タイトル無し
スポンサーリンク
概要
- 論文の詳細を見る
The Miyamori-Ohazama district, central Kitakami Mountains, is occupied by the late Paleozoic formations composed chiefly of black shales and fossiliferous limestones. These Paleozoic rocks have been intruded by the Cretaceous Tono granodiorite pluton and undergone contact metamorphism.Three progressive metamorphic zones are recognized on the basis of mineral parageneses in metapelites. Zone I, most of which have been regarded as unmetamorphosed, is characterized by the assemblages of various phyllosilicates alined parallel to slaty cleavages. Zone II is characterized by the appearance of andalusite accompanied by muscovite, biotite, cordierite, garnet and occasionally gedrite. In zone III, sillimanite appears together with K-feldspar, biotite and cordierite. Microscopic observation and X-ray powder diffraction study revealed that metapelites in low-temperature part of zone I consist of the assemblage of paragonite, pyrophyllite, albite and calcite with invariable association of chlorite, muscovite, quartz and carbonaceous matter, suggesting metamorphic grade lower than the greenschist facies. In high-temperature part of zone I, however, porphyroblastic chloritoid, formed by the reaction with pyrophyllite and Fe-rich chlorite, appears in metapelites of lateritic chemical composition (Al2O3 23wt%, FeO/(FeO+MgO)>0.79). The degree of graphitization of carbonaceous matter in the metapelites progressively increases from zone I to zone III, showing a continuous thermal structure around the Tono granodiorite pluton. Judging from the graphitization-profile, all the assemblages mentioned above are considered to have been equilibrated under the thermal structure controlled by the Tono granodioritic intrusion.
- 日本鉱物科学会の論文
日本鉱物科学会 | 論文
- シリケイトメルト中の水の拡散
- 岡山市北西部, 日近花崗閃緑岩体の岩石記載および全岩化学組成
- 高エネルギー陽子マイクロビームによる鉱物中の水素定量分析法の開発
- 日本海竹島海山(仮称)のかんらん岩捕獲岩の成因とその意義
- 高輝度 高指向 連続光・直線偏光の単結晶X線回折への恩恵