• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

2002 Fiscal Year Final Research Report Summary

Geologic study of oceanic plate components in the northern Chichibu belt

Research Project

Project/Area Number 12640448
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Geology
Research InstitutionThe Independent Administrative Institution National Science Museum (2001-2002)
National Museum of Nature and Science,Tokyo (2000)

Principal Investigator

SAITO Yasuji  Department of Geology and Paleontology Director, 地学研究部, 部長 (00000133)

Co-Investigator(Kenkyū-buntansha) YOKOYAMA Kazumi  Department of Geology and Paleontology Chief, 地学研究部, 室長 (40126628)
Project Period (FY) 2000 – 2002
KeywordsChichibu belt / accretion complex / radiolaria / Jurassic / monazite / U-Th-Pb age
Research Abstract

The northern part of the Chichibu belt in the Kanto Mountains consists mainly of Jurassic terrigeneous clastic rocks and various-sized exotic blocks of oceanic plate origin, such as Triassic bedded chert, late Paleozoic limestone and greenstone. Mode of occurrence and cc-existence of the blocks with different geologic ages indicate that the Chichibu belt was formed as an accretion complex in relation to oceanic plate subduction. It is considered that the subduction have occurred along the East Asia continental margin. This is supported by the U-Th-Pb ages of detrital monazite grains of the complex, including 200 Ma and 1900 Ma. The Jurassic accretion complex juxtaposed between the Sanbagawa metamorphics and the Cretaceous zone is divided into three tectonostratigraphic units ; the Kazahaya-toge, Kamiyoshida and Kashiwagi. The boundaries among them and the other units are fault in contact.
The radiolarian biostratigraphic age of the Kazahaya-toge unit, consisting of alternation of sandst … More one and mudstone, is of late Early Jurassic to early Middle Jurassic, and is considered to have deposited in the forearc basin. The Kamiyoshida unit, consisting of sandstone and mudstone including exotic oceanic plate blocks of bedded chert, limestone and mafic volcanic and/or volpaniclastic rocks, is late Early to middle Middle Jurassic in age. This unit intercadates peculiar elastics layers including abundant apatite and phlogopite, probably derived from alkaline mafic igneous rocks. The K-Ar age of the phlogopite is approximately 250 Ma. The Kashiwagi unit is composed of alternation of pale-greenish grey slate, phyllitic black slate, dark grey siliceous slate, and grey to pale-green tuft, with subordinate amounts of bedded chert and limestone blocks. This unit is dominated in hemipelagic sediments. Schistose texture in the unit shows a metamorphic gradation to the late Jurassic Mikabu green rocks and also to the Sanbagawa metamorphic rocks. The blocks of the mafic rocks in the accretion complex have occupied primarily a part of late Paleozoic to early Mesozoic ocean floor. Their petrologic character and geologic age suggest that they were probably a part of an oceanic plateau formed in Izanagi plate. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Biju-Sekhar, S., M.K.Pandit, K.Yokoyama, M.Santosh: "Electron Microprobe dating of the Ajitgarh and Barodiya granitoids, NW India : Implications on the evolution of Dehli fold belt"Jour.Geosci.Osaka City Univ.. vol.45,no.12. 13-27 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yokoyama K., B.Zhou: "Preliminary study of ages of monazites in sands from the Yangtze River"Natn.Sci.Mus., Tokyo, Monograph. No.22. 83-88 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Santosh, M., K.Yokoyama, S.Biju-Sekhar, J.J.W.Rogers: "Multiple tectonothermal events in the granulite blocks of southern India revealed from EPMA dating : Implications on the history of supercontinents"Gondwana Research. Vol.6,no.1. 29-63 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Sekine, K., H.Iijima, Y.Saito: "Jurassic Radiolarians from the low-grade metamorphic zone of the Northern part of the Chichibu belt of the Kanto mountains, central Japan"Bull.Natn.Sci.Mus., Tokyo, Ser.C. Vol.27,nos.3/4. 101-108 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yokoyama, K., Y. Saito: "Provenance study of Pre-Tertiary sandstones in the Northern Kanto districts, central Japan"Mem.Natn.Sci.Mus., Tokyo. No.37. 7-20 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tsutsumi, Y., K.Yokoyama, K.Terada, Y.Sano: "SHRIMP U-Pb dating of zircons in sedimentary rocks from he Akiyoshi and Suo zones, southwest Japan"Jour.Mineral.Petrol.Sci.. Vol.95. 216-227 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 白尾元理, 小疇 尚, 斎藤靖二: "日本列島の20億年"岩波書店. 198 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Biju-Sekhar, S., K. Yokoyama, M. Santosh, M. K.Pandit, T. Okudaira, & M. Yoshida: "EPMA chemical ages of Paleoproterozoic granitoids from NW India and their significance"Gondwana Research. 4. 577-578 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hiroi, Y., E. S. Grew, Y. Motoyoshi, D. R. Peacoa, R.C. Rouse, S. Matsubara, K. Yokoyama, R. Miyawaki, J. J. McGee, S-C. Su, T. Hokada, N. Fukukawa & H.Shibasaki: "Ominelite, (Fe, Mg) Al_3BSiO_9 (Fe2+ analogue of grandidierite), a new mineral from porphyritic granite in Japan"American Mineralogist. 87 (1-2). 160-170 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Biju-Sekhar, S., M. K. Pandit, K. Yokoyama & M.Santosh: "Electron Microprobe dating of the Ajitgarh and Barodiya granitoids, NW India : Implications on the evolution of Dehli fold belt"Jour. Geosci. Osaka City Univ.. 45 (2). 13-27 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yokoyama K. & B. Zhou: "Preliminary study of ages of monazites in sands from the Yangtze River"Natn. Sci. Mus. Monograph. 22. 83-88 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Santosh, M., K. Yokoyama, S. Biju-Sekhar & J. J. W.Rogers: "Multiple tectonothermal events in the granulite blocks of southern India revealed from EPMA dating: Implications on the history of super-continents"Gondwana Research. 6 (1). 29-63 (2002)

    • Description
      「研究成果報告書概要(欧文)」より

URL: 

Published: 2004-04-14  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi