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Journal Articles

Depositional age constraint on channel sediments in an incised meandering river using feldspar OSL dating; A Case study in the Totsukawa River, Kii Mountains

Ogata, Manabu; Komatsu, Tetsuya; Nakanishi, Toshimichi

Dai Yonki Kenkyu, 60(2), p.27 - 41, 2021/06

no abstracts in English

Journal Articles

Formation process of swamp sediments of the Karako Lowland in northern Shimabara Peninsula, Western Japan

Nakanishi, Toshimichi*; Okuno, Mitsuru*; Yamasaki, Keiji*; Hong, W.*; Fujita, Natsuko; Nakamura, Toshio*; Horikawa, Yoshiyuki*; Sato, Eiichi*; Kimura, Haruo*; Tsutsumi, Hiroyuki*

Nagoya Daigaku Nendai Sokutei Kenkyu, 5, p.38 - 43, 2021/03

no abstracts in English

Oral presentation

Advanced examination technique for river erosion in inland area; A Case study of the Kii Peninsula, Japan

Nakanishi, Toshimichi; Komatsu, Tetsuya; Ogata, Manabu; Hosoya, Takashi*; Kaga, Takumi*

no journal, , 

no abstracts in English

Oral presentation

post-IR IRSL dating of fluvial deposits in abandoned river valley around cutoff spur in Kii Mountains

Ogata, Manabu; Komatsu, Tetsuya; Nakanishi, Toshimichi

no journal, , 

no abstracts in English

Oral presentation

Advanced technique for determining river incision rates in mountainous region based on dating of fluvial sediments around cutoff spurs

Nakanishi, Toshimichi; Komatsu, Tetsuya; Ogata, Manabu

no journal, , 

no abstracts in English

Oral presentation

Paleogeographical changes based on sedimentary facies analysis of drilling cores in the southern part of the Kinugawa lowland, central Japan

Miyamoto, Tatsuki*; Sugai, Toshihiko*; Kimori, Taiga*; Komatsu, Tetsuya; Nakanishi, Toshimichi

no journal, , 

no abstracts in English

Oral presentation

Sedimentary facies and radiocarbon ages of the alluvial-fan toes at the eastern foot of the Yoro Mountain

Hori, Kazuaki*; Nakanishi, Toshimichi; Hong, W.*; Nakashima, Rei*

no journal, , 

Event sediments by debris flows were evaluated based on the sedimentary facies and radiocarbon ages of four sediment cores from the eastern foot of the alluvial fan toes at the eastern foot of the Yoro Mountains. In addition, the marine reservoir effect (MRE) in the Holocene was measured by the offset of radiocarbon ages between terrestrial plant fragments and marine shell fragments found in the same stratum in the core sediments. On the results, nine coarse sediment were observed after 4070 cal BP in three cores. The average of MRE, ca 400 years (n = 13) and ca 330 years (n = 12), were identified on two cores.

Oral presentation

An Approach for estimating long-term (100,000-1,000,000 yr) incision rates of incised meandering river; A Case in Totsukawa River, Kii Mountains

Komatsu, Tetsuya; Ogata, Manabu; Nakanishi, Toshimichi; Kawamura, Makoto

no journal, , 

no abstracts in English

Oral presentation

Advanced examination technique for crustal deformation in stable area; A Case study of the Kanto Plain, Japan

Nakanishi, Toshimichi; Komatsu, Tetsuya; Hongo, Misao*; Noguchi, Marie*; Miyamoto, Tatsuki*; Kimori, Taiga*; Sugai, Toshihiko*

no journal, , 

no abstracts in English

Oral presentation

Offset in radiocarbon ages between marine bioclast and terrestrial plant pairs in the Holocene sediments along the Pacific coasts around Japan

Nakanishi, Toshimichi; Nanayama, Futoshi*; Hori, Kazuaki*; Niwa, Yuichi*; Komatsubara, Junko*; Kitamura, Akihisa*; Hong, W.*

no journal, , 

To identify chronological and spatial changes in the radiocarbon ($$^{14}$$C) marine reservoir effects, the $$^{14}$$C ages of eight pairs of marine shells and terrestrial plants were measured from the same horizons of one core of Holocene sediments around Japan. To determine the direct chronological changes of the marine reservoir effect between the Kuroshio and Oyashio Currents, radiocarbon ages were measured from the same stratigraphic horizons within Holocene sediment cores alomg the Pasific coast of Japan (eastern Hokkaido; Nanayama et al., 2003, Nanayama, 2020, Sanriku Coast; Niwa et al., 2017, 2019, Arakawa Lowland; Komatsubara et al., 2009, 2010, Shimizu Plain; Kitamura and Kobayashi, 2014; Nobi Plain) and Taiwan.

