Origin of ureilites inferred from a SIMS oxygen isotopic and trace element study of clasts in the Dar al Gani 319 polymict ureilite

Kita, N. T.; Ikeda, Yukio; Togashi, S.; Liu, Yongzhong; Morishita, Y.; Weisberg, M. K.

doi:10.1016/j.gca.2004.03.020

Cited by 96 publications

(153 citation statements)

References 31 publications

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“…2). The polymict ureilite DaG 319, which contains feldspathic lithologies that may be derived from the missing silicate melts from the ureilite parent body (Cohen et al, 2004;Downes and Mittlefehldt, 2006;Goodrich et al, 2004;Ikeda and Prinz, 2001;Kita et al, 2004), has 187 Os/ 188 Os of 0.1262 ± 0.0004 (2σ) indistinguishable from the monomict ureilite average [0.1257 ± 0.0024 (1σ)]. Inverse Os concentrations and Os isotopic compositions of the ureilites are (r 2 =0.66) correlated (Fig.…”

Section: Resultsmentioning

confidence: 99%

Osmium isotope systematics of ureilites

Rankenburg

Brandon

Humayun

2007

Geochimica et Cosmochimica Acta

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The 187 Os/ 188 Os for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite 187 Os/ 188 Os ratios span a range from 0.11739 to 0.13018, with an average of 0.1258 ± 0.0023 (1σ), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of 187 Os/ 188 Os measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187 Os/ 188 Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body.3

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Section: Resultsmentioning

confidence: 99%

Osmium isotope systematics of ureilites

Rankenburg

Brandon

Humayun

2007

Geochimica et Cosmochimica Acta

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“…2) falls in the field of the ureilites and feldspathic clasts from polymict ureilites (3,20,21); (ii) the feldspar mineralogy is very similar to the rare feldspathic clasts found in some polymict ureilites, which are considered as remnants of UPB melts (5); and (iii) it is most likely part of asteroid 2008 TC 3 , which was shown to be a fragment of an asteroid dominated by ureilitic lithologies (10,11).…”

Section: Discussionmentioning

confidence: 99%

Trachyandesitic volcanism in the early Solar System

Bischoff¹,

Horstmann²,

Barrat

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

102

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Volcanism is a substantial process during crustal growth on planetary bodies and well documented to have occurred in the early Solar System from the recognition of numerous basaltic meteorites. Considering the ureilite parent body (UPB), the compositions of magmas that formed a potential UPB crust and were complementary to the ultramafic ureilite mantle rocks are poorly constrained. Among the Almahata Sitta meteorites, a unique trachyandesite lava (with an oxygen isotope composition identical to that of common ureilites) documents the presence of volatile-and SiO 2 -rich magmas on the UPB. The magma was extracted at low degrees of disequilibrium partial melting of the UPB mantle. This trachyandesite extends the range of known ancient volcanic, crust-forming rocks and documents that volcanic rocks, similar in composition to trachyandesites on Earth, also formed on small planetary bodies ∼4.56 billion years ago. It also extends the volcanic activity on the UPB by ∼1 million years (Ma) and thus constrains the time of disruption of the body to later than 6.5 Ma after the formation of Ca-Al-rich inclusions.A large number of planetary embryos, tens to hundreds of kilometers in size, accreted within the early Solar System. In some of these embryos, internal heating triggered melting and differentiation, giving rise to a varied suite of lithologies as documented by the achondritic meteorites. Planetary crustal growth occurs via both volcanic eruptions and plutonic intrusions. Constraining these processes and the diversity of crustal materials that formed the outermost solid shell of planetary bodies is crucial for understanding Solar System planetary processes and evolution.Ureilites are among the most common achondrites and represent remnants of the mantle from a planetary body from which magmas have been extensively extracted (1−4). Several details of ureilite petrogenesis (e.g., the mode of melt extraction) remain controversial (e.g., refs. 1 and 2) because crustal rocks from the ureilite parent body (UPB) have not yet been discovered. Although tiny remnants of feldspathic and felsic melts from ureilitic breccias have been interpreted as UPB basalts or products of partial melting of plagioclase-bearing cumulates (e.g., refs. 5 and 6), it is generally assumed that the complementary melts were lost to space during explosive eruptions (e.g., refs. 7-9).A unique opportunity to gain new insights into ureilite petrogenesis was provided by the polymict asteroid 2008 TC 3 that impacted our planet October 7, 2008, in the Nubian Desert, Sudan, containing various ureilitic and ureilite-related fragments (10, 11). Among its remnant fragments collected in the strewn field, collectively named the "Almahata Sitta" meteorites, the sample ALM-A (Almahata Sitta trachyandesitic meteorite) was recovered (12). ALM-A weights 24.2 g and is covered with a greenish and shiny fusion crust (Fig. 1).The ALM-A sample described here is the only SiO 2 -rich, rapidly cooled volcanic rock among the meteorites in our collections. This rock is textura...

