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Volume 40 (1986)
- Issue 6 Pages 373-
- Issue 5 Pages 307-
- Issue 4 Pages 227-
- Issue 3 Pages 147-
- Issue 2 Pages 89-
- Issue 1 Pages 1-
Volume 40, Issue 3
Displaying 1-7 of 7 articles from this issue
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Masahiro SHIBA, SURUGA BAY COLLABORATIVE RESEARCH GROUPArticle type: Article
1986 Volume 40 Issue 3 Pages 147-165
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSThe Neogene in the Fuji River Valley has been considered to be disrupted by several major thrusts to form a westward-dipping imbricated structure (MATSUDA, 1961). The Neogene correlation of the southern and northern Fuji River Valley is a troublesome problem by reason of remarkable lateral facies changes. In the present paper, the authors present the revised stratigraphy and a description of the geological structure of the Neogene in the northern Shimizu City, which occupies the southwestern corner of southern Fuji River Valley. The Hamaishidake Group developed in and around the studied area is subdivided into six formations, namly the Kogochi, Murono, Sattatoge, Utsugino, Nakagochi and Kawaino Formations in ascending order. The Utsugino, Nakagochi and Kawaino Formations are distributed in the studied area. The Utsugino Formation is distributed on the both wings of the Inasegawa Anticline. On the east wing volcanic conglomerate is characteristic of the Formation (The Yamauchi and Sakurano Members), whereas on the west wing dominate mudstone-rich alternation of sandstone and mubstone (the Hirayama Member). The Nakagochi Formation is subdivided into five members: the Nakaisshiki, Kanzawara, Mobata, Wadashima and Tozurasawa Members in ascending order. The Nakaisshiki is composed mainly of pyroclastic rock and conglomerate, the Kanzawara of conglomerate and sandstone-rich alternation of sandstone and mudstone, the Mobata of sandstone-rich alternation of sandstone and mudstone with conglomerate, the Wadashima of sandstone-rich alternation of sandstone and mudstone, the Tozurasawa of pyroclastic rock and mudstone. The Kawaino Formation mainly consists of conglomerate. The Hamaishidake Group was subjected to a series of NS-trending folding movement which occurred during the Hamaishidake stage (Pliocene). The NS-, NE-SW- and EW-trending faults are remarkable in this area, among which the NE-SW- and EW-trending faults were formed during the post-Hamaishidake pre-Sasanotoge stage (Pleistocene). On the basis of planktonic foraminifer and molluscan faunas, the geological age of the Hamaishidake Group is assigned to the Pliocene. As a result of this stratigraphic and structural study, the once estimated "Nakagochi Thrust" is proved to be only a fake.View full abstractDownload PDF (2824K) -
Takahito NAKA, Hiromichi WATASE, Takao TOKUOKAArticle type: Article
1986 Volume 40 Issue 3 Pages 166-176
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSThe middle to upper Permian Nishiki Group distributed in the Muikaichi-cho area is divided lithologically into Na (chert facies), Nb (mudstone facies), Nc (sandstone facies) formations in ascending order. Na formation, 120m in maximum thickness is composed of massive and bedded cherts which are intercalated with thin reddish mudstone layers and lenticular bodies of fine sandstone. Nb formation, 200m in maximum thickness, is mainly composed of black mudstone which is frequently intercalated with acidic tuffs. Nc formation is 500-1000m in thickness, and consists mostly of massive sandstone. The newly obtained Permian radiolarians have ascertained the hitherto undetermined age of the Nishiki group. Na formation includes upper part of Albaillella sinuata Range-zone to Pseudoalbaillella sp. C Assemblage-zone, and Nb formation includes Ps. sp. C A-zone to lower part of Follicucullus scholasticus A-zone. Nc formation also includes lower part of Fo. scholasticus A-zone. Then Nishiki Group of the area is safely correlated to Leonardian to Guadalupian (middle to late Permian) in age. The Permian radiolarian biostratigraphy has been established in the Tamba Belt, where the strata from upper part of A. sinuata R-zone to lower part of Fo. scholasticus A-zone are represented by bedded cherts of only 13 meters thick, while the same ones of the present area are expressed by clastic rocks of mudstone and sandstone of more than 500 meters thick, although the lowest part of which includes cherty rocks. The frequently intercalated acidic tuffs of the middle Permian, especially of Fo. monacanthus A-zone, indicates the existence of active and probably extensive acid volcanisms on the neighbouring hinterland.View full abstractDownload PDF (1473K) -
