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Volume 73, Issue 1
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KEN SHIBATA, MASAHIRO ITO1978 Volume 73 Issue 1 Pages 1-4
Published: January 05, 1978
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSMuscovite separated from schist in the Asahidake-Shiroumadake area, northern Hida mountains, is dated as 311±10 m. y. and 323±20 m. y. by K-Ar and Rb-Sr methods, respectively. The ages are similar to those for the Omi schist, and confirm the mid-Paleozoic metamorphism in the Hida marginal belt. A low initial 87Sr/86Sr ratio for the schist indicates that the rock originated in Paleozoic time.View full abstractDownload PDF (261K) -
Yukio Hujimoto1978 Volume 73 Issue 1 Pages 5-17
Published: January 05, 1978
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe Shirakamidake composite granitic pluton is one of the granitic basement complexes in the Green Tuff region in Northeastern Japan. It consists largely of three granitic submasses, AE, B, and AW. In addition, halleflinta or prophyroid facies (submass C) is distributed between B and AW. Lithologically, AE and AW are composed of adamellite or granite which is free from hornblende and rich in potassium feldspar. It intrudes into the AE submass. The sequential relation of B to AE may be considered as being reflected by the triclinicity of potassium feldspar.
Structurally, the submass AE is a half-dome or south-dipping wavy form, while both submasses B and C are east-dipping homoclinic forms. The foliation of B is strong in the eest and becomes weak twoards the eastern contact. The northern part of AW forms an east-dipping homocline, but the southern part forms a northerly pitching synclinal structure where schistosity becomes steeper twoards the east.
Genetically, there are two kinds of schistosity in this pluton. The primary schistosity is shown by the orientation of plagioclase, hornblende, biotite and potassium feldsapr in the magmatic flow stage. The secondary schistosity is shown by the mylonite which is partly protoclastic and partly cataclastic.
Judging from the field observation and structural analysis on schistosity and lineation, it is concluded that submass AW was subjected to intense deformation in the later stage of magmatic consolidation and formed a synclinal structure this deformation may be originally due to the uplift of the eastern area which includes submass AE.View full abstractDownload PDF (1790K) -
Kiyoshi Ishibashi, Michitoshi Miyahisa, Motoi Sasaki1978 Volume 73 Issue 1 Pages 18-25
Published: January 05, 1978
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSClinohumite is found in serpentinite near Fujiwara village, Ehime Prefecture, which belongs to the central part of the Sambagawa metamorphic terrane. The mineral forms as vein or lenticular aggregate in serpentinite and shows reddish brown to dark brown in color.
Under microscope, it shows strong pleochroism and dispersion, some crystals have lamella twins parallel to 001. The refractive indices are α=1.637, β=1.645-1.648, γ=1.669 and γ-α=0.032.
Chemical composition and X-ray powder data of the clinohumite are presented and genetic relation of coexisting minerals are discussed in this paper.View full abstractDownload PDF (390K) -
Satoshi Kanisawa1978 Volume 73 Issue 1 Pages 26-29
Published: January 05, 1978
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSFluorine determination in silicate rocks has been done without separation of aluminum using a specific ion electrode. Analyses were made using sodium carbonate fusion with zinc oxide and 0.2M sodium citrate-0.2M potassium nitrate solution as a buffer.
The results of investigation on the aluminum interference show that the influence is very small, and those of determination of standard rocks show good agreement with the reported values. This method is very useful for determination of fluorine in silicate rocks.View full abstractDownload PDF (144K)
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