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“…16) and thus does not lead to ureilite-like olivine-pigeonite residues; superchondritic Ca/Al ratios are required. Although this conclusion has been challenged (Kita et al 2004), our recent re-evaluation has shown it to be robust. We assume the total iron content of the bulk UPB to have been similar to that of the most Fe-rich CV chondrites, or mg = ∼62 if all Fe is in the form of FeO (labelled mg 65 in Fig.…”

Section: Structure Of the Ureilite Parent Bodymentioning

confidence: 98%

Northwest Africa 1500: Plagioclase-bearing monomict ureilite or ungrouped achondrite?

Goodrich

Wlotzka

Ross

et al. 2006

Meteoritics &Amp; Planetary Science

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Abstract-Northwest Africa (NWA) 1500 is an ultramafic meteorite dominated by coarse (∼100-500 μm) olivine (95-96%), augite (2-3%), and chromite (0.6-1.6%) in an equilibrated texture. Plagioclase (0.7-1.8%) occurs as poikilitic grains (up to ∼3 mm) in vein-like areas that have concentrations of augite and minor orthopyroxene. Other phases are Cl-apatite, metal, sulfide, and graphite. Olivine ranges from Fo 65-73, with a strong peak at Fo 68-69. Most grains are reversezoned, and also have ∼10-30 μm reduction rims. In terms of its dominant mineralogy and texture, NWA 1500 resembles the majority of monomict ureilites. However, it is more ferroan than known ureilites (Fo ≥75) and other mineral compositional parameters are out of the ureilite range as well. Furthermore, neither apatite nor plagioclase have ever been observed, and chromite is rare in monomict ureilites. Nevertheless, this meteorite may be petrologically related to the rare augite-bearing ureilites and represent a previously unsampled part of the ureilite parent body (UPB). The Mn/Mg ratio of its olivine and textural features of its pyroxenes are consistent with this interpretation. However, its petrogenesis differs from that of known augitebearing ureilites in that: 1) it formed under more oxidized conditions; 2) plagioclase appeared before orthopyroxene in its crystallization sequence; and 3) it equilibrated to significantly lower temperatures (800-1000 °C, from two-pyroxene and olivine-chromite thermometry). Formation under more oxidized conditions and the appearance of plagioclase before orthopyroxene could be explained if it formed at a greater depth on the UPB than previously sampled. However, its significantly different thermal history (compared to ureilites) may more plausibly be explained if it formed on a different parent body. This conclusion is consistent with its oxygen isotopic composition, which suggests that it is an ungrouped achondrite. Nevertheless, the parent body of NWA 1500 may have been compositionally and petrologically similar to the UPB, and may have had a similar differentiation history.

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Origin of ureilites inferred from a SIMS oxygen isotopic and trace element study of clasts in the Dar al Gani 319 polymict ureilite

Cited by 96 publications

References 31 publications

Osmium isotope systematics of ureilites

Osmium isotope systematics of ureilites

Trachyandesitic volcanism in the early Solar System

Northwest Africa 1500: Plagioclase-bearing monomict ureilite or ungrouped achondrite?

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