Premium
Geochemical and oxygen isotope perspective of a new R chondrite Dhofar 1671: Affinity with ordinary chondrites
Author(s) -
Ali Arshad,
Nasir Sobhi J.,
Jabeen Iffat,
Al Rawas Ahmed,
Banerjee Neil R.,
Osinski Gordon R.
Publication year - 2017
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12903
Subject(s) - chondrule , chondrite , pyroxene , olivine , ordinary chondrite , porphyritic , geology , meteorite , isotopes of oxygen , matrix (chemical analysis) , geochemistry , parent body , carbonaceous chondrite , chemistry , plagioclase , breccia , mineralogy , analytical chemistry (journal) , astrobiology , quartz , environmental chemistry , physics , paleontology , chromatography
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 ( RC s). Moderately volatile elements such as Se and Zn abundances are lower than the R chondrite values that are similar to those in ordinary chondrites ( OC s). 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 RC s. 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 OC s and RC s. 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 17 O‐rich matrix to form RC chondrules (i.e., ∆ 17 O 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 ( LL 3–6), Parnallee ( LL 3), PCA 91241 (R3.8–6), and Dhofar 1671 (R3.6). We also infer that the source of the oxidation and 17 O enrichment is the matrix, which may have been enriched in 17 O‐rich water. The abundance of matrix in RC s relative to OC s, ensured that these rocks would be apparently more oxidized and appreciably 17 O‐enriched. In situ analysis of Dhofar 1671 is recommended to further strengthen the link between OC s and RC s.