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Article type: Photogravure
1986 Volume 31 Issue 2 Pages
App6-
Published: July 01, 1986
Released on J-STAGE: January 15, 2018
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Hiromi SUGIYAMA, Masao HAYASHI, Toshio FUJINO
Article type: Article
1986 Volume 31 Issue 2 Pages
85-94
Published: July 01, 1986
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Fission track ages of zircon from the Unzen volcanic rocks in western Kyushu have been dated using the external surface re-etch method. The ages, including standard errors, of the basal volca-niclastic rocks, the Tatsuishi formation, are 0.28±0.05 Ma and 0.25±0.05 Ma. The next oldest Takadake lavas range form 0.26 to 0.20 Ma: the Yatake lava 0.26±0.04 Ma, the Takaiwayama lava 0.24±0.06 Ma, the Kinugasayama lava 0.23±0.08 Ma, and the Takadake lava 0.20±0.05 Ma. The following Kusenbudake lavas fall in a narrow range form 0.19 to 0.17 Ma: the Sarubayama lava 0.19 ± 0.03 Ma, the Azumadake lava 0.18±0.06 Ma, and the Kusenbudake lava 0.17±0.06 Ma. The most recent Fugendake lavas are younger than 0.07 Ma: the Mayuyama lava 0.07±0.02 Ma, the Fugendake lava 0.07±0.02 Ma, and the Myokendake lava 0.06±0.03 Ma. These lavas are probably too young to be accurately dated using the fission track method. It is inferred from the age determination and geological evidence that the volcanic activity of Unzen volcano began about 0.30 Ma ago and has continued into Recent time, with a period of dormancy between 0.17 and 0.07 Ma, during which the Unzen Graben acquired its present form.
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Setsuya NAKADA
Article type: Article
1986 Volume 31 Issue 2 Pages
95-110
Published: July 01, 1986
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Eruptions of lava domes and thick lava-flows of hornblende andesites characterize the Daisen volcanic belt in Kyushu, whereas eruptions of voluminous pyroclastics and thin lava-flows of pyroxene andesites do the Kirishima volcanic belt. The hornblende andesites contain more abundant phenocrysts and have higher Fe
3+/Fe
2+ ratios than the pyroxene andesites. Sixty-two samples of rocks from the two volcanic belts were analyzed with X-ray fluorescence spectrometer. The hornblende andesites are lower in Fe/Mg, K/Ba and Rb/K ratios, poorer in Zr, Y, Rb and Cu contents, and richer in Nb, Sr and Ba contents than the pyroxene andesites. Along the Daisen volcanic belt, K/Rb and Ba/K ratios, and Sr and Ba contents in rocks increase eastwards. On the other hand, Fe/Mg ratio and Ti, K, P, Nb, Zr, Y, Sr, Rb, Ga and Ba contents in rocks increase northwards along the Kirishima volcanic belt. Although fractionation of hornblende and magnetite from hornblende andesite magma gives a possible explanation to the difference in major-oxide, Y and V compositions, the difference in other trace-element compositions between the hornblende and the pyroxene andesites may reflect differences in source materials. Chemical variations along the Kirishima volcanic belt may have originated either from northward increase in the degree of fractionation at higher pressures or from northward decrease in the degree of partial melting of source materials.
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Keiko SUZUKI-KAMATA, Tadahide UI, Keiichi SAKAGUCHI
Article type: Letter
1986 Volume 31 Issue 2 Pages
111-112
Published: July 01, 1986
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Tadahide UI, Hiromu OKADA, Kenji NOTSU
Article type: Scientific Communication
1986 Volume 31 Issue 2 Pages
113-116
Published: July 01, 1986
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K. Kaminuma, M. Baba, J. Amino
Article type: Abstract
1986 Volume 31 Issue 2 Pages
117-
Published: July 01, 1986
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H. Shimizu, N. Matsuwo
Article type: Abstract
1986 Volume 31 Issue 2 Pages
117-
Published: July 01, 1986
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A. Kubotera, T. Mitsunami, S. Omote, Y. Kinoshita
Article type: Abstract
1986 Volume 31 Issue 2 Pages
117-118
Published: July 01, 1986
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Y. Ida, M. Yamaguchi, F. Masutani
Article type: Abstract
1986 Volume 31 Issue 2 Pages
118-
Published: July 01, 1986
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M. Iguchi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
118-119
Published: July 01, 1986
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T. Watanabe
Article type: Abstract
1986 Volume 31 Issue 2 Pages
119-
Published: July 01, 1986
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Y. Motoya
Article type: Abstract
1986 Volume 31 Issue 2 Pages
119-120
Published: July 01, 1986
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S. Watanabe, N. Kano, K. Yamaguchi, T. Yokokura
Article type: Abstract
1986 Volume 31 Issue 2 Pages
120-
Published: July 01, 1986
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M. Kato, I. Ohno, E. Ohtani, K. Takaichi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
120-121
Published: July 01, 1986
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A. Yamamoto, Y. Fukao, M. Kono
Article type: Abstract
1986 Volume 31 Issue 2 Pages
121-
Published: July 01, 1986
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M. Kono, Y. Fukao, A. Yamamoto
Article type: Abstract
1986 Volume 31 Issue 2 Pages
121-
Published: July 01, 1986
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Y. Morita, H. Hamaguchi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
121-122
Published: July 01, 1986
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T. Seno, M. Takahashi, Y. Tatsumi, Y. Kobayashi, K. Ishisaka
Article type: Abstract
1986 Volume 31 Issue 2 Pages
122-123
Published: July 01, 1986
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T. Tada, Y. Kobayashi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
123-
Published: July 01, 1986
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K. Nishimura
Article type: Abstract
1986 Volume 31 Issue 2 Pages
123-124
Published: July 01, 1986
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H. Sato, M. Yamano, S. Uyeda, E. Tokuyama, T. Matsuda, M. Kimura, S. K ...
