The Milton pallasite and South Byron Trio irons: Evidence for oxidation and core crystallization

McCoy, Timothy J.; Corrigan, C. M.; Nagashima, K.; Reynolds, V. S.; Ash, R. D.; McDonough, William F.; Yang, Jijin; Goldstein, Joseph I.; Hilton, Connor D.

doi:10.1016/j.gca.2019.06.005

Cited by 31 publications

(25 citation statements)

References 27 publications

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“…; McCoy et al. ) plot in a similar area close to the fragment, which suggests a similar formation region. However, the meteorite Deep Springs is exceptionally free of nonmetallic inclusions (Axon and Smith ) and it is not possible to create a closer relationship between Deep Springs and the fragment.…”

Section: Discussionmentioning

confidence: 78%

“…3, the fragment plots in the field of CB chondrites. Two iron meteorites, Tucson and Deep Springs (Clayton and Mayeda 1996), and olivines from the pallasite Milton (Jones et al 2003;McCoy et al 2019) plot in a similar area close to the fragment, which suggests a similar formation region. However, the meteorite Deep Springs is exceptionally free of nonmetallic inclusions (Axon and Smith 1972) and it is not possible to create a closer relationship between Deep Springs and the fragment.…”

Section: Discussionmentioning

confidence: 95%

“…Literature data: Deep Springs and Tucson (Clayton and Mayeda ), Milton olivines (McCoy et al. ), CM chondrites (Clayton and Mayeda ), CV chondrites (Clayton and Mayeda ; Greenwood et al. ), CB chondrites (Krot et al.…”

Section: Resultsmentioning

confidence: 99%

“…; McCoy et al. ). The Milton olivine(Fa 17.2 ) is also Fe‐rich compared to most of the main‐group pallasites.…”

Section: Discussionmentioning

confidence: 97%

“…McCoy et al. () concluded that the Milton pallasite originates from a differentiated parent body with a small core and a large Fe‐rich mantle. This Fe‐rich mantle was stripped of the parent body caused by impacts.…”

Section: Discussionmentioning

confidence: 99%

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Accretion of differentiated achondritic and aqueously altered chondritic materials in the early solar system—Significance of an igneous fragment in the CM chondrite NWA 12651

Ebert

Patzek

Lentfort

et al. 2019

Meteorit & Planetary Scien

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One approach to decipher the dynamics of material transport and planetary accretion in the early solar system is to investigate xenolithic fragments in meteorites. In this work, we examined an igneous fragment from the NWA 12651 meteorite—the first igneous fragment found in any CM chondrite—by analyzing its mineralogy, rare earth elements (REEs), and O‐isotopes. The study shows that the exsolution lamellae of the igneous fragment consist of Fe‐rich and Ca‐rich pyroxene. Thus, the fragment was part of a progressive crystallization in a closed system, such as in a depleted magma reservoir or mantle. In this environment, the pyroxene co‐crystallized with plagioclase, resulting in a negative Eu anomaly and enrichment of the heavy REEs compared to the light REEs. The O‐isotopes of the fragment are more 16O‐enriched than the mafic minerals in the matrix or in other bulk CM chondrites; therefore, the fragment was formed in a different region than the NWA 12651 parent body. The iron meteorites Tucson and Deep Springs, the pallasite Milton, and the CB chondrites have similar O‐isotopes as the igneous fragment. However, no direct connection can be drawn and it is questionable if the fragment shares a same parent body with one of these meteorites. The close formation region to the CB chondrites may suggest a formation of the fragment in the carbonaceous chondrite region. Thus, a wide transport through the nebula of the early solar system may not have been necessary to move the fragment to the CM chondrite formation region.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

“…; McCoy et al. ). The Milton olivine(Fa 17.2 ) is also Fe‐rich compared to most of the main‐group pallasites.…”

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Accretion of differentiated achondritic and aqueously altered chondritic materials in the early solar system—Significance of an igneous fragment in the CM chondrite NWA 12651

Ebert

Patzek

Lentfort

et al. 2019

Meteorit & Planetary Scien

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Deciphering Redox State for a Metal-Rich World

et al. 2022

Self Cite

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The Psyche mission’s Oxidation-Reduction Working Group is focused on understanding, determining, and applying the redox state of (16) Psyche to understand the origin of a metal-rich world. The oxidation-reduction state of an asteroid, along with its temperature, parent body size, and composition, is a key parameter in determining the history of an asteroid. Determining the redox state from spacecraft data is most easily done by examining potential metal-oxide buffer pairs. The occurrence of Ni, Fe, C, Cr, P and Si, in that order, in the metal or sulfide phase of an asteroidal body indicates increasingly reduced conditions. Key observations by the Imager and Gamma-Ray and Neutron Spectrometer (GRNS) of Psyche can bracket the redox state using metal-oxide buffers. The presence of Fe,Ni metal can be confirmed by the ratios of Fe/O or Fe/Si and the concentration of Ni variability in metal across the asteroid can be determined by GRNS. The FeO concentration of silicates is complementary to the Ni concentration of metal and can be constrained using filters on the Imager. The presence of FeO in silicates from ground-based observations is one of the few measurements we already have of redox state, although available data permit a wide range of silicate compositions and mineralogies. The presence of C, P or Si concentrated in the metallic, Fe-rich portion of the asteroid, as measured by GRNS, or Ca-sulfide, determined by imaging, would indicate increasingly reducing conditions. Linkage to known types of meteorites, whether metal-rich chondrites, stony-irons or irons, expands the mineralogical, chemical and isotopic data not available from remote observations alone. Redox also controls both silicate and metal mineralogy, influencing differentiation, solidification, and subsolidus cooling, including the relative abundance of sulfur in the core and possible magnetic signatures. The redox state of Psyche, if a fully-differentiated metallic core, might constrain the location and timing of both the formation of Psyche and any oxidation it might have experienced.

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Nickel-rich, volatile depleted iron meteorites: Relationships and formation processes

Corrigan¹,

Nagashima

Hilton

et al. 2022

Geochimica et Cosmochimica Acta

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The Milton pallasite and South Byron Trio irons: Evidence for oxidation and core crystallization

Cited by 31 publications

References 27 publications

Accretion of differentiated achondritic and aqueously altered chondritic materials in the early solar system—Significance of an igneous fragment in the CM chondrite NWA 12651

Accretion of differentiated achondritic and aqueously altered chondritic materials in the early solar system—Significance of an igneous fragment in the CM chondrite NWA 12651

Deciphering Redox State for a Metal-Rich World

Nickel-rich, volatile depleted iron meteorites: Relationships and formation processes

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