CM and CO chondrites

A common parent body or asteroidal neighbors? Insights from chondrule silicates

Devin Schrader, Jemma Davidson

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

By investigating the petrology and chemical composition of type II (FeO-rich) chondrules in the Mighei-like carbonaceous (CM) chondrites we constrain their thermal histories and relationship to the Ornans-like carbonaceous (CO) chondrites. We identified FeO-rich relict grains in type II chondrules by their Fe/Mn ratios; their presence indicates chondrule recycling among type II chondrules. The majority of relict grains in type II chondrules are FeO-poor olivine grains. Consistent with previous studies, chemical similarities between CM and CO chondrite chondrules indicate that they had similar formation conditions and that their parent bodies probably formed in a common region within the protoplanetary disk. However, important differences such as mean chondrule size and the lower abundance of FeO-poor relicts in CM chondrite type II chondrules than in CO chondrites suggest CM and CO chondrules did not form together and they likely originate from distinct parent asteroids. Despite being aqueously altered, many CM chondrites contain pre-accretionary anhydrous minerals (i.e., olivine) that are among the least thermally metamorphosed materials in chondrites according to the Cr2O3 content of their ferroan olivine. The presence of these minimally altered pre-accretionary chondrule silicates suggests that samples to be returned from aqueously altered asteroids by the Hayabusa2 and OSIRIS-REx asteroid sample return missions, even highly hydrated, may contain silicates that can provide information about the pre-accretionary histories and conditions of asteroids Ryugu and Bennu, respectively.

Original languageEnglish (US)
Pages (from-to)157-171
Number of pages15
JournalGeochimica et Cosmochimica Acta
Volume214
DOIs
StatePublished - Oct 1 2017

Fingerprint

Silicates
Asteroids
chondrule
carbonaceous chondrite
parent body
silicate
asteroid
Petrology
chondrite
olivine
Minerals
Recycling
OSIRIS
Chemical analysis
history
petrology
recycling
chemical composition

Keywords

  • Accretion
  • Aqueous alteration
  • Chondrule
  • CM chondrite
  • Meteorite
  • Olivine
  • Relict
  • Thermal metamorphism

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

CM and CO chondrites : A common parent body or asteroidal neighbors? Insights from chondrule silicates. / Schrader, Devin; Davidson, Jemma.

In: Geochimica et Cosmochimica Acta, Vol. 214, 01.10.2017, p. 157-171.

Research output: Contribution to journalArticle

@article{a62674b83ef14df0a18a946251466f57,
title = "CM and CO chondrites: A common parent body or asteroidal neighbors? Insights from chondrule silicates",
abstract = "By investigating the petrology and chemical composition of type II (FeO-rich) chondrules in the Mighei-like carbonaceous (CM) chondrites we constrain their thermal histories and relationship to the Ornans-like carbonaceous (CO) chondrites. We identified FeO-rich relict grains in type II chondrules by their Fe/Mn ratios; their presence indicates chondrule recycling among type II chondrules. The majority of relict grains in type II chondrules are FeO-poor olivine grains. Consistent with previous studies, chemical similarities between CM and CO chondrite chondrules indicate that they had similar formation conditions and that their parent bodies probably formed in a common region within the protoplanetary disk. However, important differences such as mean chondrule size and the lower abundance of FeO-poor relicts in CM chondrite type II chondrules than in CO chondrites suggest CM and CO chondrules did not form together and they likely originate from distinct parent asteroids. Despite being aqueously altered, many CM chondrites contain pre-accretionary anhydrous minerals (i.e., olivine) that are among the least thermally metamorphosed materials in chondrites according to the Cr2O3 content of their ferroan olivine. The presence of these minimally altered pre-accretionary chondrule silicates suggests that samples to be returned from aqueously altered asteroids by the Hayabusa2 and OSIRIS-REx asteroid sample return missions, even highly hydrated, may contain silicates that can provide information about the pre-accretionary histories and conditions of asteroids Ryugu and Bennu, respectively.",
keywords = "Accretion, Aqueous alteration, Chondrule, CM chondrite, Meteorite, Olivine, Relict, Thermal metamorphism",
author = "Devin Schrader and Jemma Davidson",
year = "2017",
month = "10",
day = "1",
doi = "10.1016/j.gca.2017.07.031",
language = "English (US)",
volume = "214",
pages = "157--171",
journal = "Geochmica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - CM and CO chondrites

