JMSSJ On-line

JMSSJ On-line, Vol. 48 (2000) No. 5, pp. 298-302

Isotope Mass Fractionation Process Caused by Evaporation and Condensation in the Primordial Solar Nebula		>> Full Text PDF >> References
Chiaki UYEDA^* ^† This paper is dedicated to the memory of the late Professor Takekiyo MATSUO. ^* ¡þ

The isotope mass fractionations of various refractory inclusions observed in the primitive materials as well as its estimated thermal origin are reviewed, which are generally inconsistent with the origins estimated by other procedures. The temperature dependence was studied for the mass fractionation of condensates produced form Mg-silicate gas in the evaporation-condensation experiment. The ²⁶Mg/²⁴Mg values of the condensates with respect to the starting material fractionated both in the heavy and light isotopes. The theoretical relationship of the condensates showed good agreement with the experimental values. It has revealed that the amount of mass fractionation cannot be a simple indicator to judge whether the inclusion was a condensate or an evaporation residue. Rayleigh mass fractionation occurs under a restricted condition. It is necessary to know the actual fractionation coefficient in the nebula, in order to discuss the relationship between the mass loss of a depleted element and its isotope fractionation in the primitive planetary bodies in terms of the Rayleigh distillation process.

Key words: Isotope mass fractionation, Primitive materials, Meteorites, Evaporation, Condensation