open access

https://hdl.handle.net/2115/36659

Phase Relationship of Ca2Mg3Al2Si6Al2O22(OH)2 -Ca2Mg3Fe2^3+Si6Al2O22(OH)2 Join at High Temperature and High Pressure : The Stability of Tschermakite

英語

1978-03

Hokkaido University

Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy

18(3)

339-350

The join tschermakite(Ts) ― ferri-tschermakite(Fts) was studied at temperatures between 750 and 1000℃ under water vapor pressures of 5 to 24 kb. Tschermakite is stable up to 800℃ between approximately 7 and 17 kb. Run products at pressures higher than 17 kb include amphibole associated with clinopyroxene + garnet + quartz + vapor. With increasing temperature at vapor pressures more than about 18 kb, amphibole breaks down to the assemblage, garnet + clinopyroxene + orthopyroxene + quartz + vapor. At lower pressures, the equilibrium mineral assemblage consists of anorthite + orthopyroxene + forsterite + vapor. At 950℃ and 15 kb, no amphibole was found, and run products contain clinopyroxene + orthopyroxene + quartz + vapor. At 1000℃ and 12 kb, a liquid phase is found. No pure ferri-tschermakite could be synthezised at temperatures between 800 and 1000℃, and pressures of 7 to 20 kb. Amphibole, associated with clinopyroxene + orthopyroxene + magnetite + hematite + vapor, is stable up to 850℃ at pressures between 8 and 19 kbar. The solubility limit of Ca2Mg3Fe2^3+Si6Al2O22(OH)2 in tschermakite is 35 mole % at 850℃ and 12 kb.

紀要論文

Version of Record

0018-3474