"S.Singletary" wrote: > They are indeed complicated little beasties.
CAIs are characteristically enriched in refractory elements and cannot only be found in carbonaceous chondrites but also in primitive ordinary, enstatite, and K chondrites. Their isotopic anomalies originated in nucleosynthesis processes in stars, novae, and supernovae. Petrological classification of CAIs: Type A, type B, and type C => petrological diversity reflects difference in formation temperature (melted or not) Chemical classification of CAIs: Groups I�V => chemical diversity reflects the condensation and/or evaporation history. The two classifications are independent which suggests the high temperature event responsible for texture might differ from that which caused evaporation/condensation. Two types of rims of CAIs: - fine-grained rims: a mixture of several mineral species - Wark�Lovering rims: series of mineral layers, suggesting different formation process(es). Wark�Lovering rims have average thickness of 50 �m, where spinel with perovskite inclusions, melilite or its alteration pro- ducts (anorthite, nepheline, sodalite, grossular and phyllo- silicates), and diopsidic pyroxene successively cover the inclusions. Reference: NAGAHARA H. (2001) Flash heating of CAI-rich inclusions (MAPS 36-8, 2001, p. 1011, From the Editors). Cheers, Bernd ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
