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An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan
Joint Authors
Miyakawa, Kazuya
Nakata, Kotaro
Hasegawa, Takuma
Oyama, Takahiro
Ishii, Eiichi
Sasamoto, Hiroshi
Source
Issue
Vol. 2018, Issue 2018 (31 Dec. 2018), pp.1-21, 21 p.
Publisher
Hindawi Publishing Corporation
Publication Date
2018-01-18
Country of Publication
Egypt
No. of Pages
21
Main Subjects
Abstract EN
A groundwater dating for very old porewater using 36Cl and 4He was applied to the Koetoi and Wakkanai formations distributed in the northernmost part in Japan.
Measured 36Cl/Cl in the Koetoi Formation was 2.6 ± 2.0 × 10−15 and that in the Wakkanai Formation was 8.1 ± 2.5 × 10−15.
These values are similar to 36Cl/Cl in situ secular equilibrium calculated from chemical compositions of core suggesting that Cl− ions and porewater have remained in the formations for much longer than half-life of 36Cl .
He concentration in porewater ranged from 1.1 × 10−6 to 2.6 × 10−5 (ccSTP gw-1) and it is much higher than water saturated with air indicating that both formations contain very old porewater.
However, the possibility of mixing of young water was indicated because He concentration was lower than that calculated by multiplication of in situ He production and time after the uplift.
This possibility was also supported by Cl−, δD, and δ18O data.
After combining information on 36Cl/Cl, 4He, and δD and δ18O, it was inferred that the porewater in the deep part of the Wakkanai Formation might have been stagnant since the uplift.
The porewater in the Koetoi Formation and the shallow part of the Wakkanai Formation were found to be affected by young surface water.
American Psychological Association (APA)
Nakata, Kotaro& Hasegawa, Takuma& Oyama, Takahiro& Ishii, Eiichi& Miyakawa, Kazuya& Sasamoto, Hiroshi. 2018. An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan. Geofluids،Vol. 2018, no. 2018, pp.1-21.
https://search.emarefa.net/detail/BIM-1158527
Modern Language Association (MLA)
Nakata, Kotaro…[et al.]. An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan. Geofluids No. 2018 (2018), pp.1-21.
https://search.emarefa.net/detail/BIM-1158527
American Medical Association (AMA)
Nakata, Kotaro& Hasegawa, Takuma& Oyama, Takahiro& Ishii, Eiichi& Miyakawa, Kazuya& Sasamoto, Hiroshi. An Evaluation of the Long-Term Stagnancy of Porewater in the Neogene Sedimentary Rocks in Northern Japan. Geofluids. 2018. Vol. 2018, no. 2018, pp.1-21.
https://search.emarefa.net/detail/BIM-1158527
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references
Record ID
BIM-1158527