{"title":"日本南开海槽附近四国岛中全新世相对海平面变化与垂直构造地壳运动","authors":"Tatsuhiko Yamaguchi, Futoshi Nanayama, Toshimichi Nakanishi, Tomohiro Tsuji, Michiharu Ikeda, Yasuo Kondo, Michiko Miwa, Yohei Hamada","doi":"10.1111/iar.12452","DOIUrl":null,"url":null,"abstract":"<p>The Philippine Sea plate subducts beneath the Eurasia plate at the Nankai Trough, northwestern Pacific, causing crustal deformation, mega-thrust earthquakes, and tsunami events. Shikoku Island, 150 km northwest of the trough, experiences both coseismic and interseismic deformation. Coastal sediments potentially record vertical crustal movements as relative sea level (RSL) changes. We studied sedimentary facies and microfossil ostracodes in core SKM from southwestern Shikoku Island for evidence of middle Holocene tsunami events and deformation. The core sediments included nine event layers corresponding to storm or tsunami events. Using modern analog techniques, we estimated RSLs from the ostracode assemblages of core SKM and 13 other cores from Shikoku Island and the surrounding region. Then, we subtracted RSL changes due to glacio-hydro isostatic adjustment from the estimated RSLs to estimate vertical tectonic movement rates in these cores between 8.6 and 4.7 ka. The inferred RSL changes suggest that the Sukumo site has experienced both uplift and subsidence since 8.6 ka. Before 6.6 ka, rates of tectonic crustal movement were higher than the modern-day rate, and its spatial distribution also differed. After 6.6 ka, tectonic crustal movement showed a similar spatial pattern and occurred at rates close to the modern day interseismic rate. The spatial pattern and rates of tectonic crustal movement could be caused by changes in rupture areas between the Eurasia and the Philippine Sea plates beneath the Shikoku Island and in stress condition of the asthenosphere. Some of the vertical displacements can be explained by the movements of local active faults.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2022-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan\",\"authors\":\"Tatsuhiko Yamaguchi, Futoshi Nanayama, Toshimichi Nakanishi, Tomohiro Tsuji, Michiharu Ikeda, Yasuo Kondo, Michiko Miwa, Yohei Hamada\",\"doi\":\"10.1111/iar.12452\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The Philippine Sea plate subducts beneath the Eurasia plate at the Nankai Trough, northwestern Pacific, causing crustal deformation, mega-thrust earthquakes, and tsunami events. Shikoku Island, 150 km northwest of the trough, experiences both coseismic and interseismic deformation. Coastal sediments potentially record vertical crustal movements as relative sea level (RSL) changes. We studied sedimentary facies and microfossil ostracodes in core SKM from southwestern Shikoku Island for evidence of middle Holocene tsunami events and deformation. The core sediments included nine event layers corresponding to storm or tsunami events. Using modern analog techniques, we estimated RSLs from the ostracode assemblages of core SKM and 13 other cores from Shikoku Island and the surrounding region. Then, we subtracted RSL changes due to glacio-hydro isostatic adjustment from the estimated RSLs to estimate vertical tectonic movement rates in these cores between 8.6 and 4.7 ka. The inferred RSL changes suggest that the Sukumo site has experienced both uplift and subsidence since 8.6 ka. Before 6.6 ka, rates of tectonic crustal movement were higher than the modern-day rate, and its spatial distribution also differed. After 6.6 ka, tectonic crustal movement showed a similar spatial pattern and occurred at rates close to the modern day interseismic rate. The spatial pattern and rates of tectonic crustal movement could be caused by changes in rupture areas between the Eurasia and the Philippine Sea plates beneath the Shikoku Island and in stress condition of the asthenosphere. Some of the vertical displacements can be explained by the movements of local active faults.</p>\",\"PeriodicalId\":14791,\"journal\":{\"name\":\"Island Arc\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.0000,\"publicationDate\":\"2022-06-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Island Arc\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/iar.12452\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Island Arc","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/iar.12452","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan
The Philippine Sea plate subducts beneath the Eurasia plate at the Nankai Trough, northwestern Pacific, causing crustal deformation, mega-thrust earthquakes, and tsunami events. Shikoku Island, 150 km northwest of the trough, experiences both coseismic and interseismic deformation. Coastal sediments potentially record vertical crustal movements as relative sea level (RSL) changes. We studied sedimentary facies and microfossil ostracodes in core SKM from southwestern Shikoku Island for evidence of middle Holocene tsunami events and deformation. The core sediments included nine event layers corresponding to storm or tsunami events. Using modern analog techniques, we estimated RSLs from the ostracode assemblages of core SKM and 13 other cores from Shikoku Island and the surrounding region. Then, we subtracted RSL changes due to glacio-hydro isostatic adjustment from the estimated RSLs to estimate vertical tectonic movement rates in these cores between 8.6 and 4.7 ka. The inferred RSL changes suggest that the Sukumo site has experienced both uplift and subsidence since 8.6 ka. Before 6.6 ka, rates of tectonic crustal movement were higher than the modern-day rate, and its spatial distribution also differed. After 6.6 ka, tectonic crustal movement showed a similar spatial pattern and occurred at rates close to the modern day interseismic rate. The spatial pattern and rates of tectonic crustal movement could be caused by changes in rupture areas between the Eurasia and the Philippine Sea plates beneath the Shikoku Island and in stress condition of the asthenosphere. Some of the vertical displacements can be explained by the movements of local active faults.
期刊介绍:
Island Arc is the official journal of the Geological Society of Japan. This journal focuses on the structure, dynamics and evolution of convergent plate boundaries, including trenches, volcanic arcs, subducting plates, and both accretionary and collisional orogens in modern and ancient settings. The Journal also opens to other key geological processes and features of broad interest such as oceanic basins, mid-ocean ridges, hot spots, continental cratons, and their surfaces and roots. Papers that discuss the interaction between solid earth, atmosphere, and bodies of water are also welcome. Articles of immediate importance to other researchers, either by virtue of their new data, results or ideas are given priority publication.
Island Arc publishes peer-reviewed articles and reviews. Original scientific articles, of a maximum length of 15 printed pages, are published promptly with a standard publication time from submission of 3 months. All articles are peer reviewed by at least two research experts in the field of the submitted paper.