泥質片麻岩におけるスピネル生成部分融解反応 : 記載岩石学的および合成実験的アプローチ

概要

論文の詳細を見る
Petrography of two metatexite specimens from the Abukuma and Ryoke metamorphic belts in Japan suggests that spinel was produced together with cordierite and granitic melt by a partial melting reaction that consumes sillimanite and biotite. Reproductive experiments were performed at a pressure of 200 MPa and temperatures ranging from 700 to 950°C. The starting material was uncrushed Takanuki pelitic gneiss containing abundant biotite and sillimanite without spinel. From the experimental results we confirm that the following spinel-producing partial melting reaction takes place commonly at 800°C and higher temperatures. Sillimanite+biotite+plagioclase+quartz±H2O→spinel+cordierite+granitic melt.Of particular importance is that spinel occurs only within silica-poor portion of the granitic melts produced at temperatures lower than 900°C. On the other hand, spinel is in direct contact with quartz in the run products at 950°C, being in good harmony with the petrogenetic grid of Vielzeuf and Holloway (1988). Thus it can be pointed out that SiO2-undersaturated domains are easily formed locally during partial melting due to kinetic reasons and/or to the complete consumption of quartz by the melting reactions in pelitic rocks.
日本鉱物科学会の論文
2002-03-30