Composition and classification of clasts in the St. Mesmin LL chondrite breccia

Chou, Chen‐Lin; Sears, D. W. G.; Wasson, J. T.

doi:10.1016/0012-821x(81)90052-2

Cited by 9 publications

(5 citation statements)

References 24 publications

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“…Indeed, a similar inclusion of H‐type chondrite was found in the St. Mesmin LL6 chondrite (Chou et al. ). Furthermore, a centimeter‐scale L‐type clast has been described on the LL chondrite NWA 5764 (Gattacceca et al.…”

Section: Discussionsupporting

confidence: 63%

Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)

Bezaeva

Badyukov

Назаров

et al. 2014

Meteorit & Planetary Scien

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Abstract-Here we characterize the magnetic properties of the Chelyabinsk chondrite (LL5, S4, W0) and constrain the composition, concentration, grain size distribution, and mineral fabric of the meteorite's magnetic mineral assemblage. Data were collected from 10 to 1073 K and include measurements of low-field magnetic susceptibility (v 0 ), the anisotropy of v 0 , hysteresis loops, first-order reversal curves, M€ ossbauer spectroscopy, and X-ray microtomography. The REM and REM 0 paleointensity protocols suggest that the only magnetizations recorded by the chondrite are components of the Earth's magnetic field acquired during entry into our planet's atmosphere. The Chelyabinsk chondrite consists of light and dark lithologies. Fragments of the light lithology show logv 0 = 4.57 AE 0.09 (s.d.) (n = 135), while the dark lithology shows 4.65 AE 0.09 (n = 39) (where v 0 is in 10 À9 m 3 kg À1 ). Thus, Chelyabinsk is three times more magnetic than the average LL5 fall, but is similar to a subgroup of metal-rich LL5 chondrites (Paragould, Aldsworth, Bawku, Richmond) and L/LL5 chondrites (Glanerbrug, Knyahinya). The meteorite's roomtemperature magnetization is dominated by multidomain FeNi alloys taenite and kamacite (no tetrataenite is present). However, below approximately 75 K remanence is dominated by chromite. The metal contents of the light and dark lithologies are 3.7 and 4.1 wt%, respectively, and are based on values of saturation magnetization.

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Section: Discussionsupporting

confidence: 63%

Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)

Bezaeva

Badyukov

Назаров

et al. 2014

Meteorit & Planetary Scien

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“…Xenolithic clasts, such as the one reported here, have been reported by Dodd and Jarosewich (1976), Chou et al (1981), Casanova et al (1987), Hutchison et al (1988), Sack et al (1994), and Sokol et al (2007). Of these, the clasts found in St. Mesmin (Dodd and Jarosewich 1976) and those found in Cabezo de Mayo (L-LL6) and Sevilla (LL4), first reported in abstract form by Casanova et al (1987), seem to bear the closest resemblance to the Peace River clast under consideration here.…”

Section: Insights From Similar Clasts In Other Meteoritessupporting

confidence: 63%

“…Host and clast compositions for the Cabezo de Mayo (CdM) L6 chondrite (Clayton et al 1991) are shown for comparison. The clast 368d3 described by Dodd and Jarosewich (1976) and Chou et al (1981) in the St. Mesmin unequilibrated chondrite breccia shows similar mineralogical and chemical properties to the Peace River clast and has a similar textural relationship to its host. However, the St. Mesmin clast contains olivine phenocrysts in a matrix of microcrystalline pyroxene and glass with minor chromite, troilite, and metal (Dodd and Jarosewich 1976).…”

Section: Insights From Similar Clasts In Other Meteoritesmentioning

confidence: 86%

An igneous-textured clast in the Peace River meteorite: insights into accretion and metamorphism of asteroids in the early solar system

