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1997 Fiscal Year Final Research Report Summary

Isotopic anomalies at the Precambrian-Cambrian boundary

Research Project

Project/Area Number 07041094
Research Category

Grant-in-Aid for international Scientific Research

Allocation TypeSingle-year Grants
SectionField Research
Research Field Geology
Research InstitutionThe University of Tokyo

Principal Investigator

MATSUMOTO Ryo  UNIVERSITY OF TOKYO,Graduate School of Sciences, Professor, 大学院・理学系研究科, 教授 (40011762)

Co-Investigator(Kenkyū-buntansha) ウッシュマンド A.  イラン地球科学技術研究所, 所長
UENO Katsumi  Tsukuba Univ., Institute of Geoscience, Lecturer, 地球科学系, 講師 (90241786)
KANO Akihiro  Hiroshima Uni., Faculty of Science, Assistant, 理学部, 助手 (60231263)
KAKUWA Yoshitaka  UNIVERSITY OF TOKYO,Graduate School Arts and Sciences, Assistant, 大学院・総合文化研究科, 助手 (70124667)
HUSHMAND A.  Research Institute of Earth Sciences, Director
Project Period (FY) 1995 – 1997
KeywordsPrecambrian / Cambrian boundary / Cambrian explosion / F / F boundary / Carbon isotope / Rare earth elements / Cerium anomaly / Redox potential
Research Abstract

This project was originaly intended to elucidate the nature of the Precambrian/Cambrian boundary event. However, the actual field work plans were reorganized and expanded towards the entire Paleozoic sections in the course of the joint study with the Iranian geologist group. Because the P/C boundary event was believed to be characterized only through the comparison with the other Paleozoic boundary events such as F/F boundary and P/T boundary. We have obtained the following major results concerning the chemo-stratigraphy and environmental changes of the Paleozoic world.
1. Negative and positive carbon isotopic anomaly have been recognized just below and bove the P/C boundary. The formaer and the latter are interpreted to correspond to mass extinction of Precambrian fauna and explosive diversification of the Paleozoic type fauna. Moreover, strong positive anomaly was observed in the late Cambrian strata.
2. Moderate negative carbon anomaly in the upper Devonian is probably attributed to the Famenian/Frasnian boundary events.
3. Cyclic changes in carbon isotopic composition recognized in the Carboniferous-Permian may reflect the glacier-interglacier cycles.
4. Chondrite-normalized REEs patterns show interesting secular variations. Strong negative Ce anomaly occurs in the Cambrian explosion intervals whereas the remaining Paleozoic sections show normal pattern, suggesting that the Cambrian explosion was associated with oxygenated ocean while the entire Paleozoic ocean was characrerized by reducing environment.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Matsumoto, R et al.: "Preliminary study of paleomagnetic study on the Cambrian" Jouv.Fat.Sci.Univ.Tokyo,SecII. 22. 233-249 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kimura, Matsumoto: "The Vendian-Cambrian S^<13>Crecord,Uorth Iran" E.P.S.L.147. 1-7 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kakuwa, Y: "P-T mass extindion recorded in bedded chert" Paleogeogr.Paleodimat.Paleoecol.121. 35-51 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 角和 善隆 他: "層状チャート相P/T境界付近でのIr異常の未検出" 地質学雑誌. 102. 139-142 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kano, A et al.: "The upper Jurassic-Lower Cretuceous carbonate" Sedimentary Geology. 99. 165-178 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ueno, K.: "Mesoschubertella from Hu Akiyoshi Limestone" Bull,Akiyoshi-dai Mus.Nat.Hist. 31. 21-31 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Matsumoto, r., Zhong Zheng, Kakuwa, Y., Hamdi, B., and Kimura, H.: "Preliminary results of paleomagnetic study on the Cambrian to the Triassic rocks of the Alborz, Northeaast Iran" Jour.Fac.Sci., Univ.of Tokyo, Sec.II. 22. 233-249 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kimura, H., Matsumoto, R., Hamdi, B., and Kakuwa, Y.: "The Vendian-Cambrian delta 13 C record" North Iran.E.P.S.L.147. 1-7 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshitaka Kakuwa: "Permian-Triassic mass extinction event recorded in bedded chert sequence in southwest Japan" Palaeogeogr.Palaeoclimat.Palaeoecol. 121. 35-51 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kakuwa, Y., Toyoda, K.: "Ir-anomaly is not detected at the P/T boundary of bedded chert facies (in Japanese)" Jour.Geol.Soc.Japan. 102. 139-142 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kano, A.and Jiju, K.: "The upper Jurassic-Lower Cretaceous carbonate-terrigenous succession and the development of carbonate mound in western Shikoku, Japan" Sedimentary Geology. 99. 165-178 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ueno, K.: "Mesoschuberetella (Permian Fusulinacea) from the Akiyoshi L imestone Group, southnwest Japan" Bull.Akiyoshi-dai Mus.Nat.Hist.no.31. 21-31 (1996)

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

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Published: 1999-03-16  

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