Petrology and mineralogy of the angrite Northwest Africa 1670

Jambon, Albert; Boudouma, Omar; Fonteilles, Michel; Guillou, C. Le; Badia, D.; Barrat, Jean‐Alix

doi:10.1111/j.1945-5100.2008.tb00643.x

Cited by 24 publications

(49 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1991). Jambon et al. (2008) also note that the overgrowths on the large crystals appear undeformed so that NWA 1670 does not appear to be strongly shocked.…”

Section: Angrites and Their Propertiesmentioning

confidence: 90%

See 1 more Smart Citation

Impact histories of angrites, eucrites, and their parent bodies

Scott

Bottke

2011

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Abstract-Eucrites, which are probably from 4 Vesta, and angrites are the two largest groups of basaltic meteorites from the asteroid belt. The parent body of the angrites is not known but it may have been comparable in size to Vesta as it retained basalts and had a core dynamo. Both bodies were melted early by 26 Al and formed basalts a few Myr after they accreted. Despite these similarities, the impact histories of the angrites and eucrites are very different: angrites are very largely unshocked and none are breccias, whereas most eucrites are breccias and many are shocked. We attribute the lack of shocked and unbrecciated angrites to an impact, possibly at 4558 Myr ago-the radiometric age of the younger angrites-that extracted the angrites from their original parent body into smaller bodies. These bodies, which may have had a diameter of approximately 10 km, suffered much less impact damage than Vesta during the late heavy bombardment because small bodies retain shocked rocks less efficiently than large ones and because large bodies suffer near-catastrophic impacts that deposit vastly more impact energy per kg of target. Our proposed history for the angrites is comparable to that proposed by Bogard and Garrison (2003) for the unbrecciated eucrites with Ar-Ar ages of 4.48 Gyr and that for unbrecciated eucrites with anomalous oxygen isotopic compositions that did not come from Vesta. We infer that the original parent bodies of the angrites and the anomalous eucrites were lost from the belt when the giant planets migrated and the total mass of asteroids was severely depleted. Alternatively, their parent bodies may have formed in the terrestrial planet region and fragments of these bodies were scattered out to the primordial Main Belt as a consequence of terrestrial planet formation.

show abstract

“…1991). Jambon et al. (2008) also note that the overgrowths on the large crystals appear undeformed so that NWA 1670 does not appear to be strongly shocked.…”

Section: Angrites and Their Propertiesmentioning

confidence: 90%

“…However, Fig. 2b in Jambon et al. (2008) shows that the large olivines appear to have a recrystallized texture and are not mosaicized as in strongly shocked stage S4 rocks (Stöffler et al.…”

Section: Angrites and Their Propertiesmentioning

confidence: 95%

Impact histories of angrites, eucrites, and their parent bodies

Scott

Bottke

2011

Meteorit & Planetary Scien

View full text Add to dashboard Cite

show abstract

“…Only 19 angrites are recognized. Eight representative ones were analyzed here: D'Orbigny, NWA1296 and Sahara99555 consist of mainly Al-Ti-diopside-hedenbergite, Ca-rich olivine, anorthite and spinel olivine; they are also similar in bulk chemistry (Jambon et al, 2005); LEW86010 consists of $58 vol % Al-Ti-diopsidehedenbergite, 21 vol % plagioclase, 20 vol % olivine and minor amount of spinel, troilite, and Fe-Ni metal (Prinz et al, 1988); NWA1670 consists of large olivine xenocrysts, and fine-grained groundmass with pyroxene, anorthite and olivine (Jambon et al, 2008); NWA4801 is composed of Al-Ti-diopside-hedenbergite and pure anorthite (Irving and Kuehner, 2007); NWA2999 contains 64 vol % Ca-rich olivine, 23 vol % Al-Ti-diopside-hedenbergite, 4 vol % spinel, 1 vol % plagioclase and 8 vol % metal (Kuehner et al, Table 2 Comparison of the three iron purification chromatography protocols used in this study (see text for references). …”

