Dating of non carbonaceous materials

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Of course, they do contain chondrules that are the products of heating in the proto-solar disk, but the metal-rich carbonaceous chondrites themselves were not heated significantly.

Photograph of a polished slab of the CB chondrite Gujba [ Data Link from the Meteoritical Bulletin Database.

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Darker objects (SO) are chondrules, in this case containing rapidly-crystallized, skeletal-olivine (SO) chondrules.In addition, other features, such as nitrogen isotopic composition and the relatively young ages of chondrules in metal-rich carbonaceous chondrites—5 million years after CAIs formed compared to about 3 million years for chondrules in other chondrite types—also point to their primitive, low-temperature origins (discussed further below).The startling observation made by Eli Van Kooten and co-workers is that the Cr and Mg isotopic compositions of metal-rich carbonaceous chondrites and the components in them (chondrules, pieces of primitive rock) lie along a line from the CI chondrite point on the inner Solar System line (shown above) to the predicted isotopic composition of materials that were not processed in the solar nebula and were free of Al when they formed (see diagram below).In addition, one group of metal-rich carbonaceous chondrites, the CR chondrites, contain the highest abundance of pre-solar grains among the carbonaceous chondrites.Cosmochemists identify pre-solar grains by their unusual (compared to most Solar System materials) isotopic compositions of elements such as carbon, silicon, and titanium.

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