioning

confidence: 99%

K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

Goodrich

Treiman

Filiberto

et al. 2013

Meteorit & Planetary Scien

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Abstract-We used new analytical and theoretical methods to determine the major and minor element compositions of the primary trapped liquid (PTLs) represented by melt inclusions in olivine and augite in the Martian clinopyroxenite, Nakhla, for comparison with previously proposed compositions for the Nakhla (or nakhlite) parent magma. We particularly focused on obtaining accurate K 2 O contents, and on testing whether high K 2 O contents and K 2 O/ Na 2 O ratios obtained in previous studies of melt inclusions in olivine in Nakhla could have been due to unrepresentative sampling, systematic errors arising from electron microprobe techniques, late alteration of the inclusions, and/or boundary layer effects. Based on analyses of 35 melt inclusions in olivine cores, the PTL in olivine, PTL oliv , contained (by wt) approximately 47% SiO 2 , 6.3% Al 2 O 3 , 9.6% CaO, 1.8% K 2 O, and 0.9% Na 2 O, with K 2 O/ Na 2 O = 2.0. We infer that the high K 2 O content of PTL oliv is not due to boundary layer effects and represents a real property of the melt from which the host olivine crystallized. This melt was cosaturated with olivine and augite. Its mg# is model-dependent and is constrained only to be ≥19 (equilibrium Fo = 40). Based on analyses of 91 melt inclusions in augite cores, the PTL in augite, PTL aug , contained (by wt) 53-54% SiO 2 , 7-8% Al 2 O 3 , 0.8-1.1% K 2 O, and 1.1-1.4% Na 2 O, with K 2 O/Na 2 O = 0.7-0.8. This K 2 O content and K 2 O/Na 2 O ratio are significantly higher than inferred in studies of melt inclusions in augite in Nakhla by experimental rehomogenization. PTL aug was saturated only with augite, and in equilibrium with augite cores of mg# 62. PTL aug represents the Nakhla parent magma, and does not evolve to PTL oliv by fractional crystallization. We therefore conclude that olivine cores in Nakhla (and, by extension, other nakhlites) are xenocrystic. We propose that PTL oliv and PTL aug were generated from the same source region. PTL oliv was generated first and emplaced to form olivine-rich cumulate rocks. Shortly thereafter, PTL aug was generated and ascended through these olivine-rich cumulates, incorporating fragments of wallrock that became the xenocrystic olivine cores in Nakhla. The Nakhla (nakhlite) mantle source region was pyroxenitic with some olivine, and could have become enriched in K relative to Na via metasomatism. A high degree of melting of this source produced the silica-poor, alkali-rich magma PTL oliv . Further ascension and decompression of the source led to generation of the silica-rich, relatively alkali-poor magma PTL aug . Potassium-rich magmas like those involved in the formation of the nakhlites represent an important part of the diversity of Martian igneous rocks.

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Section: Discussionmentioning

confidence: 99%

K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

Goodrich

Treiman

Filiberto

et al. 2013

Meteorit & Planetary Scien

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“…As shown by, e.g., Jaques and Green (1980), during low-pressure anatexis (up to pressures far higher than would occur within an asteroid-sized body), among the mafic silicates, pyroxene (high SiO 2 ) melts, olivine (low SiO 2 ) does not; and the balance of the melting is dominantly at the expense of feldspar (high SiO 2 ). In detail, the SiO 2 content of feldspar is proportional to Na content, which feldspathic clasts in polymict ureilites indicate was high (Ikeda et al, 2000;Ikeda and Prinz, 2001;Cohen et al, 2004;Kita et al, 2004;Goodrich et al, 2009). Although the melt has roughly 2Â lower (FeO + MgO) than the restite, the melt's FeO/MgO is much higher, so the net effect is to leave the restite's FeO little changed.…”