Article type: Abstract
1986 Volume 31 Issue 2 Pages
124-
Published: July 01, 1986
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T. Ishii, S. Ohta
Article type: Abstract
1986 Volume 31 Issue 2 Pages
124-125
Published: July 01, 1986
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E. Takahashi, J.-G. Schilling
Article type: Abstract
1986 Volume 31 Issue 2 Pages
125-
Published: July 01, 1986
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E. Takahashi, K. Uto, T. Yoshida
Article type: Abstract
1986 Volume 31 Issue 2 Pages
125-126
Published: July 01, 1986
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Y. Tatsumi, A. Sudo, N. Nakamura
Article type: Abstract
1986 Volume 31 Issue 2 Pages
126-
Published: July 01, 1986
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N. Fujii, K. Osamura
Article type: Abstract
1986 Volume 31 Issue 2 Pages
126-127
Published: July 01, 1986
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Y. Ida
Article type: Abstract
1986 Volume 31 Issue 2 Pages
127-
Published: July 01, 1986
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T. Kagiyama
Article type: Abstract
1986 Volume 31 Issue 2 Pages
127-128
Published: July 01, 1986
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M. Sugihara, T. Ishido
Article type: Abstract
1986 Volume 31 Issue 2 Pages
128-
Published: July 01, 1986
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T. Ishido, T. Kikuchi, M. Sugihara
Article type: Abstract
1986 Volume 31 Issue 2 Pages
128-
Published: July 01, 1986
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T. Yamazaki, A. Usui
Article type: Abstract
1986 Volume 31 Issue 2 Pages
128-129
Published: July 01, 1986
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I. Yokoyama
Article type: Abstract
1986 Volume 31 Issue 2 Pages
129-
Published: July 01, 1986
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N. Fujii, T. Nakano
Article type: Abstract
1986 Volume 31 Issue 2 Pages
129-
Published: July 01, 1986
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H. Kamata
Article type: Abstract
1986 Volume 31 Issue 2 Pages
130-
Published: July 01, 1986
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T. Koyaguchi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
130-
Published: July 01, 1986
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K. Suzuki-Kamata
Article type: Abstract
1986 Volume 31 Issue 2 Pages
130-131
Published: July 01, 1986
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Y. Hayakawa
Article type: Abstract
1986 Volume 31 Issue 2 Pages
131-
Published: July 01, 1986
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N. Sakamoto, M. Obata
Article type: Abstract
1986 Volume 31 Issue 2 Pages
131-132
Published: July 01, 1986
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K. Yamashina
Article type: Abstract
1986 Volume 31 Issue 2 Pages
132-
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M. Takahashi
Article type: Abstract
1986 Volume 31 Issue 2 Pages
132-133
Published: July 01, 1986
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S. Nakada, M. Senoh
Article type: Abstract
1986 Volume 31 Issue 2 Pages
133-
Published: July 01, 1986
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I. Kaneoka
Article type: Abstract
1986 Volume 31 Issue 2 Pages
133-
Published: July 01, 1986
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M. Tsuchide, I. Sakurai, H. Sato, J. Ossaka
Article type: Abstract
1986 Volume 31 Issue 2 Pages
133-134
Published: July 01, 1986
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J. Ossaka, C. Mitsuno, T. Shibata, T. Matsuda, J. Hirabayashi, M. Tsuc ...
Article type: Abstract
1986 Volume 31 Issue 2 Pages
134-135
Published: July 01, 1986
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T. Kumagai, S. Kishi, H. Ohkura
Article type: Abstract
1986 Volume 31 Issue 2 Pages
135-
Published: July 01, 1986
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Y. Katsui, S. Kawachi, C. Hector, M. Lucia Calvache
Article type: Abstract
1986 Volume 31 Issue 2 Pages
135-136
Published: July 01, 1986
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Y. Tanaka
Article type: Abstract
1986 Volume 31 Issue 2 Pages
136-
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H. Watanabe
Article type: Abstract
1986 Volume 31 Issue 2 Pages
136-137
Published: July 01, 1986
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H. Y. Mori
Article type: Abstract
1986 Volume 31 Issue 2 Pages
137-
Published: July 01, 1986
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H. Hirai, S. Arai
Article type: Abstract
1986 Volume 31 Issue 2 Pages
137-138
Published: July 01, 1986
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