an example of the Oguni Region, Niigata Sedimentary Basin, Central JapanMikako SAWAGURI, Katsuki KUROKAWAArticle type: Article
1986 Volume 40 Issue 3 Pages 177-191
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSTransition of volcanism from Pliocene to early Pleistocene was revealed by means of subaqueous tephra layers intercalated in the marine, brakish and fluvial formations in the Oguni region, Niigata sedimentary basin. These formations, namely the Hachikokusan, Suganuma and Hachioji Formations and the Uonuma Group in ascending order, pile up conformably and attain 2000m in total thickness. Rhyolitic to andesitic tephras of more than 200 layers are intercalated in these formations. To visualize the transition of volcanism, the authors divided these formations into 10 Tephrozones (TNO-I〜TNO-X) in respect to the distinctive features of tephras, that is (1) frequency of appearence of tephra layers, (2) petrography and rock types and (3) their mode of occurrence and lithofacies. In latest Miocene to earliest Pliocene (TNO-I), only two rhyolitic thin layers are intercalated among nonvolcanogenic sediments of 280m thick. In early Pliocene, andesitic tephras with lava flows are dominant in the lower part (TNO-II), but only rhyolitic tephras are interbedded in the upper part (TNO-III). Middle Pliocene can be characterized by the scanty of tephra layers, which are not found in the lower part (TNO-IV) and a few rhyolitic thin layers can be found in the upper part (TNO-V). In late Pliocene (2.9-2.1 m. y.), with the deposition of the Uonuma Group, pumiceous deposits of more than 10m thick are occasionally intercalated (TNO-VI). Rhyolitic volcanism gets to be intensive from latest Pliocene to earliest Pleistocene (2.1-1.7 m. y.) (TNO-VII), in which rhyolitic tephras occupy more than 50% of total thickness in some parts. In early Pleistocene, rhyolitic and hornblende dacitic ones are occasionally interbedded in the lower part (1.7-1.3 m. y.) (TNO-VIII), but tephras are rarely intercalated in the ascending formations (1.3-0.9m. y.) (TNO-IX). In TNO-X (0.9-0.7m. y.), airfall tephras by eruptions at remote regions can only be intercalated. It is characteristic, however, that pink-colored dacitic ones are not uncommon in TNO-X, which is indicative of the transition of volcanism in the source areas. Transition of volcanism as revealed in the Oguni region is almost commonly noticed through the Niigata sedimentary basin, while in the southern uplifting area adjacent to the basin, andesitic volcanism was successively in active since late Pliocene.View full abstractDownload PDF (2872K) -
Ryuji AOYAGIArticle type: Article
1986 Volume 40 Issue 3 Pages 192-204
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSTo establish a method for the identification of tephras by chemical means, some minor components (V2O3, MnO, ZnO) in ferromagnetic minerals were determined together with their major components (FeO, Fe2O3, TiO2). The effects of the contamination of micro-components from the ferromagnesian silicate minerals co-existing with ferromagnetic mineral specimens were carefully examined. The MnO contents of pyroxenes or hornblendes are slightly higher than that of ferromagnetic minerals, th influence, however, can be neglected if the purity of the sample (presented as FeO+Fe2O3+TiO2%) is higher than 93%. More than 200 samples of 100 layers of marker-tephras taken from South-Kanto, North-Kanto, Shinshu and Aomori Loams were studied. Among the ratios of the chemical components in the ferromagnetic minerals, Mn/Fe, V/Ti, V/Mn, and Zn/V values widely and thus seem to be effective for the identification of these tephras. Closer examination of the chemical data indicates that the following combination of elements is very useful for identification of almost all tephras; the tephras are first classified in terms of TiO2 content of ferromagnetice minerals, then subdivided on the basis of the Mn/Fe vs. V/Ti (or V/Mn vs. Zn/V) correlation diagrams for each TiO2-group.View full abstractDownload PDF (1129K) -
Masayuki SAKAKIBARA, Keisaku TANAKAArticle type: Article
1986 Volume 40 Issue 3 Pages 205-206a
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSDownload PDF (611K) -
Toshiro SAKAEArticle type: Article
1986 Volume 40 Issue 3 Pages 207-220
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSDownload PDF (1479K) -
14C age of Quaternary deposits in Japan (158)Tetsuyoshi YAMAZAKIArticle type: Article
1986 Volume 40 Issue 3 Pages 221-223
Published: May 25, 1986
Released on J-STAGE: July 27, 2017
JOURNAL OPEN ACCESSDownload PDF (299K)
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