Abrupt Late Holocene uplifts of the southern Izu Peninsula,central Japan: Evidence from emerged marine sessile assemblages |
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| Authors: | Akihisa Kitamura Masato Koyama Koji Itasaka Yosuke Miyairi Hideki Mori |
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| Institution: | 1. Institute of Geosciences, Shizuoka University, , Shizuoka, 422‐8529 Japan;2. Center for Integrated Research and Education of Natural hazards, Shizuoka University, , Shizuoka, 422‐8529 Japan;3. Faculty of Education, Shizuoka University, , Shizuoka, 422‐8529 Japan;4. The Shizuoka Prefecture Government Office, , Shizuoka, 420‐8601 Japan;5. Atmosphere and Ocean Research Institute, University of Tokyo, , Chiba, 277‐8564 Japan;6. Division of Technical Service, Shizuoka University, , Shizuoka, 422‐8529 Japan |
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| Abstract: | Evidence for abrupt coastal uplifts has been found in emerged sessile assemblages in a sea cave at the southern end of the Izu Peninsula, central Japan. We identified five sessile assemblage zones: Zones I to V, in ascending order. The uppermost zone (Zone I), located at an elevation of 2.7–3.5 m above the present‐day mean sea level (amsl), is a hard massive shellcrust consisting mainly of the barnacles Chthamalus challenger and the tube worm Pomatoleios kraussii. Zone II, at 2.35–2.7 m amsl, is dominated by well‐preserved individuals of C. challenger. Zone III, at 2.0–2.35 m amsl, is strongly eroded and consists mainly of C. challenger and P. kraussii. Zone IV, at 1.6–2.0 m amsl, is characterized by the co‐occurrence of very fresh shells of C. challenger and P. kraussii. Zone V (the lowest zone), at 1.0–1.60 m amsl, is characterized by the co‐occurrence of very fresh shells of Saccostrea kegaki and P. kraussii, and by the absence of C. challenger. Radiocarbon dating by accelerator mass spectrometry (AMS) and the presence of modern taxa in the sessile assemblages suggest that three episodes of coastal uplift have occurred in the area, during AD 570–820, AD 1000–1270, and AD 1430–1660, with magnitudes of 0.9–2.0 m, 0.3–0.8 m, and 1.9–2.2 m, respectively. |
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| Keywords: | emerged sessile assemblages Holocene Izu Peninsula uplift events |
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