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Volume 50 (1996)
- Issue 6 Pages 427-
- Issue 5 Pages 341-
- Issue 4 Pages 273-
- Issue 3 Pages 203-
- Issue 2 Pages 95-
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Volume 50, Issue 5
Displaying 1-10 of 10 articles from this issue
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Toyoki Aoki, Katsuki KurokawaArticle type: Article
1996 Volume 50 Issue 5 Pages 341-361
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSTephrostratigraphy of Pliocene to early Pleistocene Kawazume, Nadachi, Tanihama and Torigakubi Formations in the Nisikubiki area, western Joestu City in northern Fossa Magna, was establised. Thirty-two ash markers were described in terms of their horizon, lithofacies, sedimentary unit association, petrographic characteristics of components, heavy mineral association, and shape and chemical composition of glass shards. Among these in the Nishikubiki area, the following ashes were regionally correlated over more than 100km in the Niigata sedimentary basin such as the Tomikura anticlinal area (east of Arai City), Higashikubiki and Uonuma Hills, and Hachikoku-Chuo-Nishiyama Oil Fields. The Msp ash in the lowermost part of Kawazume Formation can be correlated to the Ykp ash in the lower part of Hamatsuda Formation, and also T1 ash in the lowermost Sarumaru Formation of western Nagano City. The Oop ash in the lowermost part of Tanihama Formation to the Hap-2 ash in the uppermost part of Hachikokusan Formation, and the Arm ash in the middle part of Tanihama Formation to the Hog-a ash in the middle part of Hachioji Formation in the Hachikoku Oil Field. On the basis of lateral changes of thickness and facies, the most of regional Pliocene ash layers in Niigata sedimentary basin were transported from northern Nagano prefecture to northeastward of Higashikubiki and Hachikoku-Chuo-Nishiyama Oil Fields in Pliocene, and the Nishikubiki area were referred to distributary area to the main passage area.View full abstractDownload PDF (3160K) -
Akihiko Suzuki, Masayuki MukaiArticle type: Article
1996 Volume 50 Issue 5 Pages 362-369
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSMolluscan fossils are abundantly discovered from the Miocene Biei Formation which is previously named as the so-called Neogene Tertiary, in the Biei area, central Hokkaido. The molluscan assemblages of the formation are composed of 16 bivalves and 6 gastropods, and is assigned to the Takinoue molluscan fauna based on the occurrence of Crassostrea gravitesta, Cultellus izumoensis, Mizuhopecten kobiyamai and Cerithideopsilla cf. minoensis. Fossil assemblage similar to those of the Biei Formation is also recognized in the Miocene Yakeyama Formation in the Sunagawa area. From the viewpoint of molluscan biostratigraphy, these fossil-bearing strata are correlative to the Takinoue stage of the early Middle Miocene that is corresponded to the Mid-Neogene climatic optimum. From the paleozoogeographic view, the Takinoue molluscan fauna is considered to the warm-temperate realm as lacking for typical associations of the Arcid-Potamid fauna (subtropical elements) and rare occurrence of cold-water species. Hokkaido is considered to have been occupied a peculiar paleozoogeographic position during the early Middle Miocene as a marginal sea of the warm-water realm, because coexistence of three different types of molluscan fauna such as the Kadonosawa (subtropical), Takinoue (warm-temperate) and Chikubetsu (cool-temperate) faunas are recognized in the area.View full abstractDownload PDF (1845K) -
Ryotaro Nomura, Katsuhiko Furuyama, Atsuo Kotaki, Yoichi Inoue, Akira ...Article type: Article
1996 Volume 50 Issue 5 Pages 370-384
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSKamisano volcano is a Quaternary basaltic monogenetic volcano dated at about 0.23 Ma by K-Ar, located in the eastern part of the San'in district. It consists of lava flows and pyroclastic fall deposits. Two volcanic vents (vents A and B) and the surrounding volcanic body were exposed during the construction of Tajima Airport. The eruption history of the Kamisano volcano is divided into four stages (stages I-IV), each of which consists of an earlier phreatomagmatic eruption of ash and/or lapilli, and a subsequent Strombolian eruption. One lava flow effused northeastward and ran down along a valley. Clastogenic lave, produced by the rapid accumulation of hot bombs erupted from vent A, flowed several tens of meter southward. These lavas (Kamisano lava) hava a basaltic andesite composition with SiO_2=51. 8-53.6 wt.%. The chemical variations among the lavas result from both contamination by the basement rhyolite and crystallization differentiation. The estimated chemical composition of the Kamisano lava prior to the contamination and the differentiation is lower in K_2O than the Quaternary basaltic lavas from other volcanoes, e.g. Kannabe monogenetic volcanoes, surrounding the Kamisano volcano.View full abstractDownload PDF (2806K) -
Shuichiro Yokota, Tadayoshi NakatsuArticle type: Article
1996 Volume 50 Issue 5 Pages 385-390
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSMany surface ruptures were recognized in southeastern hilly land of the Rokko Mountains at the 1995 Hyogoken-nanbu Earthquake. One of them elongates more than 250m with remarkable displacements on the ground. Results of trench investigation show that down sliding of embankment along old valley slope brought about surface ruptures such as "surface faulting". Although surface displacements have typical strike-slip sense in some segments, they can be understood by the oblique relation between general trend of the rupture and slip vector along the individual old valley slopes.View full abstractDownload PDF (715K) -
Takeshi Kamei, Masao EnomotoArticle type: Article
1996 Volume 50 Issue 5 Pages 391-402
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSThis paper describes the effects on the coefficient of permeability of soils due to both rainfall and groundwater inflow, and the consequences of changes in these parameters on slope stability and the behaviour of pore water pressure and seepage in the slope. Finite element analysis using saturated-unsaturated seepage was performed on model slopes, with differing coefficients of permeability. The analytical conditions used in the present study also considered the presence of tension cracks and/or slip surfaces with all combinations of rainfall, and groundwater inflow from upslope. The combined effects of varying permeability, rainfall and slip surface conditions on the behaviour of pore water pressure and groundwater seepage in the slope are discussed quantitatively by a detailed examination of soils of differing permeability, and variation of the vector due to rainfall and pore water pressure at the slip surface with elapsed time. Furthermore, we investigated slope stability using the analytical results of the seepage flow. Numerical illustration confirms the usefulness of the present analysis which can be considered suitable for preliminary work, due to the use of idealized assumptions. Direct application of these results to natural slopes requires caution. This study provides, however, a basis for extending slope stability analysis to quantitative evaluation, once seepage flow behaviour of natural slopes is understood.View full abstractDownload PDF (1503K) -
Pirika limestone cave, Imakane, southwestern HokkaidoHajime Kusaka, Naruhiko Kashima, Naofumi Itoda, Ayumu Nojo, Pirika Sir ...Article type: Article
1996 Volume 50 Issue 5 Pages 403-407
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSDownload PDF (1484K) -
Tatsuya Sakumoto, Koji Seto, Katsumi TakayasuArticle type: Article
1996 Volume 50 Issue 5 Pages 408-413
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSDownload PDF (1077K) -
Toshio KusunokiArticle type: Article
1996 Volume 50 Issue 5 Pages 414-418
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSDownload PDF (692K) -
Tsuneo Nakajima, Junzo Uchiyama, Isao IbaArticle type: Article
1996 Volume 50 Issue 5 Pages 419-421
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSDownload PDF (539K) -
Keiji TakeuchiArticle type: Article
1996 Volume 50 Issue 5 Pages 422-423
Published: September 25, 1996
Released on J-STAGE: June 06, 2017
JOURNAL OPEN ACCESSDownload PDF (334K)
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