Fluctuations of fossil pollen asseemblages from the Okute Basin, Mizunami City, Gifu Prefecture, Central Japan; Vegetation and climate records since marine isotope stage 9

Morita, Yoshimune*; Kamiya, Chiho*; Sasaki, Toshinori*; Miyagi, Toyohiko*; Sugai, Toshihiko; Yanagida, Makoto*; Furusawa, Akira*; Fujiwara, Osamu*

Kikan Chirigaku, 62(4), p.195 - 210, 2010/12

http://ci.nii.ac.jp/naid/40018701773

It is assumed that the variation of temperature and the precipitation with the climate change may affect geological environment such as the subsurface water flow. Therefore, as well as global climate change from the past to the present, investigation technology to grasp local climate change is indispensable. A palynological study was carried out using the sediment core taken from the Okute Basin, located in the northeast of Mizunami Underground Research Laboratory. As a result, it was appeared that in a interglacial epoch, there was much precipitation around this area, and that in a glacial epoch, became colder and more arid, compared with Kinki region in the same latitude. This shows that the modern analog method with pollen data from the sediment of the inland basin is effective technique to estimate a local climate change.

Development of the Kiso river delta during the last 10,000 years based on analyses of sedimentary cores and C datings

Ogami, Takashi*; Sugai, Toshihiko*; Fujiwara, Osamu*; Yamaguchi, Masaaki*; Sasao, Eiji

Chigaku Zasshi, 118(4), p.665 - 685, 2009/00

https://doi.org/10.5026/jgeography.118.665

The depositional process of the latest Pleistocene to Holocene shallow marine and fluvial sequences is investigated by using five drill cores from the Kiso river delta, central Japan. Based on facies analysis, the sediments were classified into 5 units; A: basal gravel, B: fluvial to intertidal sand and silt, C: transgressive lag deposit, prodelta mud or sandy silt, D: delta-front-slope sandy silt or sand, delta-front-platform sand, E: delta-plain to fluvial sand and silt. Detailed age-depth curves of each cores are reconstructed based on 107 AMS C ages. The curves are divided into four sections; I: mainly consists of unit B with rapid accumulation (7.3-21.4 mm/yr), II: mainly consists of unit C with moderate accumulation (2.4-2.8 mm/yr), III: mainly consists of unit D with rapid accumulation (6.7-17.8 mm/yr), IV: consists of unit D and E with moderate accumulation (1.3-3.9 mm/yr). The section boundaries of I/II and II/III reflect inundation into the bay and achievement of progradational delta-front slope, respectively. The expanding rate of the bay is 10 m/yr during 10,200-7,900 cal yrs BP. The progradation rates of the delta are 3-4 m/yr (6.500-4,100 cal yrs BP), 5 m/yr (4,100-1,300 cal yrs BP), 10 m/yr (1,300 cal yrs BP to the present). These indicate the transition from transgression to regression occurred between 7,800 to 7,300 cal yrs BP. The geological cross section along the Kiso river coupled with isochrones indicates following history. (1) 10,000-7,280 cal yrs BP (K-Ah horizon): During the expansion of the bay, onlap of unit C on unit B is visible, and unit C overlapped all the core sites. (2) 7,280 cal yrs BP to present: Isochrones younger than 6,500 cal yrs BP are similar each other and cross unit boundaries of C/D and D/E. This demonstrates units C, D and E are contemporaneous heterotopic facies formed by progradational delta.

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

Current status of the geoscientific research for long-term stability of the geological environment in the JNC's R&D programme

Umeda, Koji; Osawa, Hideaki; Nohara, Tsuyoshi; Sasao, Eiji; Fujiwara, Osamu; Asamori, Koichi; Nakatsuka, Noboru

Genshiryoku Bakkuendo Kenkyu, 11(2), p.97 - 112, 2005/03

https://doi.org/10.3327/jnuce.11.97

This paper describes an overview of geotectonic events in Japan from the point of view of the long-term stability of geological environment. Moreover, the current status of research/prediction technologies developed by JNC is summarized.

Sedimentological time-averaging and C dating of marine shells

Fujiwara, Osamu; Kamataki, Takanobu*; Masuda, Fujio*

Nuclear Instruments and Methods in Physics Research B, 223-224, p.540 - 544, 2004/08

https://doi.org/10.1016/j.nimb.2004.04.101

The radiocarbon dating of sediments using marine shells involves uncertainties due to the mixed ages of the shells mainly attributed to depositional processes also known as sedimentological time-averaging. This stratigraphic disorder can be removed by selecting the well-preserved indigenous shells based on ecological and taphonomic criteria. These criteria on sample selection are recommended for accurate estimation of the depositional age of geologic strata from 14C dating of marine shells.

Regional distribution of erosion rates over the Japanese Islands

Fujiwara, Osamu; Sanga, Tomoji*; Omori, Hiroo*

JNC TN7410 2001-015, 29 Pages, 2001/08

JNC-TN7410-2001-015.pdf:1.49MB
JNC-TN7410-2001-015-appendix(CD-ROM).zip:2.07MB

Regional distribution of erosion rates has been studied to clarify the long-term stability of the geological environment in Japan. The regional distribution of erosion rates should be estimated to predict long-term geomorphological changes. This research is to estimate the distribution of erosion rates over the Japanese Islands based on the relationship between the sediment delivery rates to reservoirs and the dispersion of altitude of the drainage basins. The relationship between erosion rate E(mm/y) and dispersion of altitude D(m) of drainage basins is expressed by E=0.000044 D with a correlation coefficient of 0.94. This equation was used to calculate the denudation rate for each 6 km 6 ㎞ area of the Japanese Islands using a "digital map 50 m grid". The denudation rates are, highest in the central Japanese mountains ( 3-5 mm/y), moderate in the outer belt of Southwest Japan, the inner belt of Northeast Japan and Hokkaido ( 2-3 mm/y), and lowest in the inner belt of Southwest Japan, outer belt of Northeast Japan and central Hokkaido ( 1 mm/y). These regional characteristics are closely related to the distribution of Quaternary uplift rates, which caused the regional differences in surface topography.

River Deepening and Aggradation Estimated from Relative Heights of River Terraces

; Yanagida, Makoto*; Fujiwara, Osamu; Ozawa, Akio*

Chigaku Zasshi, 109(3), p.366 - 382, 2000/00

https://doi.org/10.5026/jgeography.109.3_366

None

Holocene Tsunami Deposits Detected by Drilling in Drowned Valleys of the Boso and Miura Peninsulas

Fujiwara, Osamu; Masuda, Fujio; Sakai, Tetsuya*; Irizuki, Toshiaki*; Fuse, Keisuke*

Dai Yonki Kenkyu, 38(1), p.41 - 58, 1999/02

None

None

Fujiwara, Osamu; Danhara, Toru*

Dai Yonki Kenkyu, 37(2), p.95 - 106, 1998/00

https://doi.org/10.4116/jaqua.37.95

None

None

Fujiwara, Osamu; Yamazaki, Haruo*; *

Chigaku Zasshi, , 

None