Origin of metallic Fe-Ni in Renazzo and related chondrites

Lee, Min Sung; Rubin, Alan E.; Wasson, J. T.

doi:10.1016/0016-7037(92)90206-x

Cited by 65 publications

(45 citation statements)

References 25 publications

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“…Its organic inventory and maturity parameters are not consistent with high levels of thermal processing as proposed by Lee et al (1992). Its MNR suggests that its alteration may have been mild enough to inhibit full isomerism of α-species.…”

Section: Discussionmentioning

confidence: 92%

“…They contain a mineral matrix indicative of low temperature aqueous processing, abundant free metal which may have a presolar source (Bischoff et al 1993a) and anomalous nitrogen isotopic compositions representative of an interstellar contribution (Alexander et al 1998;Kolodny et al 1980;Kung and Clayton 1978). There may also be evidence of mild thermal (anhydrous) alteration (Lee et al 1992) and shock (Cain et al 1986;Kallemeyn and Wasson 1982). The CR chondrites contain evidence of varying extents of aqueous alteration, indicated by differences in the degree of alteration of chondrule mesostasis; from replacement by phyllosilicates in Renazzo and Al Rais to unaltered glassy mesostasis in other CRs (Brearley 2004).…”

Section: Introductionmentioning

confidence: 99%

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Molecular and isotopic indicators of alteration in CR chondrites

Pearson

Sephton

Gilmour

2006

Meteoritics &Amp; Planetary Science

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Molecular and isotopic indicators of alteration in CR chondritesRenazzo, Al Rais, and Y-790112 release qualitatively similar pyrolysis products, although there are some variations. Al Rais' macromolecular structure contains substantially higher relative abundances of alkylated and oxidized species and relatively lighter δ 15 N, suggesting that it has endured more extensive aqueous processing than the other CR chondrites. Renazzo appears relatively unprocessed, with a low degree of alkylation, a lack of detectable nitrogen-bearing components, and low methylnaphthalene ratio. EET 87770's low abundance of alkylated species suggests its macromolecular structure may be relatively condensed, with condensation potentially assisted by a period of mild thermal alteration.

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Molecular and isotopic indicators of alteration in CR chondrites

Pearson

Sephton

Gilmour

2006

Meteoritics &Amp; Planetary Science

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“…The FeNi metal in the AOAs could be a product of such a reduction reaction, removing a constraint on P tot . Lee et al (1992) found that some metal in the Renazzo CR chondrite is zoned with Ni and Co decreasing and Fe increasing at the edges of the grains. They interpreted the low Ni and Co to be the result of dilution by Fe, produced by FeO reduction during metamorphism on the CR parent body.…”

Section: Formation Of Mn-rich Forsteritementioning

confidence: 99%

Petrology and origin of amoeboid olivine aggregates in CR chondrites

Weisberg

Connolly

Ebel

2004

Meteorit & Planetary Scien

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Abstract-Amoeboid olivine aggregates (AOAs) are irregularly shaped, fine-grained aggregates of olivine and Ca, Al-rich minerals and are important primitive components of CR chondrites. The AOAs in CR chondrites contain FeNi metal, and some AOAs contain Mn-rich forsterite with up to 0.7 MnO and Mn:Fe ratios greater than one. Additionally, AOAs in the CR chondrites do not contain secondary phases (nepheline and fayalitic olivine) that are found in AOAs in some CV chondrites. The AOAs in CR chondrites record a complex petrogenetic history that included nebular gas-solid condensation, reaction of minerals with the nebular gas, small degrees of melting, and sintering of the assemblage. A condensation origin for the Mn-rich forsterite is proposed. The Mn-rich forsterite found in IDPs, unequilibrated ordinary chondrite matrix, and AOAs in CR chondrites may have had a similar origin.A type A calcium, aluminum-rich inclusion (CAI) with an AOA attached to its Wark-Lovering rim is also described. This discovery reveals a temporal relationship between AOAs and type A inclusions. Additionally, a thin layer of forsterite is present as part of the Wark-Lovering rim, revealing the crystallization of olivine at the end stages of Wark-Lovering rim formation. The Ca, Alrich nodules in the AOAs may be petrogenetically related to the Ca, Al-rich minerals in WarkLovering rims on type A CAIs. AOAs are chondrite components that condensed during the final stage of Wark-Lovering rim formation but, in general, were temporally, spatially, or kinetically isolated from reacting with the nebula vapor during condensation of the lower temperature minerals that were commonly present as chondrule precursors.

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“…The CR (Renazzo-type) chondrites are primitive meteorites that although hydrously altered did not suffer significant thermal metamorphism, so the properties of their chondrules are important records of chondrule formation (Mason and Wiik 1962, Wood 1962, 1963Lee et al 1992;Weisberg et al 1992Weisberg et al , 1993Weisberg et al , 1995Krot et al 2002;DeGregorio et al 2008). Renazzo is one of only two CR chondrite falls.…”

Section: Introductionmentioning

confidence: 99%

“…Wood and McSween (1977, p. 368) concluded: "the concentric arrangement of metal in these objects suggests that they grew, with successive layers being added by accretion or condensation." Alternatively, additional Fe was incorporated into the metal on the chondrule rims due to FeO reduction from adjoining silicates (Lee et al 1992). Connolly et al (2001) analyzed PGE distributions in CR chondrite metal and argued that some rim metal grains, rich in refractory siderophiles, are original to primary formation of the chondrules.…”

Section: Introductionmentioning

confidence: 99%

Shape, metal abundance, chemistry, and origin of chondrules in the Renazzo (CR) chondrite

Ebel

Weisberg

Hertz

et al. 2008

Meteorit & Planetary Scien

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Abstract-We used synchrotron X-ray microtomography to image in 3-dimensions (3D) eight whole chondrules in a ~1 cm 3 piece of the Renazzo (CR) chondrite at ~17 µm per volume element (voxel) edge. We report the first volumetric (3D) measurement of metal/silicate ratios in chondrules and quantify indices of chondrule sphericity. Volumetric metal abundances in whole chondrules range from 1 to 37 volume % in 8 measured chondrules and by inspection in tomography data. We show that metal abundances and metal grain locations in individual chondrules cannot be reliably obtained from single random 2D sections. Samples were physically cut to intersect representative chondrules multiple times and to verify 3D data. Detailed 2D chemical analysis combined with 3D data yield highly variable whole-chondrule Mg/Si ratios with a supra-chondritic mean value, yet the chemically diverse, independently formed chondrules are mutually complementary in preserving chondritic (solar) Fe/Si ratios in the aggregate CR chondrite. These results are consistent with localized chondrule formation and rapid accretion resulting in chondrule + matrix aggregates (meteorite parent bodies) that preserve the bulk chondritic composition of source regions.

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Origin of metallic Fe-Ni in Renazzo and related chondrites

Cited by 65 publications

References 25 publications

Molecular and isotopic indicators of alteration in CR chondrites

Molecular and isotopic indicators of alteration in CR chondrites

Petrology and origin of amoeboid olivine aggregates in CR chondrites

Shape, metal abundance, chemistry, and origin of chondrules in the Renazzo (CR) chondrite

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