Nankai Trough, Kii transect (IODP drill sites)
SW Japan, off the Kii Peninsula, Japan
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NanTroSEIZE drill sites of the Nankai subduction zone, from the incoming plate to the Kumano forearc basin, down to 922 m below seafloor. Hüpers et al. (2016): B decreasing with depth down to 120 µM, by ash alteration (10B sink) and ammonium-driven desorption of exchangeable clay boron; δ11B from +15.2 to +49.2 ‰. Without coordinates in the paper.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 15.2 / 49.2 ‰ | 59 | pore water (dissolved boron), all sites Range and count for the whole study. Forearc basin (C0002, 17 analyses): increase to +44.2 ‰ near 200 m, plateau near +38.5 ‰ from 200 to 600 m, then +41 to +45 ‰ below 650 m. C0008A (slope, 5 analyses): up to +38.2 ‰ then +33.7 ‰ in the mass-transport deposit at 261 m. Per-site data in the neighbouring signatures where the text gives them. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 15.3 / 44.9 ‰ | 10 | pore water (dissolved boron), site C0011 (sedimentary inputs of the incoming plate) Continuous decrease with depth, from +44.9 ‰ at 404 m to +15.3 ‰ at 868 m; B up to 995 µM in volcanic and sandy turbidites. Lowest values ascribed to temperature-enhanced desorption near the basement. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 23.9 ‰ | 4 | pore water (dissolved boron), site C0006 (frontal thrust zone) Constant values near +23.9 ‰. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 27.8 / 35.3 ‰ | 6 | pore water (dissolved boron), site C0007 (frontal thrust zone) General increase with depth. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 20 / 31.1 ‰ | 6 | pore water (dissolved boron), site C0001 (megasplay fault zone) Scattered values. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 27.4 / 39.4 ‰ | 7 | pore water (dissolved boron), site C0004 (megasplay fault zone) General decrease with depth. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… | |
| 25.84 / 38.1 ‰ | 4 | pore water (dissolved boron), site C0008C (slope sediments at the megasplay tip) Increase from +25.84 ‰ at 18 m to +38.1 ‰ at 172 m, together with B: deep B-rich fluid rising through the underthrust slope sediments according to the authors. | Hüpers et al. (2016), Fluid flow and water-rock interaction across the active Nankai Trou… |
Deposits of the same type
Cite this page
IsoFind Atlas (2026). Nankai Trough, Kii transect (IODP drill sites), isotope signatures. https://www.isofind.tech/isotopes/en/sites/fosse-de-nankai-transect-de-kii-forages-iodp/ (accessed 2026-10-20).
@misc{isofind2026nankaitroughkiitransectiodpdr,
title = {Nankai Trough, Kii transect (IODP drill sites), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/sites/fosse-de-nankai-transect-de-kii-forages-iodp/},
note = {Accessed 2026-10-20}
}Updated : 2026-10-20