et al. 2013

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The mineralogy, petrology, and geochemistry of an igneous-textured clast in the Peace River L6 chondrite meteorite was examined to determine the roles of nebular processes, accretion, and parent-body metamorphism in its origin. The centimetre-scale clast is grey and fine grained and is in sharp contact with the host chondrite. Two sub-millimetre veins cut across both the clast and host, indicating that the clast formed prior to the impact (shock) event(s) that produced the numerous veins present in the Peace River meteorite. The clast and host are indistinguishable in terms of mineral compositions. In contrast, there are differences in modal mineralogy, texture, as well as trace element and oxygen isotope composition between the clast and host. These differences strongly suggest that the clast was formed by impact melting of LL-group chondritic material involving loss of Fe-FeS and phosphate components, followed by relatively rapid cooling and incorporation into the Peace River host meteorite. Subsequent metamorphism on the Peace River parent body caused recrystallization of the clast and homogenization of mineral compositions and thermally labile element abundances between the clast and host. Shock metamorphism, including formation of shock melt veins, occurred post-metamorphism, during fragmentation of the L chondrite parent body. The results suggest that the formation of the Peace River parent asteroid included the incorporation of material from other asteroids and that the pre-metamorphic protolith was a breccia. Accordingly, we propose that the Peace River meteorite be reclassified as a polymict breccia.Résumé : La minéralogie, la pétrologie et la géochimie d'un claste à texture ignée dans la météorite chondrite Peace River L6 ont été étudiées afin de déterminer les rôles des processus nébulaires, d'accrétion et de métamorphisme quant à l'origine de l'amas parent. Le claste d'échelle centimétrique est gris et à grain fin; il est de plus en contact net avec la chondrite hôte. Deux veines de taille inférieure à un millimètre recoupent le claste et la roche hôte, indiquant que le claste s'est formé avant le(s) événement(s) d'impact qui a(ont) produit les nombreuses veines présentes dans la météorite Peace River. Le clase et son hôte ont exactement les mêmes compositions minérales. Par contre, il existe des différences dans la minéralogie modale, la texture, les éléments traces et la composition des isotopes d'oxygène entre le claste et la roche hôte. Ces différences suggèrent fortement que le claste ait été formé par la fusion sous impact du matériel chondritique du groupe LL, impliquant la perte des composantes Fe-FeS et phosphatiques, la fusion a été suivie d'un refroidissement relativement rapide et de l'incorporation dans la météorite hôte Peace River. Un métamorphisme subséquent sur l'amas parent Peace River a causé la recristallisation du claste et l'homogénéisation des compositions minérales et des abondances des éléments labiles thermiques entre le claste et la roche hôte. Un métamorphisme de choc, incl...

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“…In the St. Mesmin LL chondrite regolith breccia, a heavily shocked H4 clast, with an original minimum size of 4 × 2 × 2 cm, was first mentioned by Pellas (), and studied by Dodd () and Chou et al. (). This clast has a K‐Ar age 1.36 ± 0.05 Ga, much younger than the mean age of 4.40 ± 0.26 Ga for other clasts in this meteorite (Schultz and Signer ).…”

Section: Breccia Formation and Significancementioning

confidence: 99%

“…The H xenolith was interpreted as part of the projectile that ejected the St. Mesmin meteoroid from its parent body (Chou et al. ). Glanerbrug LL chondrite contains L clasts whose size and modal abundances are not constrained in the abstracts in which it was described (Welten et al.…”

Section: Breccia Formation and Significancementioning

confidence: 99%

Young asteroid mixing revealed in ordinary chondrites: The case of NWA 5764, a polymict LL breccia with L clasts

Gattacceca

Krzesińska

Marrocchi

et al. 2017

Meteorit & Planetary Scien

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Polymict chondritic breccias-rocks composed of fragments originating from different chondritic parent bodies-are of particular interest because they give insights into the mixing of asteroids in the main asteroid belt (occurrence, encounter velocity, transfer time). We describe Northwest Africa (NWA) 5764, a brecciated LL6 chondrite that contains a >16 cm 3 L4 clast. The L clast was incorporated in the breccia through a nondestructive, low-velocity impact. Identical cosmic-ray exposure ages of the L clast and the LL host (36.6 AE 5.8 Myr), suggest a short transfer time of the L meteoroid to the LL parent body of 0.1 AE 8.1 Myr, if that meteoroid was no larger than a few meters. NWA 5764 (together with St. Mesmin, Dimmitt, and Glanerbrug) shows that effective mixing is possible between ordinary chondrite parent bodies. In NWA 5764 this mixing occurred after the peak of thermal metamorphism on the LL parent body, i.e., at least several tens of Myr after the formation of the solar system. The U,Th-He ages of the L clast and LL host, identical at about 2.9 Ga, might date the final assembly of the breccia, indicating relatively young mixing in the main asteroid belt as previously evidenced in St. Mesmin.

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Composition and classification of clasts in the St. Mesmin LL chondrite breccia

Cited by 9 publications

References 24 publications

Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)

Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)

An igneous-textured clast in the Peace River meteorite: insights into accretion and metamorphism of asteroids in the early solar system

Young asteroid mixing revealed in ordinary chondrites: The case of NWA 5764, a polymict LL breccia with L clasts

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