2024-03-29T14:49:57Z
https://u-ryukyu.repo.nii.ac.jp/oai
oai:u-ryukyu.repo.nii.ac.jp:02008853
2023-08-03T05:43:15Z
1642838163960:1642838338003
1642838403551:1642838406414
Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano
Toki, Tomohiro
Higa, Ryosaku
Ijiri, Akira
Tsunogai, Urumu
Ashi, Juichiro
Cold seep
Pore fluid
Nankai Trough
Accretionary prism
Kumano
Boron
Lithium
Clay mineral dehydration
Methane hydrate dissociation
We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in pore water extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ18OH2O and δDH2O values of the pore fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of pore fluids in the shallow sediments of the accretionary prism, which showed negative δ18OH2O and δDH2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, pore fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.
論文
http://purl.org/coar/resource_type/c_6501
Springer Open
2014
VoR
http://hdl.handle.net/20.500.12000/37652
1880-5981
Earth, Planets and Space
137
66
none
eng
https://doi.org/10.1186/s40623-014-0137-3
https://doi.org/10.1186/s40623-014-0137-3
open access