@article{oai:nipr.repo.nii.ac.jp:00004486,
 author = {Nagahara, Hiroko and Kushiro, Ikuo},
 journal = {Proceedings of the NIPR Symposium on Antarctic Meteorites},
 month = {Oct},
 note = {P(論文), Vaporization experiments in the system plagioclase (An_<77>)-hydrogen were carried out at temperatures between 1200 and 1475℃ and in the pressure range from 10^<-9> to 10^<-4> bar. After partial vaporization, originally homogeneous plagioclase became zoned with increase of CaO and decrease of Na_2O from core to rim. The compositional change plotted on Si-Na-Ca, Al-Na-Ca, and Al-Na-Si diagrams revealed that plagioclase vaporized incongruently to form a gas with an atomic ratio close to Si : Al : Na=1 : 1 : 1 and non-stoichiometric residue over wide ranges of total pressure and oxygen fugacity. Increase of total pressure, which corresponds to increase of hydrogen pressure in the present experiments, enhanced vaporization; the Na_2O content at the surface of residue decreased and the depth of the Na_2O-depleted zone from the surface to the interior of the charges increased. Hydrogen may play the role of catalyst for the vaporization reaction. Another explanation for the role of hydrogen is that plagioclase reacts with carbon from the sample container and hydrogen to form a gas, carbon monoxide or dioxide, and methane. Non-stoichiometric composition of plagioclase in mare basalts may be due to vaporization in the high vacuum of the lunar surface.},
 pages = {235--251},
 title = {Vaporization experiments in the system plagioclase-hydrogen},
 volume = {2},
 year = {1989}
}