Systematics of Ti isotopes in carbonaceous chondrite whole‐rock samples

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Abstract
Titanium isotopic compositions in whole‐rock samples are reported for meteorites from all four carbonaceous chondrite classes. Characteristic isotopic patterns are derived for each class, since meteorites in a given class usually, though not always, give the same pattern. No anomalies are resolved at the 47/46 and 48/46 ratios, but small 50 excesses are prevalent [ε(50/46) mean values are CI=+1.0±0.8; CM=+2.4±0.6; CO=+3.0±0.5; CV=+3.3±0.5]. Among the three classes where Ti anomalies are clearly present, the mean values for the 50 excesses are the same within the uncertainties. In contrast, the CI class gives just a hint of a 50 excess. Available data, including analyses of Murchison (CM) density separates, suggest that anomalous Ti is not confined to phases in refractory inclusions. Kakangari, a petrologically and chemically peculiar meteorite, shows a clear deficit of 50, thereby supporting a previous suggestion that it is a unique carbonaceous chondrite.

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