Classification and the Oxygen (O) 3-Isotope Plot
Channel: Dominik Hezel
Date: 2019-10-21

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Meteorites differs significantly in their oxygen isotope composition. This is therefore used as a classification characteristic. Meteorites of the same group can, however, scatter across a significant range of O-isotope compositions. Components of a meteorite, such as chondrules or CAIs, also scatter across significant range of O-isotope compositions. It is striking that certain meteorite groups, but also components such as chondrules or CAIs plot along a mass-independent line with a slope close to 1. The solar wind has a highly 16O-rich composition, close to that of CAIs. This likely is the original composition of our solar system, and the presently observed composition in meteorites and their components, as well as the composition of other planetary bodies such as the Earth, the Moon, or Mars developed in subsequent processes. One possibility is mixing of material that initial had a similar composition as the Sun, with a highly 16O-rich component, as it is measured in ›astrosilicates‹. These have delta17/16O compositions around +150 ‰, and plot along the extension of the around slope 1 fractionation line.