Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nakanishi, Toshimichi*; Komatsu, Tetsuya; Ogata, Manabu; Kawamura, Makoto; Yasue, Kenichi*
Gekkan Chikyu "Kiso deta Kara Kangaeru Dai Yonkigaku No Shintenkai-I" Gogai No.71, p.148 - 155, 2022/02
The formation process of terrace topography was investigated by observing and analyzing boring core samples collected in the middle reaches of the Kumano River. It was assumed that the older terrace topography was distributed higher than the current riverbed surface. However, since tributary debris flow deposits may be thickly distributed beneath the old gyre river valley, care must be taken when using the surface of the ground as an index of uplift and erosion.
*; Fuse, Keisuke*; *; Yasuda, Kenya*
PNC TJ7454 97-001, 536 Pages, 1997/03
no abstracts in English
Takano, Toyoji*; Sasaki, Yutaka*; Fuse, Keisuke*; Saito, Akira*; Sato, Yoshikazu*
PNC TJ1454 96-001, 295 Pages, 1996/03
None
Tokuyasu, Kayoko; Tamura, Itoko; Komatsu, Tetsuya; Yasue, Kenichi
no journal, ,
The uplift rate during the past hundred thousand years is estimated from the elevation and emergence ages of terrace surfaces which are used as geomorphologic standard. OSL dating is effective method to determine the emergence ages. Here we report a case study of quartz OSL dating of fluvial terrace sediments, and its adequacy is considered in the correlation with intercalated marker tephra. All samples were collected from fluvial terrace sediments along Kiso River and Tsukechi River which is a tributary of the Kiso. The investigated fluvial terrace sediments are composed of laminated sand layer and pumice layer which is likely to be reworked. The pumice was identified as On-Pm1 tephra by mineral composition, refractive indices of volcanic glass and phenocryst minerals, and the major element composition of volcanic glass. This indicated that the fluvial terrace sediments were deposited after 100ka. The extracted quartz grains from terrace sediments were measured by conventional SAR protocol. The obtained OSL ages are about 40-50 ka, being underestimated because the OSL decay curves from all samples were dominant by medium component which is unsuitable for OSL dating. We thus attempt to determine the equivalent dose using the isolated fast component OSL signal which is suitable for OSL dating.
Komatsu, Tetsuya; Izumida, Atsuto*; Takahashi, Takayuki*; Funatsu, Taro*; Muraki, Masahiro*; Hozo, Renya*; Nomura, Katsuhiro; Niwa, Masakazu; Sugai, Toshihiko*
no journal, ,
no abstracts in English
Hiura, Yuki; Komatsu, Tetsuya; Sugai, Toshihiko*
no journal, ,
no abstracts in English
Komatsu, Tetsuya; Hiura, Yuki; Takahashi, Takayuki*; Funatsu, Taro*; Muraki, Masahiro*; Kimori, Taiga*; Sugai, Toshihiko*
no journal, ,
no abstracts in English
Takai, Shizuka; Sanga, Tomoji*; Shimada, Taro; Takeda, Seiji
no journal, ,
Understanding long-term future landscape evolution is indispensable for safety assessment for radioactive waste disposal. River incision can be modelled through a slope-area analysis, in which the channel profiles are compared with the bedrock river incision model (stream power model). Not only the section of bedrock river, tectonic uplift or bedrock geology can be inferred from the analysis. In addition, if these conditions are spatially uniform, the river incision model can be parameterized using basin-scale denudation rates estimated using terrestrial cosmogenic nuclides (TCN). However, since the measurement of TCN needs quartz samples, the applicability of slope-area analysis to parameterize the river incision parameters has not been confirmed in sedimentary rock area. In this study, we conducted the slope-area analysis on the Kamikita coastal plain (sedimentary rock), where the denudation rate can be estimated from marine terraces widely distributed in this area. For 50 channels, log S (channel slope) and log A (drainage area) were linearly regressed in the upstream region, which is equal to the stream power model. Moreover, the estimated parameters of river incision model based on the marine terraces were within the range of the estimated parameters in previous studies based on TCN. Accordingly, the form and parameterization of river incision model can be implemented through the slope-area analysis in sedimentary rock area.
