METAMORPHISM OF EUCRITE METEORITES STUDIED QUANTITATIVELY USING INDUCED THERMOLUMINESCENCE

EUCRITE meteorites 1 are especially important in studies of the early Solar Systems because they are the simplest and most ancient products of a process that was widespread in the inner Solar System 2,3: basaltic volcanism. They are also the meteorites for which there is least doubt of an asteroidal origin 4,5. After volcanism the eucrites experienced a period of metamorphism 6, either inside the asteroid as it cooled from igneous temperatures 7 or on the surface of the asteroid as a result of impact heating 8. Induced thermoluminescence studies provide a new and quantitative means of determining relative metamorphic intensities for these meteorites. Using this technique, we show that the eucrites constitute a continuous metamorphic series and not, as commonly assumed, two groups of metamorphosed and non-metamorphosed meteorites 9. These studies are the first application of the induced thermoluminescence technique to igneous rocks and we suggest that the method may well have application to other basalts.