Section: Implications For and From Ureilite Petrologymentioning

confidence: 99%

“…EA-5 for results from models that assume partial melting was accompanied by major smelting. Data for feldspathic clasts and glasses within polymict-brecciated ureilites (two defocused-beam clast analyses, five "trapped" magmatic glass compositions, and two glass analyses from glass-dominated clasts) are from Ikeda and Prinz (2001), Kita et al (2004) and Goodrich et al (2009). Mesostasislike glasses, interstitial to larger crystalline silicate components (Ikeda et al, 2000;Kita et al, 2004) were excluded from this data set.…”

Section: Oxygen Once Againmentioning

confidence: 99%

Stable isotopes and the noncarbonaceous derivation of ureilites, in common with nearly all differentiated planetary materials

Warren

2011

Geochimica et Cosmochimica Acta

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“…2000; Mittlefehldt et al. 2005), the ureilite group has been divided into three subgroups based on pyroxene composition in Goodrich et al. (2004, 2007, 2009): olivine‐pigeonite, olivine‐orthopyroxene, and augite‐bearing.…”

Section: Introductionmentioning

confidence: 99%

Jiddat al Harasis 422: A ureilite with an extremely high degree of shock melting

Janots

Gnos

Hofmann

et al. 2011

Meteorit & Planetary Scien

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Abstract-The Jiddat al Harasis (JaH) 422 ureilite was found in the Sultanate of Oman; it is classified as a ureilitic impact melt breccia. The meteorite consists of rounded polycrystalline olivine clasts (35%), pores (8%), and microcrystalline matrix (57%). Clasts and matrix have oxygen isotopic values and chemical compositions (major and trace elements) characteristic of the ureilite group. The matrix contains olivine (Fo 83-90 ), low-Ca pyroxene (En 84-92 Wo 0-5 ), augite (En 71-56 Wo 20-31 ), graphite, diamond, Fe-metal, sulfides, chromite, and felsic glass. Pores are partly filled by secondary Fe-oxihydroxide and desert alteration products. Pores are surrounded by strongly reduced silicates. Clasts consist of fine-grained aggregates of polygonal olivine. These clasts have an approximately 250 lm wide reaction rim, in which olivine composition evolves progressively from the core composition (Fo 79-81 ) to the matrix composition ). Veins crossing the clasts comprise pyroxene, Fe-oxihydroxide, C-phases, and chromite. Clasts contain Ca-, Al-, and Cr-rich glass along olivine grain boundaries (<1 lm wide). We suggest that a significant portion of JaH 422, including olivine and all the pyroxenes, was molten as a result of an impact. In comparison with other impact-melted ureilites, JaH 422 shows the highest melt portion. Based on textural and compositional considerations, clasts and matrix probably originated from the same protolith, with the clasts representing relict olivine that survived, but was recrystallized in the impact melt. During the melt stage, the high availability of FeO and elevated temperatures controlled oxygen fugacity at values high enough to stabilize olivine with Fo 83-87 and chromite. Along pores, high Mg# compositions of silicates indicate that in a late stage or after melt crystallization FeO became less available and fO 2 conditions were controlled by C)CO + CO 2 .

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Petrogenesis of augite-bearing ureilites Hughes 009 and FRO 90054/93008 inferred from melt inclusions in olivine, augite and orthopyroxene

Cited by 21 publications

References 37 publications

K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

Stable isotopes and the noncarbonaceous derivation of ureilites, in common with nearly all differentiated planetary materials

Jiddat al Harasis 422: A ureilite with an extremely high degree of shock melting

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Petrogenesis of augite-bearing ureilites Hughes 009 and FRO 90054/93008 inferred from melt inclusions in olivine, augite and orthopyroxene

Cited by 21 publications

References 37 publications

K2O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

K2O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

Stable isotopes and the noncarbonaceous derivation of ureilites, in common with nearly all differentiated planetary materials

Jiddat al Harasis 422: A ureilite with an extremely high degree of shock melting

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Product

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K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle

K₂O‐rich trapped melt in olivine in the Nakhla meteorite: Implications for petrogenesis of nakhlites and evolution of the Martian mantle