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- Title
Geochemical and oxygen isotope perspective of a new R chondrite Dhofar 1671: Affinity with ordinary chondrites.
- Authors
Ali, Arshad; Nasir, Sobhi J.; Jabeen, Iffat; Al Rawas, Ahmed; Banerjee, Neil R.; Osinski, Gordon R.
- 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.
- Subjects
RARE earth metal analysis; CHONDRITES; PYROXENE; OLIVINE; MICROPROBE analysis
- Publication
Meteoritics & Planetary Science, 2017, Vol 52, Issue 9, p1991
- ISSN
1086-9379
- Publication type
Article
- DOI
10.1111/maps.12903