Section: Sample Descriptionsmentioning

confidence: 99%

“…In addition, three modern island arc basalts (IABs) from New Britain (NMNH 116852-1, 116852-3 and 116852-11) were also analyzed here to test the accuracy of the measurements (see Dauphas et al (2009a) for a detailed discussion about IABs). (Jarosewich, 1990); NWA1950 (Gillet et al, 2005); Los Angeles (Warren et al, 2000); EETA79001, ALHA77005, Nakhla, ALH84001 (Lodders, 1998); Mil03346 (Day et al, 2006); GRO95555, MET00436, MET00424 ; NWA1461 (Warren et al, 2009);Shalka (McCarthy et al, 1972); ALHA77256 (Sack et al, 1991); NWA1240, NWA049 (Barrat et al, 2003); Cachari (Barrat et al, 2000); Agoult, Dag945 (Yamaguchi et al, 2009); Nuevo Laredo, NWA4523 (Barrat et al, 2007b); D'Orbigny, Sahara99555 (Mittlefehldt et al, 2002);LEW86010 (McKay et al, 1988); NWA1670 (Jambon et al, 2008); NWA1296 (Jambon et al, 2005); NWA2999 (Gellissen et al, 2007). i Weathering conditions are from MetBase (version 7.1).…”

Section: Sample Descriptionsmentioning

confidence: 99%

Iron isotope fractionation in planetary crusts

Wang

Moynier

Dauphas

et al. 2012

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

We present new high precision iron isotope data (d 56 Fe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite-eucrite-diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe compared to chondrites (by an average of +0.12& in d 56 Fe). While the reason for such fractionation is not completely understood, it might be related to isotopic fractionation by volatilization during accretion or more likely magmatic differentiation in the angrite parent-body. We also report precise data on martian and HED meteorites, yielding an average d 56 Fe of 0.00 ± 0.01&. Stannern-trend eucrites are isotopically heavier by +0.05& in d 56 Fe than other eucrites. We show that this difference can be ascribed to the enrichment of heavy iron isotopes in ilmenite during igneous differentiation. Preferential dissolution of isotopically heavy ilmenite during remelting of eucritic crust could have generated the heavy iron isotope composition of Stannern-trend eucrites. This supports the view that Stannern-trend eucrites are derived from main-group eucrite source magma by assimilation of previously formed asteroidal crust.These new results show that iron isotopes are not only fractionated in terrestrial and lunar basalts, but also in two other differentiated planetary crusts. We suggest that igneous processes might be responsible for the iron isotope variations documented in planetary crusts.

show abstract

“…) and it is possible, given the confirmed presence of carbonate inclusions in two other angrite samples (Jambon et al. , ), that the surface carbonate in D'Orbigny may have leached from inside the main sample. The presence of carbonate inclusions within pyroxene and unaltered pyrrhotite (Jambon et al.…”

Section: Discussionmentioning

confidence: 95%

Stable isotope analysis of carbon and nitrogen in angrites

Abernethy

Verchovsky

Starkey

et al. 2013

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Abstract-Angrites are a small group of ancient basaltic achondrites, notable for their unusual chemistry and extreme volatile depletion. No comprehensive study of indigenous light elements currently exists for the group. Measurement of the abundances and isotopic composition of carbon and nitrogen could provide information pertaining to the evolution of the angrite parent body. Bulk-sample stepped combustion analyses of five angrites and a glass separate from D'Orbigny were combined with earlier data and acid dissolution experiments of carbonates found in D'Orbigny to compile an inventory of indigenous carbon and nitrogen. Indigenous carbon combusted between 700°C and 1200°C, with abundances of 10-140 ppm and a mass-weighted d 13 C of À25 to À20& with the exception of D'Orbigny (d 13 C approximately À5&). Nitrogen was released at 850-1200 ºC, 1-20 ppm with a d 15 N À3& to +4&; again, D'Orbigny (d 15 N approximately +20 to +25&) was an exception. We interpret these components as largely indigenous and decoupled; the carbon in graphitic or amorphous form, while the nitrogen is present as a dissolved component in the silicates. No relationship with the textural sub-classification of angrites is apparent. We suggest that the angrite parent body contains a reservoir of reduced carbon and thus may have undergone a change in redox conditions, although the timing and mechanism for this remain unclear.

show abstract

Petrology and mineralogy of the angrite Northwest Africa 1670

Cited by 24 publications

References 21 publications

Impact histories of angrites, eucrites, and their parent bodies

Impact histories of angrites, eucrites, and their parent bodies

Iron isotope fractionation in planetary crusts

Stable isotope analysis of carbon and nitrogen in angrites

Contact Info

Product

Resources

About