Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy
Abstract The basement of the Tokyo metropolitan area consists of the Miocene–Pleistocene forearc basin fills that are well exposed around Tokyo Bay, especially on the Miura and Boso peninsulas. The forearc basin fills on these two peninsulas are called the Miura and Kazusa groups, and they were depo...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2023-05-01
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| Series: | Progress in Earth and Planetary Science |
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| Online Access: | https://doi.org/10.1186/s40645-023-00558-y |
| _version_ | 1797817683809402880 |
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| author | Masayuki Utsunomiya Itoko Tamura Atsushi Nozaki Terumasa Nakajima |
| author_facet | Masayuki Utsunomiya Itoko Tamura Atsushi Nozaki Terumasa Nakajima |
| author_sort | Masayuki Utsunomiya |
| collection | DOAJ |
| description | Abstract The basement of the Tokyo metropolitan area consists of the Miocene–Pleistocene forearc basin fills that are well exposed around Tokyo Bay, especially on the Miura and Boso peninsulas. The forearc basin fills on these two peninsulas are called the Miura and Kazusa groups, and they were deposited during the late Miocene–Pliocene and Pliocene–middle Pleistocene, respectively. Because many biostratigraphic datum planes, paleomagnetic reversal events, and other chronostratigraphic tools are available for these deposits, they provide the “type stratigraphy” of other equivalent sedimentary sequences on the Japanese islands and in the northwest Pacific. However, the use of such stratigraphic markers has not been fully applied to understand the architecture of a basin-wide unconformity between the Miura and Kazusa groups called the Kurotaki unconformity. For our study, we made correlations among the Pliocene vitric tephra beds based on their stratigraphic levels, lithologic characteristics, the chemical compositions of glass shards, and calcareous nannofossil biostratigraphy. As a result, we were able to correlate tephra beds Ng-Ky25 just above the C3n.3n normal subchronozone (4.7 Ma), IkT16-An157.5 and IkT19-An158.5 near the top of the Mammoth reverse polarity subchronozone (3.21 Ma), and Ahn-Onr (2.6–2.7 Ma) across Tokyo Bay on the Miura and Boso peninsulas. We were able to recognize erosional surfaces and coeval mass-transport deposits immediately below the top of the Mammoth reverse polarity subchronozone, which suggests that submarine landslide(s) may have produced the lack of stratigraphic horizons (4.5–3.2 Ma) in the Miura and eastern Boso regions. Basal pebbly sandstone beds pervasively cover the erosional surfaces, and they show lateral variations into the thick (up to 60 m) mass-transport deposits and overlying turbidite sandstones. The lateral variations in sediment thickness of the post-failure deposits suggest that the basin-wide erosion was associated with the initial growth of a basin-bounding structural high that separates two distinct sub-basins in the forearc basin, which resulted in the subsequent onlapping deposition in the earliest stage of the Kazusa forearc basin. The basin-wide erosion marks the initiation of tectonic reconfigurations that led to segmentation of the forearc basin around the Tokyo Bay region. |
| first_indexed | 2024-03-13T08:57:05Z |
| format | Article |
| id | doaj.art-188ee81a77ba4ee4865f8486579caa8c |
| institution | Directory Open Access Journal |
| issn | 2197-4284 |
| language | English |
| last_indexed | 2024-03-13T08:57:05Z |
| publishDate | 2023-05-01 |
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| spelling | doaj.art-188ee81a77ba4ee4865f8486579caa8c2023-05-28T11:31:00ZengSpringerOpenProgress in Earth and Planetary Science2197-42842023-05-0110112610.1186/s40645-023-00558-yBasin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphyMasayuki Utsunomiya0Itoko Tamura1Atsushi Nozaki2Terumasa NakajimaResearch Institute of Geology and Geoinformation, Geological Survey of Japan, AISTChuo UniversityHiratsuka City MuseumAbstract The basement of the Tokyo metropolitan area consists of the Miocene–Pleistocene forearc basin fills that are well exposed around Tokyo Bay, especially on the Miura and Boso peninsulas. The forearc basin fills on these two peninsulas are called the Miura and Kazusa groups, and they were deposited during the late Miocene–Pliocene and Pliocene–middle Pleistocene, respectively. Because many biostratigraphic datum planes, paleomagnetic reversal events, and other chronostratigraphic tools are available for these deposits, they provide the “type stratigraphy” of other equivalent sedimentary sequences on the Japanese islands and in the northwest Pacific. However, the use of such stratigraphic markers has not been fully applied to understand the architecture of a basin-wide unconformity between the Miura and Kazusa groups called the Kurotaki unconformity. For our study, we made correlations among the Pliocene vitric tephra beds based on their stratigraphic levels, lithologic characteristics, the chemical compositions of glass shards, and calcareous nannofossil biostratigraphy. As a result, we were able to correlate tephra beds Ng-Ky25 just above the C3n.3n normal subchronozone (4.7 Ma), IkT16-An157.5 and IkT19-An158.5 near the top of the Mammoth reverse polarity subchronozone (3.21 Ma), and Ahn-Onr (2.6–2.7 Ma) across Tokyo Bay on the Miura and Boso peninsulas. We were able to recognize erosional surfaces and coeval mass-transport deposits immediately below the top of the Mammoth reverse polarity subchronozone, which suggests that submarine landslide(s) may have produced the lack of stratigraphic horizons (4.5–3.2 Ma) in the Miura and eastern Boso regions. Basal pebbly sandstone beds pervasively cover the erosional surfaces, and they show lateral variations into the thick (up to 60 m) mass-transport deposits and overlying turbidite sandstones. The lateral variations in sediment thickness of the post-failure deposits suggest that the basin-wide erosion was associated with the initial growth of a basin-bounding structural high that separates two distinct sub-basins in the forearc basin, which resulted in the subsequent onlapping deposition in the earliest stage of the Kazusa forearc basin. The basin-wide erosion marks the initiation of tectonic reconfigurations that led to segmentation of the forearc basin around the Tokyo Bay region.https://doi.org/10.1186/s40645-023-00558-yForearc basin fillKazusa groupKurotaki unconformitymass-transport depositMiura groupPliocene |
| spellingShingle | Masayuki Utsunomiya Itoko Tamura Atsushi Nozaki Terumasa Nakajima Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy Progress in Earth and Planetary Science Forearc basin fill Kazusa group Kurotaki unconformity mass-transport deposit Miura group Pliocene |
| title | Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy |
| title_full | Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy |
| title_fullStr | Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy |
| title_full_unstemmed | Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy |
| title_short | Basin-wide erosion and segmentation of the Plio-Pleistocene forearc basin in central Japan revealed by tephro- and biostratigraphy |
| title_sort | basin wide erosion and segmentation of the plio pleistocene forearc basin in central japan revealed by tephro and biostratigraphy |
| topic | Forearc basin fill Kazusa group Kurotaki unconformity mass-transport deposit Miura group Pliocene |
| url | https://doi.org/10.1186/s40645-023-00558-y |
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