Uranium redistribution implied by 234U/238U disequilibrium study on apatite-bearing sedimentary rocks at Nakamaruke district, central Japan

1994 ◽  
Vol 9 (5) ◽  
pp. 547-552 ◽  
Author(s):  
Yutaka Kanai ◽  
Yukio Sakamaki
Keyword(s):  
Sedimentary Rocks ◽  
Central Japan

scholarly journals Geology and age of the Neogene sedimentary rocks in the Ituskaichi Basin, central Japan

1990 ◽  
Vol 96 (9) ◽  
pp. 759-770_1 ◽  
Author(s):  
Toshiaki IRIZUKI ◽  
Masaki TAKAHASHI ◽  
Yuichiro TANAKA ◽  
Motoyoshi ODA
Keyword(s):  
Sedimentary Rocks ◽  
Central Japan

The Redox Environment of Deep Groundwaters Associated with the Tono Uranium Deposit, Japan

2002 ◽  
Vol 713 ◽  
Author(s):  
Randy Arthur ◽  
Teruki Iwatsuki ◽  
Katsuhiro Hama ◽  
Kenji Amano ◽  
Richard Metcalfe ◽  
...  
Keyword(s):  
Uranium Deposit ◽  
Sedimentary Rocks ◽  
Redox Potentials ◽  
Central Japan ◽  
Flow Models ◽  
The Past ◽  
Oxidation Reduction ◽  
Reversible Redox ◽  
Approximate Location

ABSTRACTAn unconformity underlying the Tono uranium deposit in central Japan represents the approximate location of a redox front separating relatively oxidizing groundwaters (Eh ≈0 mV) in the weathered, fractured Toki granite (TG) from strongly reducing pore fluids (Eh ≈-360 mV) in sedimentary rocks of the overlying Lower Toki Lignite-bearing Formation (TL). Uranium has been effectively immobilized in the TL during the past 10 million years. Stable and reversible redox potentials measured in-situ in boreholes penetrating the sedimentary rocks and granite appear to be controlled by the Fe(III)-oxyhydroxide – Fe2+ redox couple. A simplified analytical model of front migration suggests that chemical buffering by pyrite alone would limit the propagation velocity of the front into the TL to less than 8x10−6 m yr−1. The model is constrained by Darcy fluxes derived from groundwater flow models and relative 14C groundwater ages, average modal abundances of pyrite in the TL, and the analytical detection limit for dissolved oxygen in TG groundwaters (2 ppm). Model results also suggest that the redox buffering capacity of the TL would be exhausted within 10 million years if an upper bound O2(aq) concentration in TG groundwaters fixed by equilibrium with atmospheric O2(g) (8.5 ppm) is assumed. Immobilization of uranium in the TL is thus attributable to oxidation-reduction reactions that minimize O2(aq) concentrations primarily in the TG, and secondarily in the TL.

Carbon-14 study of groundwater in the sedimentary rocks at the Tono study site, central Japan

2001 ◽  
Vol 16 (7-8) ◽  
pp. 849-859 ◽  
Author(s):  
T. Iwatsuki ◽  
S. Xu ◽  
Y. Mizutani ◽  
K. Hama ◽  
H. Saegusa ◽  
...  
Keyword(s):  
Sedimentary Rocks ◽  
Central Japan ◽  
Carbon 14
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