T2 - A common parent body or asteroidal neighbors? Insights from chondrule silicates

AU - Schrader, Devin

AU - Davidson, Jemma

PY - 2017/10/1

Y1 - 2017/10/1

N2 - By investigating the petrology and chemical composition of type II (FeO-rich) chondrules in the Mighei-like carbonaceous (CM) chondrites we constrain their thermal histories and relationship to the Ornans-like carbonaceous (CO) chondrites. We identified FeO-rich relict grains in type II chondrules by their Fe/Mn ratios; their presence indicates chondrule recycling among type II chondrules. The majority of relict grains in type II chondrules are FeO-poor olivine grains. Consistent with previous studies, chemical similarities between CM and CO chondrite chondrules indicate that they had similar formation conditions and that their parent bodies probably formed in a common region within the protoplanetary disk. However, important differences such as mean chondrule size and the lower abundance of FeO-poor relicts in CM chondrite type II chondrules than in CO chondrites suggest CM and CO chondrules did not form together and they likely originate from distinct parent asteroids. Despite being aqueously altered, many CM chondrites contain pre-accretionary anhydrous minerals (i.e., olivine) that are among the least thermally metamorphosed materials in chondrites according to the Cr2O3 content of their ferroan olivine. The presence of these minimally altered pre-accretionary chondrule silicates suggests that samples to be returned from aqueously altered asteroids by the Hayabusa2 and OSIRIS-REx asteroid sample return missions, even highly hydrated, may contain silicates that can provide information about the pre-accretionary histories and conditions of asteroids Ryugu and Bennu, respectively.

AB - By investigating the petrology and chemical composition of type II (FeO-rich) chondrules in the Mighei-like carbonaceous (CM) chondrites we constrain their thermal histories and relationship to the Ornans-like carbonaceous (CO) chondrites. We identified FeO-rich relict grains in type II chondrules by their Fe/Mn ratios; their presence indicates chondrule recycling among type II chondrules. The majority of relict grains in type II chondrules are FeO-poor olivine grains. Consistent with previous studies, chemical similarities between CM and CO chondrite chondrules indicate that they had similar formation conditions and that their parent bodies probably formed in a common region within the protoplanetary disk. However, important differences such as mean chondrule size and the lower abundance of FeO-poor relicts in CM chondrite type II chondrules than in CO chondrites suggest CM and CO chondrules did not form together and they likely originate from distinct parent asteroids. Despite being aqueously altered, many CM chondrites contain pre-accretionary anhydrous minerals (i.e., olivine) that are among the least thermally metamorphosed materials in chondrites according to the Cr2O3 content of their ferroan olivine. The presence of these minimally altered pre-accretionary chondrule silicates suggests that samples to be returned from aqueously altered asteroids by the Hayabusa2 and OSIRIS-REx asteroid sample return missions, even highly hydrated, may contain silicates that can provide information about the pre-accretionary histories and conditions of asteroids Ryugu and Bennu, respectively.

KW - Accretion

KW - Aqueous alteration

KW - Chondrule

KW - CM chondrite

KW - Meteorite

KW - Olivine

KW - Relict

KW - Thermal metamorphism

UR - http://www.scopus.com/inward/record.url?scp=85027869602&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85027869602&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2017.07.031

DO - 10.1016/j.gca.2017.07.031

M3 - Article

VL - 214

SP - 157

EP - 171

JO - Geochmica et Cosmochimica Acta

JF - Geochmica et Cosmochimica Acta

SN - 0016-7037

ER -