| Project/Area Number |
10041124
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| Research Category |
Grant-in-Aid for Scientific Research (C).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
MORINAGA Hayao Himeji Institute of Technology, Faculty of Science, Associate Professor, 理学部, 助教授 (40210182)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Koshi Nagoya University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (70183689)
INOKUCHI Hiroo Himeji Institute of Technology, School of Humanities for Environmental Policy and Technology, Professor, 環境人間学部, 教授 (40112073)
劉 育燕 中国地質大学, 地球科学学院, 教授
殷 洪福 中国地質大学, 教授 学長
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | Permo-Triassic boundary / mass extinction / rock- and paleo-magnetism / rare earth elements (REE) / initial susceptibility / magnetostratigraphy / paleo-environment / marine regression / 磁気層序 / 古地磁気 / 地球化学 / 古生物 / 標準断面 |
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| Research Abstract |
We collected rock samples from several localities including Permo-Triassic (P/T) boundary for two years (1998 and 1999). P/T boundary is characterized by largest mass extinction. Fairly fresh rock samples from Meishan section of Changxing, Zhejiang Province were analyzed by rock-magnetic, paleomagnetic and geochemical approaches. Typical results are as follows :
(1) All the samples from parts of 3 m length including P/T biological boundary (Beds 22 to 30) show normal polarity, suggesting no polarity transition and no relationship between polarity reversal and mass extinction.
(2) Initial susceptibility and remanent magnetization intensity gradually increase from the lower position below P/T biological boundary to upper portion (upper part of Bed 24). This position corresponds to the starting time of the sedimentary environment change (increase of detrital deposits being supplied from the surrounding area). This is probably an evidence implying the relation to the global mass extinction.
(3) Pattern of rare earth elements (REEs) of collected samples may reflect the feature of paleo-ocean. As the result from ICP-Mass analysis, the REE pattern of carbonate fraction resembles that of silicate fraction well, suggesting the possibility of partition equilibrium between two fractions. Therefore, environment of paleo-ocean during the P/T transition can not be reconstructed using temporal variation of the REE pattern.
A remarkable conclusion is that paleo-ocean floor of Changxing area became gradually shallower (in other words, ocean surface became gradually lower) during the P/T transition. Further investigations are needed to establish which the phenomenon is global or regional.
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