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Volume 39, Issue 1
Displaying 1-5 of 5 articles from this issue
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Kiyohiko Ishii, Yoshio Ueda, Mitsuo Shimazu1955 Volume 39 Issue 1 Pages 1-10
Published: February 01, 1955
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSIna district is located at the northernmost of the Ryoke zone and mainly composed of Ryoke-granites, Ryoke-metamorphics and non-metamorphic sediments. The eastern margin of this district along the median tectonic line is composed of the Kashio Gneiss. These complex grade into non-metamorphic sediments toward west. The Ryoke zone of this area mainly comprises metamorphic rocks, granites and seine migmatites. The Ryoke metamorphic rocks are composed of schistoe hornfels, mica schists, banded gneisses, meta-diabases, quartz schists and crystalline limestones. From mode of occurrence and petrographic feature, migmatites of this area can be divided into the following three rock types.
1 Schistose fine grained biotite granite and granitic gneiss.
2 Gneissose granite.
3 Fine grained two mica migmatite.
Schistose coarse and medium grained hornblende-biotite grancdioritee are widely distributed in the southern part. Medium and coarse grained biotite granites occur in the northern part with the form of stock. Kashio Gneiss is composed of porphyritic biotite gneiss and hallefiintaic gneiss. The relation between metamorphism, granitization, and granite intrusion may be explained as follows:
1. The Ryoke metamorphics have been introduced by regional metamorphism and some of them at the eastern part have been passed into the migmatite of the first type.
2. After the metamorphism and granitization, metamorphic rocks were intruded by schistose coarse grained nornblende biotite granite. As a result of tne intrusion, some of invaded rocks have been locally migmatized to the second and third type.View full abstractDownload PDF (709K) -
Akiho Miyashiro1955 Volume 39 Issue 1 Pages 10-15
Published: February 01, 1955
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSA pyralspite garnet from a sericite-chlorite-schist at Oyahana, Titibu, was analysed as shown in Table 3. It is mainly composed of spessartine and almandine molecules. The MnO content of the pyralspite, is as high as 18.03%, while that of the host rock is about 0.6%(Table2). Petrological problems related to the pyralspite are discussed.View full abstractDownload PDF (334K) -
Ichikazu Hayase, Tokumichi Tsutsumi1955 Volume 39 Issue 1 Pages 15-21
Published: February 01, 1955
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSThe radioactive order of rocks, namely, of the lamprophyre dykes in Kitashirakawa granite, Kyoto City, and of the Tertiary mudstone1) common in Nachi District, Wakayama Prefecture was studied autoradiographically with ET nuclear emulsion: the average alpha track number per centimeter square was found per day 7.28±1±0.34 in the former and 15.98±1.17 in the latter; these two values were compared with those of some other rocks.View full abstractDownload PDF (416K) -
Stannite and borniteNoritosi Yamae1955 Volume 39 Issue 1 Pages 21-30
Published: February 01, 1955
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESS -
Mitsuo Shimazu1955 Volume 39 Issue 1 Pages 30-42
Published: February 01, 1955
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSThe Tabashine adamellite mass intruded into the black slates, conglomerates of the Toyoma series and basic volcanics probably of Cretaceous. As the results the country rocks have been metamorphosed into various kinds of hornfels. From the mode of occurrence and petrographical feature, this mass can be divided to the following four rock types; Tabashine, Aikawa, Togaku and Kuromori types.
Tabashine type is chiefly adamellite. Aikawa and Togaku types are granodiorite. Kuromori is quartz diorite.
All but Kuromori type have dark inclusions, which are similar to the Kuromori type in petrographical properties. All rock types have nearly same essential constitutent minerlas, i. e., plagioclase, orthoclase, quartz, biotite, hornblende, and augite and/or hypersthene.
Most of plagioclases are oligoclase, and orthoclases are perthitic. γ of biotite vary from 1.645 to 1.660.
Some consideration on the petrogenesis is given. The hybrid phenomer a between the granitic magma and the diabasic rock of this area have been studied by Yamada (1939). Contrary to his argument, it is to be noted that the effect of such hybridization on the basification of granitic rock is less significant than that between granitic magma and basic rock (probably two pyroxene gabbroic rock) at a deeper zone of the crust.
This original granitic magma may be adamellitic in composition. Kvrcmori type and dark inclusion may be the products of such phenomenon, and granodiorites as Aikawa and Togaku type may have been resulted when hybridization proceeded further. When compared with the Orikabe and Hirota masses to the east, they have closely similar geological situation and petrographical properties to the Tabashine mass.View full abstractDownload PDF (835K)
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