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Volume 57, Issue 668
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Toshimasa Tanai1951 Volume 57 Issue 668 Pages 157-170
Published: May 31, 1951
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSDans ce district, la systeme tertiaire houillere se developpe couvrant la base granodioritique, et comprend beaucoup de materiaux pyroclastiques et de roches extrusives., 1) De cote occidentale de la chaine montagnes, ou peut la diviser en deux formations: formation de Sanze a l'inferieur et celle de Kamigo au superieur, de cote orientale affleure la formation tres tufacee de Kamigo qui semble equivalente de celle de Sanze., L'auteur decris en detaille de la geologie generale de ce district, surtout de la stratigraphie et de la petrographie du "tuf vert" proprement-dit., 2) Affectee du plissement et du mouvement de faille la structure de ce district est plus ou moins compliquee., L'echelle des failles est plus large en direction de NNE-SSO, d'ailleur celles de la premiere direction sont accompagnees de plis, paralles a ses axes., 3) L'ordre des volcanismes remarquables sont le suivant: andesite a pyroxene→rhyollite→roches granitiques→andesite a pyroxene→roches basaltiques→andesite a deux pyroxenes., 4) Des fossiles mollusques et vegetaux sont abondamment obtenues dans cas formation quiappartiennent a la miocenc inferieure ou moyenne., L'auteur presentera la description detaillee de ces fossiles a une autre occasion.,View full abstractDownload PDF (1853K) -
Jitsutaro Takubo, Tateo Ueda, Shinichi Nishimura1951 Volume 57 Issue 668 Pages 171-175
Published: May 31, 1951
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe present research was carried out with betafite accompanied with pegmatites distributed in chin-chou ( ?? ?? ) region, South Manchuria., The Specimens were donated by Dr., H., Kuno and Mr., Y., Nonaka, whose kindness is gratefully acknowledged., The external crystal form is combined with octahedron and rhombic dodecahedron., The chemical analysis showes that the composition of the mineral is nearly corresponds to a general formula XZ 3 (O, OH) 9 which was proposed by F., Machtschki for the minerals of betafite group., X-ray studies were carried out with the specimens of original and ignited mineral; the indexed powder pattern data of the former coincide with those of anatase and the latter with rutil and pyrochlore., By using its contents of Pb, U and Th, the age of this mineral is determined as 7., 55×108 years.,View full abstractDownload PDF (638K) -
George Kojima1951 Volume 57 Issue 668 Pages 177-190
Published: May 31, 1951
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe stratigraphical and structural analysis of crystalline schist region must be based on the mapping according to original rock-species from which the crystalline shcists were formed., The identification of original rock-species is sometimes very difficult owing to the metamorphic differentiation under allochemical conditions., The crystalline schists of Central Sikoku belong to the chlorite-zone or the green-schist facies of metamorphism of a regional scale., They can be divided lithologically into the following groups and formations from the lower to the upper (Figs., 2 and 3): 1., Nisiiya Group: The component members are mainly siliceous black-schists, interbedded with several thin beds of green-schists and pinkish or greenish quartz-schists., It is supposed that the group includes some acid igneous rocks as quartz-porphyries, granite-porphyries, granites, quartz-diorites, etc., which are now represented by the pebbles in conglomerate-schists in the Oboke-Formation (This Journal, Vol., 56, No., 658, 1950, pp., 366-367)., The whole thickness of the group exceeds 800m., 2., Yosinogawa Group: 1) The lower sub-group is divided into the lower: Oboke Formation and the upper: Kawaguti Formation., Oboke Formation: The component members are sandstone-schists interbedded with thin beds of black-schists., In the middle and upper parts there are intercalated beds of conglomerate-schists 1-40m., thick., The whole thickness of the formation exceeds 1500m., The lower limit of the formation is concealed beneath the Oboke anticline., Kawaguti Formation: This formation is mainly composed of black-schists of pelitic origin, interbeded with 1-3 beds of green-schists., The whole thickness varies from 500 to 1500m., according to the change in thickness of the intercalated green-schists beds., 2) The middle sub-group is divided into the lower Koboke Formation and the upper Minawa Formation., In the region south of the Simomyo-Tuneyama fault, the Nisiiya Group is overlain by the Koboke Formation., The relation between the two rock series is a distinct clilno-unconformity, called Minamihiura Unconformity., Koboke Formation: The component members are mainly sandston-schists, interbedded with beds of black-schists and green-schists., The whole thickness varies from 200 to 400m., Minawa Formation: The formation comprises two or more beds of green-schists 100-400m., in thickness., The other members are greenish or pinkish quartz-schists (sometimes attaining to 100m., in thickness) and black-schists., The whole thickness of the formation exceeds 800m., 3) The upper sub-group is characterized by the presence of white siliceous rocks, which also characterize the non-metamorphic Palaeozoic formation in the Titibu-Zone., The other members are black-schists, green-schists, sandstone-schists, calcareous schists, and semi-schists corresponding to them., The lower and the middle sub-groups of the Yoshinogawa Group correspond respectively to the Oboke and the Bessi Series by T., Ogawa (1902)., The geological structure of the region is characterized by domes or dome-like anticlines and basins or basin-like synclines in the non-spotted schists zones and by folds of recumbent types in the spotted schists zones.,View full abstractDownload PDF (1981K) -
Eitaro TAKAHASHI1951 Volume 57 Issue 668 Pages 191-193
Published: May 31, 1951
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSDownload PDF (437K)
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