Oral presentation

High-resolution analysis of lake sediments collected from Lake Harutori in Kushiro City, eastern Hokkaido, Japan

Nakanishi, Toshimichi; Nanayama, Futoshi*; Katsuki, Kota*; Yamada, Keitaro*

no journal, , 

The Holocene sediments of Lake Harutori in Kushiro City, eastern Hokkaido, are mainly composed of annually laminated sediments, organic mud layers with plant fragments, sand layers with shell and plant fragments and tephra layers. Fluctuations of the marine reservoir effect of radiocarbon and the information on the paleo-tsunami caused by the huge interplate earthquakes were identified by the high-resolution sedimentological analysis.

Oral presentation

Geomorphic development in the coastal area of the Paleo-Tokyo Bay during the period from MIS 6 to MIS 5 based on sedimentary facies analysis of drilling cores

Miyamoto, Tatsuki*; Sugai, Toshihiko*; Kimori, Taiga*; Komatsu, Tetsuya; Nakanishi, Toshimichi

no journal, , 

no abstracts in English

Oral presentation

Geomorphic development of the Takaragi terrace since the Last Interglacial Period in the North Central Part of Kanto Plain, Japan

Kimori, Taiga*; Sugai, Toshihiko*; Miyamoto, Tatsuki*; Komatsu, Tetsuya; Nakanishi, Toshimichi

no journal, , 

no abstracts in English

Oral presentation

Depositional sequence of the Post-LGM incised-valley fill controlled by seismic crustal deformation and large-scale lahars; An Example of SKM core obtained from the Sukumo coastal lowland along the Nankai Trough, Japan

Nanayama, Futoshi*; Yamaguchi, Tatsuhiko*; Nakanishi, Toshimichi; Tsuji, Tomohiro*; Ikeda, Michiharu*; Kondo, Yasuo*; Miwa, Michiko*; Sugiyama, Shinji*; Kimura, Kazunari*

no journal, , 

The characteristics of the post-LGM incised valley fills and the depositional sequence were examined the SKM core collected in the Sukumo coastal lowland, where is expected to huge seismic subsidence due to the Nankai Trough great earthquakes. Our sedimentological, radiocarbon dating and paleoenvironmental results are as bellows. Sediments of the SKM core clearly show a succession influenced by post-glacial sea level change. The Matsuda River incised valley was formed in LGM and filled by fluvial sand and gravels in late Pleistocene. After the postglacial transgression, sea level reached -30 m (a.s.l.) at 9.8 ka and the incised valley changed to an estuary environment. The sea level continued to rise and it became an inner bay mud bottom environment, and reaching a maximum water depth was at 7.5 ka. The 7.3 ka Kikai caldera eruption in southern Kyushu caused heavy K-Ah ash fall in southwestern Shikoku, and then large-scale lahars frequently occurred immediately after the ash fall because of the vicinity of volcanic source. After ash fall, the K-Ah secondary sediments rapidly deposited on the inner bay environment and caused forced regression. After 7.0 ka, the growth of the delta became active ahead of the other regions, which may be due to the large K-Ah ash fall. At 5 ka, the sea level reached + 2.5 m (a.s.l.) estimated by the Sukumo midden and this altitude is recognized as the Holocene marine limit in this area. The information on relative sea level change during the past 10000 years has revealed that the Sukumo Bay area has not subsided due to seismic crustal deformation.

Oral presentation

Middle Holocene changes in relative sea-level on western Shikoku Island, Japan

Yamaguchi, Tatsuhiko*; Tsuji, Tomohiro*; Nanayama, Futoshi*; Nakanishi, Toshimichi; Ikeda, Michiharu*; Kondo, Yasuo*; Miwa, Michiko*; Hamada, Yohei*

