2013 Fiscal Year Final Research Report
The beginning and the formation process of Kurotaki Unconformity base of the Kazusa Group, related to the origin of Kanto plain
| Project/Area Number |
23501246
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Geography
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
YAMAZAKI Haruo 首都大学東京, 都市環境科学研究科, 教授 (70260784)
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| Research Collaborator |
TAMURA Itoko 首都大学東京, 都市環境科学研究科, 客員研究員 (00722159)
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| Project Period (FY) |
2011 – 2013
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| Keywords | 黒滝不整合 / 上総層群 / 火山灰層序 / テフラ層序 / 関東平野 / 形成プロセス / 海底地すべり |
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| Research Abstract |
The Kurotaki Unconformity is a conspicuous geologic gap recognized at the base of Plio-Pleistocene Kazusa Group in Boso Peninsula. Various opinions such as structural movement or submarine landslide on the origin of the unconformity have been examined, but the clear answer is not provided. This study clarified the age of the strata covering the Kurotaki Unconformity at various places in Boso Peninsula through the identification and confirmation of chronological age of the wide spreded tephras intercalated in the Kazusa Group covering the unconformity. As a result, the author found that the sedimentation age of the base layer of Kazusa Group covering the Kurotaki Unconformity ranged from 3.2 to 1.9 Ma in Boso Peninsula, but there was no sedimentary gap between the Plio-Pleistocene Kazusa Group and Pliocen Miura Group in Miura Peninsula. From these facts, author regarded the Kurotaki Unconformity as the result of several local submarine landslides occurred sequentially in 2.3 - 1.9Ma.
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