| Abstract: | Abstract— The observed textures and chemistry of calcium‐aluminum‐rich inclusions (CAIs) are presumed to be the culmination of a series of repeated heating and cooling events in the early history of the solar nebula. we have examined the effects of these heating/cooling cycles experimentally on a bulk composition representing an average type b cai composition by varying the nature of the starting material. Although the most recent and/or highest temperature event prior to incorporation into the parent body dominates the texture and chemistry of the CAI, prior events affect the phase compositions and texture. We have determined that a prior low‐temperature event (simulated by heating the sample to 1275 °C and cooling slowly) increases the likelihood of anorthite crystallization in subsequent higher temperature events. A prior high‐temperature event that produced dendritic melilite (simulated by heating the sample to 1550 °C and cooling rapidly) results in melilite that shows evidence of rapid crystallization in subsequent lower temperature events. The addition of Pt powder to the starting material appears to enhance the ability of anorthite to nucleate from this composition and increases the number of melilite crystals present in samples that crystallize euhedral melilite. |
