Oxygen isotope systematics of chondrules in the Paris CM2 chondrite: indication for a single large formation region across snow line.

In-situ oxygen three-isotope analyses of chondrules and isolated olivine grains in the Paris (CM) chondrite were conducted by secondary ion mass spectrometry (SIMS). Multiple analyses of olivine and/or pyroxene in each chondrule show indistinguishable ΔO values, except for minor occurrences of relict olivine grains (and one low-Ca pyroxene). A mean ΔO value of these homogeneous multiple analyses was obtained for each chondrule, which represent oxygen isotope ratios of the chondrule melt.

Oxygen isotope systematics of chondrules in the Murchison CM2 chondrite and implications for the CO-CM relationship.

High-precision oxygen three-isotope measurements of olivine and pyroxene were performed on 29 chondrules in the Murchison CM2 chondrite by secondary ion mass spectrometry (SIMS). The oxygen isotope ratios of analyzed chondrules all plot very close to the primitive chondrule minerals (PCM) line. In each of 24 chondrules, the olivine and/or pyroxene grains analyzed show indistinguishable oxygen isotope ratios.