Geochemical and oxygen isotope perspective of a new R chondrite Dhofar 1671: Affinity with ordinary chondrites

Arshad Ali, Sobhi J. Nasir, Iffat Jabeen, Ahmed Al Rawas, Neil R. Banerjee, Gordon R. Osinski

Research output: Contribution to journalArticle

Abstract

Dhofar 1671 is a relatively new meteorite that previous studies suggest belongs to the Rumuruti chondrite class. Major and REE compositions are generally in agreement with average values of the R chondrites (RCs). Moderately volatile elements such as Se and Zn abundances are lower than the R chondrite values that are similar to those in ordinary chondrites (OCs). Porphyritic olivine pyroxene (POP), radial pyroxene (RP), and barred olivine (BO) chondrules are embedded in a proportionately equal volume of matrix, one of the characteristic features of RCs. Microprobe analyses demonstrate compositional zoning in chondrule and matrix olivines showing Fa-poor interior and Fa-rich outer zones. Precise oxygen isotope data for chondrules and matrix obtained by laser-assisted fluorination show a genetic isotopic relationship between OCs and RCs. On the basis of our data, we propose a strong affinity between these groups and suggest that OC chondrule precursors could have interacted with a 17O-rich matrix to form RC chondrules (i.e., ∆17O shifts from ~1‰ to ~3‰). These interactions could have occurred at the same time as “exotic” clasts in brecciated samples formed such as NWA 10214 (LL3–6), Parnallee (LL3), PCA91241 (R3.8–6), and Dhofar 1671 (R3.6). We also infer that the source of the oxidation and 17O enrichment is the matrix, which may have been enriched in 17O-rich water. The abundance of matrix in RCs relative to OCs, ensured that these rocks would be apparently more oxidized and appreciably 17O-enriched. In situ analysis of Dhofar 1671 is recommended to further strengthen the link between OCs and RCs.

Original languageEnglish
Pages (from-to)1991-2003
Number of pages13
JournalMeteoritics and Planetary Science
Volume52
Issue number9
DOIs
Publication statusPublished - Sep 1 2017

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ordinary chondrite
chondrites
oxygen isotopes
chondrite
oxygen isotope
affinity
isotopes
chondrule
matrix
olivine
matrices
pyroxene
volatile element
clast
meteorite
zoning
rare earth element
laser
fluorination
meteorites

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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Geochemical and oxygen isotope perspective of a new R chondrite Dhofar 1671 : Affinity with ordinary chondrites. / Ali, Arshad; Nasir, Sobhi J.; Jabeen, Iffat; Al Rawas, Ahmed; Banerjee, Neil R.; Osinski, Gordon R.

In: Meteoritics and Planetary Science, Vol. 52, No. 9, 01.09.2017, p. 1991-2003.

Research output: Contribution to journalArticle

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