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1996 Fiscal Year Final Research Report Summary

Sulfur Isotopic Verification of Phanerozoic Ocean Anoxic Events

Research Project

Project/Area Number 06804028
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Petrology/Mineralogy/Science of ore deposit
Research InstitutionUniversity of Tsukuba

Principal Investigator

KAJIWARA Yoshimichi  University of Tsukuba, Institute of Geoscience, Professor, 地球科学系, 教授 (80015578)

Project Period (FY) 1994 – 1996
KeywordsSulfur Isotopes / Oceanic Anoxia / Isotope Fractionation / Bacteria / Sulfate Reduction / Sulfides / Paleoenvironment / Anaerobes
Research Abstract

Very recently, a sound sulfur isotopic oriterion for recognizing the ocean oxic-anoxic history has been proposed by the present investigator. It is based on information on microbial sulfur geochemistry obtained from some classical and latest examinations in natural and laboratory systems. The basis is the remarkable sulfur isotopic bimodalism in sedimentary and/or diagenetic sulfides recognized in the worldwide stratigraphic record. This bimodalism can most reasonably be accounted for by a drastic chage of environmental redox condition associated with discrimination of microbial habitat. In an aerobe-free anoxic basin where the sulfate reduction exclusively occurs because of the absence of any effective oxidants, the extent of 34S/32S fractionation of sulfide, with respect to contemporaneous seawater sulfate, shold be restricted within the currently confirmed range of kinetic isotope effect during dissimilatory sulfate reduction by anaerobic sulfur-reducing bacteria, that is, in the ra … More nge of -25 <double plus> 10 *. In an ordinary oxic basin where aerobes are relatively predominant, however, the extent of fractionation is expected to more or less exceed this range to give the values typically in the range of -50 <double plus> 10 * as generally observed in the modern oceanic sediments, since the initial sulfide once produced is reoxidized by aerobic sulfur-oxidizing bacteria or by other oxidants such as dissolved free oxygen and then incorporated in a sebsequent redox cycle during sedimentary and burial diagenetic processes. Thus, the isotopic composition of sedimentary and/or diagenetic sulfide provides a sound geochemical criterion for recognizing and reconstructing the oceanic oxic-anoxic hi
Applying this principle, an attempt has been made to evaluate paleoceanic redox settings of some important geologic events in Phanerozoic time. The results reveal that the mass extinctions and the stratabound type mineralizations in the world are almost always associated intimately with intense oceanic anoxia. This would provide a new additional constraint on modeling the earth history. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Kajiwara,Y.: "Ocean biogeochemical controls on the Kuroko oregenesis" Earth Science. 48(4). 299-315 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kajiwara,Y. 他4名: "Development of a largely anoxic strafified ocean and its temporary mussive mixing at the Permian/Triassic boundary" Palaeogeography Palaeoclimatology Palaeoecology. 111. 367-379 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 梶原良道: "大洋中央海嶺系の熱水噴気孔鉱床:深海熱水生態系に咲く徒花" 地質ニュース. 497. 34-45 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Mita,H.,Shimoyama,A.,Kajiwara,Y.: "Search for extraterrestrial amino acids in sediments at the Cretaceous/Terfiary boundary in Kawaruppu,Hokkaido,Japan" Geochemical Journal. 30(2). 89-98 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kamata,Y.Kajiwara,Y.: "Sulfur isotope data from the Permian/Triassic boundary in a chert sequence at Motogi,Gunma Prefecture,Japan" Geology and Paleontology of Japan and East Asia. Prof.Igo comn.Vol.19-27 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kaiho,K.,Kajiwara,Y.他11名: "Latest Paleocene benthic foraminiferal extinction and environmental changes at Tawanui,New Zealand" Paleogeography. 11(4). 447-465 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kajiwara, Y.: "Ocean biogeochemical controls on the Kuroko oreg enesis : A review" Earth Science. 48(4). 299-315 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kajiwara, Y., Yamakita, S., Ishida, K., Ishiga, H., Imai, A.: "Development of a largely anoxic stratified ocean and its temporary massive mixing at the Permian / Triassic boundary supported by the sulfur isotopic record." Palaeogeography Palaeoclimatology Palaeoecology. 111. 367-379 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kajiwara, Y.: "Hydrothermal vent ores in the mid-oceanic ridges : Transitory products of the deep-seahydrothermal ecosystems." Chishitsu News. 497 (in Japanese). 34-45 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Mita, H., Shimoyama, A., Kajiwara, Y.: "Search for extraterrestrial amino aids in sediments at the Cretaceous / Tertiary boundary in Kawaruppu, Hokkaido" Japan.Geochemical Journal. 30(2). 89-98 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kamata, Y., Kajiwara, Y.: "Geology and Paleontology of Japan and Southeast Asia (Noda, H., Sashida, K., eds.)" Sulfur isotopic data from the Permian-Triassic boundary in a chert sequence at Motegi, Gunma Prefecture, in the Ashio Terrane, central Japan.Professor Hisayoshi Igo Commemorative Volume. 19-27 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kaiho, K., Arinobu, T., Ishiwatari, R., Morgans, H.E.G., Okada, H., Takeda, N., Tazaki, K., Zhou, G., Kajiwara, Y., Matsumoto, R., Hirai, A., Niitsuma, N., Wada, H.: "Latest Paleocene benthic foraminiferal extinction and environmental changes at Tawanui, New Zealand." Paleogeography. 11(4). 447-465 (1996)

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

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Published: 1999-03-09  

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