EXPERIMENTAL INVESTIGATION OF FACTORS CONTROLLING THE COMPOSITION OF GLASSES FROM THE LUNAR REGOLITH

Abstract

This paper presents the results of experiments imitating shock melting, spraying, and mixing of melts of a chondritic projectile and targets that model lunar highland and mare rocks. The analysis of glass spherules demonstrated that their composition was controlled by (a) fusion in varying proportions of chemically contrasting materials of the projectile and target and (b) selective vaporization of melt components. The selective vaporization is manifested in a decrease in the concentrations of moderately volatile Si and, especially, Fe in glass. On average, the concentration of iron decreased by a factor of 2. Such significant Fe losses occurred within ∼0.01 s. Iron vaporization resulted in an increase in the Mg/(Mg + Fe) ratio of glass. A comparison of the petrochemical characteristics of the experimental glasses with the pristine lunar glasses of volcanic origin suggested that the compositions of the latter could be obtained in an impact process.