Abstract
We report the oxygen-isotope compositions of relict and host olivine grains in six high-FeO porphyritic olivine chondrules in one of the most primitive carbonaceous chondrites, CO3.0 Yamato 81020. Because the relict grains predate the host phenocrysts, microscale in situ analyses of O-isotope compositions can help assess the degree of heterogeneity among chondrule precursors and constrain the nebular processes that caused these isotopic differences. In five of six chondrules studied, the Δ17O (=δ17O - 0.52 · δ18O) compositions of host phenocrysts are higher than those in low-FeO relict grains; the one exception is for a chondrule with a moderately high-FeO relict. Both the fayalite compositions as well as the O-isotope data support the view that the low-FeO relict grains formed in a previous generation of low-FeO porphyritic chondrules that were subsequently fragmented. It appears that most low-FeO porphyritic chondrules formed earlier than most high-FeO porphyritic chondrules, although there were probably some low-FeO chondrules that formed during the period when most high-FeO chondrules were forming.
| Original language | English |
|---|---|
| Pages (from-to) | 3599-3606 |
| Number of pages | 8 |
| Journal | Geochimica et Cosmochimica Acta |
| Volume | 68 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - Sep 1 2004 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Geochemistry and Petrology
Cite this
Oxygen-isotopic compositions of relict and host grains in chondrules in the Yamato 81020 CO3.0 chondrite. / Kunihiro, Takuya; Rubin, Alan E.; McKeegan, Kevin D.; Wasson, John T.
In: Geochimica et Cosmochimica Acta, Vol. 68, No. 17, 01.09.2004, p. 3599-3606.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Oxygen-isotopic compositions of relict and host grains in chondrules in the Yamato 81020 CO3.0 chondrite
AU - Kunihiro, Takuya
AU - Rubin, Alan E.
AU - McKeegan, Kevin D.
AU - Wasson, John T.
PY - 2004/9/1
Y1 - 2004/9/1
N2 - We report the oxygen-isotope compositions of relict and host olivine grains in six high-FeO porphyritic olivine chondrules in one of the most primitive carbonaceous chondrites, CO3.0 Yamato 81020. Because the relict grains predate the host phenocrysts, microscale in situ analyses of O-isotope compositions can help assess the degree of heterogeneity among chondrule precursors and constrain the nebular processes that caused these isotopic differences. In five of six chondrules studied, the Δ17O (=δ17O - 0.52 · δ18O) compositions of host phenocrysts are higher than those in low-FeO relict grains; the one exception is for a chondrule with a moderately high-FeO relict. Both the fayalite compositions as well as the O-isotope data support the view that the low-FeO relict grains formed in a previous generation of low-FeO porphyritic chondrules that were subsequently fragmented. It appears that most low-FeO porphyritic chondrules formed earlier than most high-FeO porphyritic chondrules, although there were probably some low-FeO chondrules that formed during the period when most high-FeO chondrules were forming.
AB - We report the oxygen-isotope compositions of relict and host olivine grains in six high-FeO porphyritic olivine chondrules in one of the most primitive carbonaceous chondrites, CO3.0 Yamato 81020. Because the relict grains predate the host phenocrysts, microscale in situ analyses of O-isotope compositions can help assess the degree of heterogeneity among chondrule precursors and constrain the nebular processes that caused these isotopic differences. In five of six chondrules studied, the Δ17O (=δ17O - 0.52 · δ18O) compositions of host phenocrysts are higher than those in low-FeO relict grains; the one exception is for a chondrule with a moderately high-FeO relict. Both the fayalite compositions as well as the O-isotope data support the view that the low-FeO relict grains formed in a previous generation of low-FeO porphyritic chondrules that were subsequently fragmented. It appears that most low-FeO porphyritic chondrules formed earlier than most high-FeO porphyritic chondrules, although there were probably some low-FeO chondrules that formed during the period when most high-FeO chondrules were forming.
UR - http://www.scopus.com/inward/record.url?scp=4844219801&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=4844219801&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2004.02.011
DO - 10.1016/j.gca.2004.02.011
M3 - Article
AN - SCOPUS:4844219801
VL - 68
SP - 3599
EP - 3606
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
IS - 17
ER -