Dynamic crystallization characteristics of enstatite chondrite chondrules

Although the chemical properties of enstatite and ordinary chondrites are distinctly different, they both contain chondrules with a similar array of textures. This similarity suggests like origins. Textural studies using chondrule compositions from ordinary chondrites suggest that these chondrules have an igneous origin: either by crystallization from melts or from partial melts of crystalline material. In contrast, the cathodoluminescence (CL) properties of the enstatite from enstatite chondrites were interpreted to mean that mechanical aggregation played an important part in their formation. An alternative interpretation of these CL properties, however, suggests that variations in the minor element content of the enstatite, a probable result of igneous fractionation processes, could also produce different CL colors. An attempt was made to evaluate the two models by performing dynamic crystallization experiments on an average enstatite chondrule composition and by looking at the resultant CL. The textures grown on experimentally crystallized E-chondrite melts confirm that formational processes are similar to those for the ordinary chondrites with the obvious exception of the oxidation state.