巻号一覧
80 巻, 9 号
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その1岩石記載と内部構造田中 忍, 丸山 孝彦1985 年 80 巻 9 号 p. 371-381
発行日: 1985/09/05
公開日: 2008/08/07
ジャーナル フリーAn examination is made on field occurrnce, petrographic character and inner structure of the Funatsu granitic complex, located in the Funatsu area in the Hida Mountains. This complex consists of three types of granitic rock: Shimonomoto, Nakasawa and Funatsu types in the order of emplacement. Since the Shimonomoto type spans from medium-grained biotite-hornblende quartz diorite to medium-grained bitotite adamellite, it is subdivided into three facies according to their lithology: Kanekido, Kuwasaki and Ikenoo. The rockfacies change of the Shimonomoto type is clear and shows normally zoned pluton. The Nakasawa type consists mainly of fine-grained hornblende-bearing biotite adamellite, and the Funatsu type consists of medium- to coarse-grained biotite adamelite.
Granitic rocks in this complex have schistose structure defined by mineral orientation with varied strength. This structure may have been formed by the internal movement of magmas during emplacement. According to our field survey of this structure, the Shimonomoto and Funatsu types are found to have some basin and some dome structures, respectively. These structural difference may be related to the solidifying depth of each magma.抄録全体を表示PDF形式でダウンロード (969K) -
奥井 明彦1985 年 80 巻 9 号 p. 382-397
発行日: 1985/09/05
公開日: 2008/08/07
ジャーナル フリーThe Hida metamorphic rocks in the upper Katakai river area are composed of the eastern fine-grained Unazuki schists and western coarse-grained Hida gneisses. The two, unites are separated by a mylonite zone which trends N-S direction and has a width of 300-500m, and are intruded by the Funatsu granitic rocks of the early Jurassic age. Augen gneiss occurs in the most western part of metamorphic rocks along the granite body.
The calcareous rocks in both units are considered to be polymetamorphosed by the granitic intrusion. They are classified into two groups: group A contains coexisting calcite and guartz and group B contains wollastonite. The rocks of group A are subdivided into three mineral zones: zone 1 is characterized by coexistence of plagiocalse, calcite and quartz, zone 2 by presence of grossular and zone 3 by presence of vesuvianite. The Group B rocks are subdivided into two zones: zone 4 is characterized by coexistence of calcite and grossular, and zone 5 by coexistence of vesuvianite and wollastonite. Rocks of zone 3 occur characteristically along the mylonite zone and augen gneiss zone, and those of zones 4 and 5 in the vicinity of the granitic contact.
The comparison of the mineral assemblages of five zones on the isobaric T-XCO20 diagram in the CaO-Al2O3-MgO-SiO2-H2O-CO2 system suggests that: (1) the rocks of group A have metamorphosed at almost the same temperature, but XCO2, in the equilibrium fluid decreases progressively from zone 1 to zone 3; (2) the metamorphic temperature for group B is higher than that for group A; (3) fluids in the rocks of zone 5 are H2O-rich than those of zone 4. The characteristic distribution of mineral assemblages in caclareous rocks is interpreted in terms of the regional infiltration of H2O-rich fluid through the mylonite zone and the augen gneiss zone during the granitic intrusion.抄録全体を表示PDF形式でダウンロード (2115K) -
周藤 賢治, 八島 隆一1985 年 80 巻 9 号 p. 398-405
発行日: 1985/09/05
公開日: 2008/08/07
ジャーナル フリーHortonolite andesites of middle Miocene age have been found in the Daigo district of the northeastern part of Ibaraki Prefecture, Northeast Japan. These andesites (the Nantaisan andesites) occur as subaqueous autobrecciated lavas and massive lavas which are also erupted in water bottom. The Nantaisan andesites are mostly aphyric, but some andesites contain small amount of phenocrysts of hortonolite, ferrohypersthene and plagioclase. An andesite specimen has ferropigeonite, hortonolite and ferrohortonolite in the groundmass. Ferropigeonite of the groundmass is lower in Fe/Mg ratio than the coexisting hortonolite and ferrohortonolite. The latter minerals bear no reaction relation to the former mineral. Bulk chemical compositions of the Nantaisan andesites are similar to those of icelandites from eastern Iceland. Differences in petrologic characters in the Quaternary and Miocene tholeiitic volcanic rocks occurring near the Quaternary volcanic front and its neighbouring Miocene volcanic field in the northeast Japan arc are described in the paper.抄録全体を表示PDF形式でダウンロード (1875K) -
宮地 六美1985 年 80 巻 9 号 p. 406-409
発行日: 1985/09/05
公開日: 2008/08/07
ジャーナル フリー九州外帯の4花崗岩体から,10試料の花崗岩について,ジルコンのフィッシ・トラック年代が決定された。大隅花崗岩, 13.6±1.Om.y.(6年代値の平均),高隅山花崗岩,12.9±1.Om.y.,市房山花崗岩,12.0±0.9m,y.,紫尾山花崗岩,12.5±1.1m.y.(2年代値の平均)。これらの年代は,4花崗岩体がほとんど同時に冷却したことを示している。
又,大隅花崗岩からはアパタイトの年代がpopulation法で決定され,12.0±2.6m.y.という値を得た。この年代はジルコンのフィッション・トラック年代とほとんど同じであり,このことから,大隅花崗岩は約12m.y.前に貫入が完成し,その冷却は非常に早かったことを物語っている。抄録全体を表示PDF形式でダウンロード (225K)
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