TY - JOUR
T1 - A reclassification of Northwest Africa 2900 from CV3 to CK3 chondrite
AU - Torrano, Zachary A.
AU - Davidson, Jemma
AU - Wadhwa, Meenakshi
N1 - Funding Information:
We thank Axel Wittmann and Ken Domanik for their assistance with the electron microprobes at Arizona State University and the University of Arizona, respectively. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI‐ECCS‐1542160. This manuscript was improved by helpful reviews from Alan Rubin, Tasha Dunn, and Marina Ivanova, and the editorial expertise of AE Cyrena Goodrich. This work was supported by NASA grants NNX15AH41G to M. W. and NNH19ZDA005K to Z. T. and M. W.
Funding Information:
We thank Axel Wittmann and Ken Domanik for their assistance with the electron microprobes at Arizona State University and the University of Arizona, respectively. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160. This manuscript was improved by helpful reviews from Alan Rubin, Tasha Dunn, and Marina Ivanova, and the editorial expertise of AE Cyrena Goodrich. This work was supported by NASA grants NNX15AH41G to M. W. and NNH19ZDA005K to Z. T. and M. W.
Publisher Copyright:
© 2020 The Meteoritical Society (MET)
PY - 2020/11
Y1 - 2020/11
N2 - The similarities between CV and CK chondrites are so substantial that some studies have argued for a common parent body origin. These similarities also mean that they are susceptible to misclassification as one another. It is, therefore, important to accurately classify CV and CK chondrites to properly compare the properties of the two groups and evaluate the single parent body hypothesis. In this study, we re-evaluate the current classification of Northwest Africa (NWA) 2900 as a CV3 chondrite. Based on chondrule abundance (~13%), average chondrule diameter (1.11 ± 0.67 mm), iron content in chondrule olivine (Fa1 to Fa35 with a peak near ~Fa31) and matrix olivine (Fa33 to Fa36), magnetite abundance (~4 vol%), elemental abundances in olivine (Cr2O3, Al2O3, TiO2, MnO, NiO, and CaO) and magnetite (Cr2O3, Al2O3, TiO2, and NiO), and comparison with previously reported data for CV and CK chondrites, we propose that the classification of NWA 2900 be changed from CV3 chondrite to CK3 chondrite, with characteristics most similar to those of the CK3.8 subtype. We additionally suggest minor modifications to the compositional criteria used to distinguish between CV and CK chondrites and demonstrate that NWA 2900 extends the range of bulk oxygen isotope compositions of CK chondrites.
AB - The similarities between CV and CK chondrites are so substantial that some studies have argued for a common parent body origin. These similarities also mean that they are susceptible to misclassification as one another. It is, therefore, important to accurately classify CV and CK chondrites to properly compare the properties of the two groups and evaluate the single parent body hypothesis. In this study, we re-evaluate the current classification of Northwest Africa (NWA) 2900 as a CV3 chondrite. Based on chondrule abundance (~13%), average chondrule diameter (1.11 ± 0.67 mm), iron content in chondrule olivine (Fa1 to Fa35 with a peak near ~Fa31) and matrix olivine (Fa33 to Fa36), magnetite abundance (~4 vol%), elemental abundances in olivine (Cr2O3, Al2O3, TiO2, MnO, NiO, and CaO) and magnetite (Cr2O3, Al2O3, TiO2, and NiO), and comparison with previously reported data for CV and CK chondrites, we propose that the classification of NWA 2900 be changed from CV3 chondrite to CK3 chondrite, with characteristics most similar to those of the CK3.8 subtype. We additionally suggest minor modifications to the compositional criteria used to distinguish between CV and CK chondrites and demonstrate that NWA 2900 extends the range of bulk oxygen isotope compositions of CK chondrites.
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U2 - 10.1111/maps.13587
DO - 10.1111/maps.13587
M3 - Article
AN - SCOPUS:85096821295
SN - 1086-9379
VL - 55
SP - 2539
EP - 2550
JO - Meteoritics and Planetary Science
JF - Meteoritics and Planetary Science
IS - 11
ER -