2022 Fiscal Year Final Research Report
Stratigraphic correlation using tephra beds and calcareous nannofossil bioevents for understanding forearc tectonics
Project/Area Number |
20K14568
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Research Category |
Grant-in-Aid for Early-Career Scientists
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Allocation Type | Multi-year Fund |
Review Section |
Basic Section 17030:Human geosciences-related
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Research Institution | National Institute of Advanced Industrial Science and Technology |
Principal Investigator |
Utsunomiya Masayuki 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (10738313)
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | 石灰質ナノ化石 / テフラ / 不整合 / 層序 / 海底地すべり |
Outline of Final Research Achievements |
Forearc sedimentary basins developed in the southern Kanto region during the Late Cenozoic under the influence of plate subduction and collision tectonics. In this study, tephra and calcareous nannofossil are utilized to correlate geotectonic events between sedimentary basins. The detailed tephro- and calcareous nannofossil biostratigraphy were established from the upper Miura Group to the lower Kazusaa Group. As results, an erosional surface covered by submarine landslide deposits and pebbly sandstone layers was recognized just below the upper limit of the Mammoth reverse subcronozone (3.2 Ma), which can be recognized as a marker event indicating that the forearc basin was segmented east to west by the growth of local uplift zones. In addition, the tephra beds were correlated between the Chikura and Kazusa groups in the age interval of about 2.3 to 2.0 Ma.
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Free Research Field |
地質学
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Academic Significance and Societal Importance of the Research Achievements |
国内でも最も人口密度が高い地域の一つである南関東の基盤は後期新生代の前弧域で堆積した堆積層から成る.それらの地層は陸上に露出して直接特徴と年代を調査することが可能である.地質学的な時間スケールの堆積速度の変化や構造運動,不整合の形成との関係を明らかにすることで,しばしば大規模な地震被害に見舞われてきた南関東がどのような構造運動の元に発達してきたのかを理解することにつながる.また海底地すべり堆積物の研究から活動的な海底斜面の長期的な安定性を理解する上で知見が得られると期待される.
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