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Volume 70, Issue 9
Displaying 1-4 of 4 articles from this issue
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MORIHIRO AOKI, HIROSHI ABE1975 Volume 70 Issue 9 Pages 295-304
Published: September 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe specimens of chabazite, chabazite plus montmorillonite and chabazite plus low-cristobalite were subjected to alteration in sodium carbonate solution under the condition of 150°-300°C and 30-110kg/cm2 for 5-20 days. In the reaction between chabazite and sodium carbonate solution, analcime and calcite has readily formed at 150°-200°C in every treatments. Under the condition of 300°C in 1/8 molar solution, analcime was still, formed with calcite. However, at 300°C in 1 molar solution, cancrinite was newly formed together with calcite and thermonatrite. By the effect from the addition of low-cristobalite, pectolite was progressively formed at 300°C in 1 molar and 1/8 molar solutions with an increasing reaction time. The mol. ratios of SiO2 obtaining by the measurements of 2θAnalcime (639)-2θsilicon cash (331) (CuKa) from synthesized analcime varied from 3.8 to 6.0. The analcime compositions are controlled by the relative concentrations of sodium and silica in the reaction system.View full abstractDownload PDF (1078K) -
MICHIO TAGIRI, HITOSHI ONUKI, TEIJI YAMAZAKI1975 Volume 70 Issue 9 Pages 305-314
Published: September 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe argillaceous xenoliths within the andesitic lavas of the N??jo-san and Amatakiyama districts were recrystallized successively by the thermal effects of the magma. The mineral assemblages of these xenoliths can be classified into the large-grained and fine-grained groups. The former is subdivided into the staurolite-bearing and staurolitefree assemblages. The staurolite-bearing parageneses of the minerals can be regarded as the amphibolite or pyroxene hornfels facies and the stauro lite-free ones composed of minerals with large grain-size belong to the pyroxene hornfels facies. Such fine-grained parageneses as the corona texture and the breakdown products of garnet were formed under the conditions of the pyroxene hornfels or sanidinite facies. From the progressive change of mineral facies and the distinct descrepancy of grain-size between the large mineral assemblages and fine mineral ones, it is possible to consider, roughly estimating, that the former indicates the stage of contact metamorphism and the latter the stage of pyrometamorphism.View full abstractDownload PDF (2546K) -
Masaharu Yamada, Hideo Ishikawa1975 Volume 70 Issue 9 Pages 315-321
Published: September 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe Koshiki Islands are located at southwest Kyushu, and are underlain by the sedimentary rocks belonging to the Himenoura Group (Upper Cretaceous) and Paleogene Tertiary, and granitic rocks intruded into them in Miocene age.
The Himenoura Group, forming a northeast-plunging synclinorium, is more than 3, 600meters thick, and is stratigraphically divided into six units, provisionally named A to F by K. Tanaka and Y. Teraoka (1973). Division B is more than 1, 200meters thick and graphite deposits are found in the phyllitic slates at the lowest part of it, subdivision B1 in the Shimokoshiki-Jima.
The graphite deposits, the new occurrences in the Upper Cretaceous sediments of Japan, occur in the area about 2km west of Katanoura. There are a few ore bodies in this area, croping intermittently out about 300meters length. Three main ore bodies among them are named the Suzugaura 1 and 2, and Suzugasaki, and these ore bodies are lenticular shape with several meters length and 1 meter thick.
The graphite ore consists mainly of fine-grained crystalline graphite and quartz, and subsequently of sericite, chlorite, and plagioclase. The average values for carbon in the ores of these ore bodies range from 30 to 56 percent C.
The process of the formation of the graphite deposits in this area is considered as follow:
1) Upper Cretaceous: Sedimentation of the Himenoura Group {Sandstone and slate dominant with carbonaceous deltaic sediments in basal part (B1).
2) Late Cretaceous to Paleogene Tertiary: Himenoura Movement {Slight concentration of carbonaceous materials and them slight graphitization.
3) Miocene: Participation in aplites related with granodiorite intrusion {Migration, concentration and crystallization on of carbonaceous materials. Formation of graphite deposits.View full abstractDownload PDF (1062K) -
Yoshikuni Hiroi1975 Volume 70 Issue 9 Pages 322-333
Published: September 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe staurolite-bearing rocks of the Hida metamorphic belt exposed in the area of the lower course of the Kurobe River are classified into the black phyllitic, silvery schistose and massive types. Characteristically they contain one or more of Al2SiO5 minerals besides staurolite. Staurolite in these rocks always show a more or less sponge-like dissolution texture. From the textural evidences and paragenetic relations of the minerals in the selected specimen of each type, it is concluded that metamorphism occurred two times, at least, in this area. The former metamorphism corresponds to the medium-pressure type. Staurolite, garnet, kyanite and sillimanite were formed by this older metamorphism. The later event is the lower-pressure series of metamorphism which formed andalustie and fibrolite. The younger metamorphism accompanied by intense deformation and local metasomatism was caused by the Funatzu plutonic complex during the Late Paleozoic to Early Mesozoic age.View full abstractDownload PDF (2773K)
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