CaMgSi_2O_6-CaFeAlSiO_6-CaTiAl_2O_6系におけるTiに富むファッサイト質輝石(<特集>造岩鉱物研究の現状と展望-地団研第33回総会鉱物学ミニシンポジウム-)

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Phase equilibria in the join CaMgSi_2O_6-CaFe^<3+>AlSiO_6-CaTiAl_2O_6 have been determined in air at 1 atm by the ordinary quenching method. At subsolidus temperatures the single phase field of clinopyroxene extends up to 19 wt. %. Even in the field of clinopyroxene + perovskite, the TiO_2 content in clinopyroxene continues to increase and attains 9.2 wt. % TiO_2 with 24.8 wt. % Al_2O_3. An interesting fact is that unusual clinopyroxenes which contain more A1IV than Silv are present in the CaFeAlSi0_6-rich region. At subliquidus temperatures the liquid is richer in Ti, Al, and Fe^<3+> than the coexisting pyroxene. The clinopyroxenes coexisting with liquid contain less TiO_2, A1_20_3 and Fe_20_3 than those crystallized at subsolidus temperatures. The system CaMgSi_2O_6-CaFe^<3+>AlSiO_6-CaTiAl_20_6 is relevant in evaluating the crystallization trend of clinopyroxenes in udersaturated alkalic rocks.
地学団体研究会の論文
1982-03-25