no journal, , 

Shikoku Island is situated 150 km northwest of the Nankai trough that has developed in response to the convergence of the subducting Philippine Sea Plate and overriding Eurasian Plate. This tectonism causes deformation of the island, megathrust earthquakes, and tsunamis. Shikoku Island experiences coseismic and interseismic deformation. The middle Holocene tectonics of the island are still poorly understood. Relative sea-level (RSL) changes indicated by coastal sediments potentially record seismic uplift and subsidence. To infer RSL changes between 8 and 4 cal. kyr BP, we studied Holocene ostracode assemblages from the SKM drill core in Sukumo, southwest Shikoku Island (Tsuji et al., 2018, JpGU, MIS11-P19), and from six cores in the northern part of the island (Yasuhara et al., 2005, Palaeo3; Yasuhara and Seto, 2006, Paleontol. Res. 10). To estimate paleo-water depth and RSL, we employed the ostracode assemblages and modern analog technique. The SKM core is composed of conglomerate, ash, and mud chiefly. Its geological age was examined, using the $$^{14}$$C dating method (Nakanishi et al., 2019, Radiocarbon). The differences in RSL were identified across the island, possibly due to convergence of the Philippine Sea Plate.

Oral presentation

Radiocarbon ages of tsunami deposits from the Lake Harutori along the Pacific coast of Hokkaido, northern Japan

Shigeno, Kiyoyuki*; Nakanishi, Toshimichi; Hong, W.*; Nanayama, Futoshi*

no journal, , 

To estimate the sedimentary process of chronological samples in tsunami deposits, the radiocarbon ages of 10 pairs of marine shells and terrestrial plants were measured from one core obtained of lagoon lake sediments from the Lake Harutori in Kushiro City, eastern Hokkaido. This core of 12.6 meters length was obtained in the central part of the frozen lake in winter, which locates on a tectonic active region in the southwestern Kuril arc associated by the oblique subduction of the Pacific Plate under the Okhotsk. The radiocarbon ages from the tsunami deposits were more than 1000-4000 years older than the depositional curve constructed by previous radiocarbon ages and tephrochronology. It clearly suggests that these materials were reworked from older sediments by catastrophic tsunamis.

Oral presentation

Altitudinal distribution of the Last Interglacial Marine Formation in the central Kanto Plain, Japan

Miyamoto, Tatsuki*; Sugai, Toshihiko*; Komatsu, Tetsuya; Nakanishi, Toshimichi*; Niwa, Yuichi*; Hiura, Yuki

no journal, , 

no abstracts in English

Oral presentation

Landform evolution and estimation of crustal movement since MIS 12 in the central-northern part of the Kanto Plain

Miyamoto, Tatsuki*; Sugai, Toshihiko*; Niwa, Yuichi*; Nakanishi, Toshimichi*; Komatsu, Tetsuya; Hiura, Yuki

no journal, , 

no abstracts in English

Oral presentation

Environmental changes in the center of the Kanto plane around the Sashima and Takaragi uplands based on diatom analysis

Noguchi, Marie*; Miyamoto, Tatsuki*; Sugai, Toshihiko*; Nakanishi, Toshimichi*; Komatsu, Tetsuya; Suginaka, Yusuke*; Endo, Kunihiko*

no journal, , 

Discussions on the history of crustal development based on sedimentary facies analysis using the boring cores GC-NG-1, GC-OY-1, and GC-OY-2 in the central Kanto Plain, from the Sarushima Plateau to the Takaragi Plateau, are underway. In the study, paleoenvironmental restoration based on diatom analysis was performed. These core samples are likely to preserve sea-level changes and landing processes since MIS9. From the results of the diatom community analysis, the paleoenvironment in each core was found to change according to the boring site, such as inner bay, brackish water to freshwater, freshwater, lakes, river environment, and land environment. We also attempted to objectively present changes in community composition by cluster analysis of diatom analysis results.

Oral presentation

Estimation of emergence age using feldspar OSL dating; Case studies in the Noto Peninsula and the Oi River

Ogata, Manabu; Tsukahara, Yuzuko; Kawamura, Makoto; Kanno, Mizuho; Nishiyama, Nariaki*; Sueoka, Shigeru; Komatsu, Tetsuya; Nakanishi, Toshimichi*; Yasue, Kenichi*

no journal, , 

Optically stimulated luminescence (OSL) dating method on feldspar is useful to date sediments on geomorphological time scale. In this presentation, we present the case studies for marine terraces in the Noto Peninsula and abandoned river valleys along the Oi River, for which the emergence ages were estimated by using feldspar OSL dating. This study was carried out as a part of the establishment of advanced technology for estimation of uplift rates using emergence ages of emergent landforms project.

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