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Volume 53 (1999)
- Issue 6 Pages 405-
- Issue 5 Pages 325-
- Issue 4 Pages 247-
- Issue 3 Pages 171-
- Issue 2 Pages 91-
- Issue 1 Pages 1-
Volume 53, Issue 4
Displaying 1-8 of 8 articles from this issue
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Atsushi UrabeArticle type: Article
1999 Volume 53 Issue 4 Pages 247-257
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSThe Plio-Pleistocene Osaka Group in Osaka, the Plio-Pleistocene Kakegawa Group in Shizuoka, the Plio-Pleistocene Uonuma Group in Niigata, the Plio-Pleistocene Kazusa Group and the Pleistocene Toyofusa Group in the Boso Peninsula are typical forearc and backarc basin-fill successions in Japan. The third-order and the fourth- or fifth-order depositional sequences are recognized within these successions. All these sequences are believed to have been formed by glacio-eustatic sea-level changes, and can be compared with the sea-level curve by the correlation of pyroclastic layers (tephra beds) in these basins. Based on this comparison, it is concluded that the fourth- or fifth-order depositional sequences in the different sedimentary basins were formed in response to the fourth- or fifth-order glacio-eustatic sea-level changes. Especially, the fourth- or fifth-order depositional sequences in the transgressive stage of the third-order sea-level changes are well recognized within each succession in the different areas. In contrast, the third-order depositional sequences (transgression-regression cycle) of these groups differ and do not correspond to the third-order sea-level change. The reexamination of formative process of the third-order depositional sequences are necessary to estimate the amount of sea-level changes and tectonic movement of each basin.View full abstractDownload PDF (1750K) -
Hiroyuki TarunoArticle type: Article
1999 Volume 53 Issue 4 Pages 258-264
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSThe stratigraphic position of proboscidean fosssils from the Middle to Lower Pleistocene and Pliocene formations of Japanese Islands were reexamined based on the tephrochronology. Stegodon shinshuensis appeared at the earliest Pliocene and extincted in the lower part of Gauss Chron. But, the stratigraphic range of Stegodon shinshuensis seems to be variable in basin by basin. This discordance may be due to insufficient tephrochronological correlation and poor occurrence of the fossil. The stratigraphic range of Stegodon aurorae is represented within the lowermost and lower part of the Osaka Group, namely from the just under the Mitsumatsu Tuff layer to the Yellow Tuff layer, except only one specimen from the Kobiwako Group. The stratigraphic range of Mammuthus protomammonteus is assigned to the lower and upper part of the Osaka Group, namely from the Yellow Tuff layer to the Ma5 bed. Although, specimens of M. protomammonteus are yielded from the horizon upper than that in the Osaka Group in the Kazusa Group. those specimens might be derived fossils. The stratigraphic range of Stegodon orientalis is represented by the upper part the Osaka Group, namely from the just under the Ma6 bed to the Ma7 bed.View full abstractDownload PDF (1229K) -
Tokiyuki Sato, Koji Kameo, Isao MitaArticle type: Article
1999 Volume 53 Issue 4 Pages 265-274
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSWe describe in detail the validity of the latest Cenozoic calcareous nannofossil datums recognized in the North Atlantic Ocean during DSDP Leg 94 based on the relationship among the nannofossil datums, magnetostratigraphy and oxygen isotope stages. The relations found in the uppermost sequence of Hole 607A located in the North Atlantic Ocean, are same as those in the Boso Peninsula and Choshi area located in the Pacific side of Japan. This indicates that the Quaternary nannofossil datums are useful for detailed age determination such as hundred kilo-years order. On the basis of nannofossil datum planes, we correlate the Quaternary sequences in both Japan Sea and Pacific sides, and also clarify the relationship among nannofossil datums, tephrostratigraphy and the oxygen isotope stages. We also discuss some problems on the correlation among the Pliocene sequences around Japan based on nannofossils. The nannofossil assemblages of the Pliocene sequences in Japan Sea side are composed of low species diversity with abundant occurences of cold water nannofossils, and are correlative to those in the Arctic Ocean. On the contrary, the assemblages in the Pacific side, are characterized by high species diversity including a lot of warm water nannofossils, and are same as those found in low-latitude regions. This indicates that two different paleobiogeograhical provinces were present around Japan.View full abstractDownload PDF (1471K) -
