Chemical zoning in pristine objects of chondrites as archive of the thermal and redox history in the early solar nebula and planetesimals

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A number of pristine minerals have been identified in meteorites that are thought to be formed by condensation from gas in the protoplanetary accretion disk during the first few million years of the solar system. The detailed mineral chemistry and any chemical zoning preserved provide a unique archive of their thermal history. We plan to identify the various thermal events (e.g. transient heating events in the solar nebula and the thermal metamorphism on the parent body of the host meteorite) and infer the associated peak temperatures and cooling rates from the zonings of major, minor, and trace elements in these pristine minerals by means of diffusion modeling. The elaboration of the complex sequence of thermal events is now possible due to the recently published set of accurate diffusion data, recently established modeling techniques, and finally, the sensitivity of different elements in a given mineral to different temperature ranges. The latter aspect is related to the strongly different mobility of various elements within a mineral. The derived thermal histories would significantly improve our understanding of the physical conditions in the solar nebula as wells as in small planet like objects.