Yasufumi Satoguchi, Yoshitaka Nagahashi, Katsuki Kurokawa, Shusaku Yos ...Article type: Article
1999 Volume 53 Issue 4 Pages 275-290
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSMany tephra beds are intercalated in the Pliocene to Pleistocene formations in Japan. Some of them can be correlated over distant areas. The Pliocene to Lower Pleistocene formations at Saijo, Tsunozu, Shobudani, Osaka, Lake Biwa, Ise Bay, Kakegawa, Himi, Sarumaru, Nishikubiki, Niigata and Boso Peninsula areas are summerized and correlated each other based on tephrostratigraphy, biostratigraphy, magnetostratigraphy and radiometric dating. A newly correlation chart of these formations is established. This chart, however, contains some problems in estimated age of the tephra beds in the Pliocene formations. The age of T1-Ykp, Ohta-PM-Znp, Souri-YT3-Tn Nym volcanic ash beds has been estimated differently from one area to the others.View full abstractDownload PDF (2397K) -
Todo Collaborative Research GroupArticle type: Article
1999 Volume 53 Issue 4 Pages 291-306
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSThe Tokai Group occupies the eastern part of the distribution of the Middle Miocene to Middle Pleistocene Second Setouchi Supergroup. The group around Tajimi City is composed of fluvial sediments, and indicates Middle Miocene to Late Pliocene in age. The group around Tajimi City is divided into the Tokiguchi Porcelain Clay Formation and Toki Sand and Gravel Formation with conformable relationship. The former is dominant of sand and mud, and ranges generally between 10 and 30m thickness, while the latter comprises mainly gravel, and its thickness is more than 40m. Lithologically, the Toki Sand and Gravel Formation is composed of two types of gravels; one dominates in chert clasts, and the other dominates in acid volcanic rocks derived from the Nohi Rhyolites. Chert clasts dominate type distributed in the central to northern parts of the study area, and volcanic rock dominate type covers the central to southern parts, approximately. The sedimentary basin around Tajimi City is fault-bounded, and is made up of small basement blocks less than 20 km^2 in area. The formation of small blocks is ascribed to the brittleness around the terrane boundary between the Ryoke and Mino Belts. The characteristics of fault-bounded basin around Tajimi City are common to other basins of the Second Setouchi Supergroup. The basin around Tajimi City, however, never suggests the acceleration of subsiding from 2.5Ma, which is common to other basins of the supergroup, and indicates very low rate of sedimentation.View full abstractDownload PDF (3769K) -
Kiichi ObataArticle type: Article
1999 Volume 53 Issue 4 Pages 307-313
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSAbundant specimens of trace fossils have been found from several exposures of the Jurrasic and the Cretaceous sediments in the northeastern area of the Kanto Mountains. They belong to Phycosiphon incertum and Scalarituba isp. Size distributions of these ichnospecies are different in each locality and horizon. These trace fossils are found in silty part of the alternating sandstone and mudstone beds or in the single mudstone layer. Judging from the sedimentary feature and the mode of the fossil occurrence, these trace fossils are considered to be pascichnia formed in turbidite. They are presumed to reflect frequent sedimentation, because they belong to a simple palaeoich-nocoenosis composed of only two ichnospecies formed by opportunisitic burrowers.View full abstractDownload PDF (1960K) -
Shu'an JiArticle type: Article
1999 Volume 53 Issue 4 Pages 314-316
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSDownload PDF (570K) -
Mitsuru NakagawaArticle type: Article
1999 Volume 53 Issue 4 Pages 317-318
Published: July 25, 1999
Released on J-STAGE: July 14, 2017
JOURNAL OPEN ACCESSDownload PDF (281K)
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