Otay (bentonite)
California, United States
Otherbentonite
- Type
- Bentonite (Mg, Ca)
Smectite bentonite deposit. Mainly marine deposition: distal shallow deltaic coastal lagoon setting, parent material rhyodacitic to trachytic pyroclastics; marine to brackish mixing, probably below 40 °C alteration; Eocene to Oligocene. Köster et al. (2019): δ11B of purified smectites and fluid δ11B calculated for trigonal or tetrahedral boron at 25 and 90 °C.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −2.9 ± 0.65 ‰ | −4.7 / −1.7 ‰ | smectite (< 0.2 µm) treated with mannitol Single sample, published mean and 2SD (uncertainty halved to 1σ): OT-M -2.9 (2SD 1.3, -4.7 to -1.7, 17.5 µg/g B). | Köster et al. (2019), The boron isotope geochemistry of smectites from sodium, magnesium … | |
| 1.8 ± 0.9 ‰ | −2 / 4.6 ‰ | smectite (< 0.2 µm) treated with mannitol and ammonium-exchanged, structural boron Single sample, published mean and 2SD (uncertainty halved to 1σ): OT-A +1.8 (2SD 1.8, -2.0 to +4.6, 16.0 µg/g B). | Köster et al. (2019), The boron isotope geochemistry of smectites from sodium, magnesium … |
Deposits of the same type
- Central African Copperbelt (whole province) DR Congo and Zambia
- Witwatersrand basin South Africa
- Stelvio Italy
- Oris Italy
- Kupferschiefer, Lubin-Sieroszowice district Poland
- Timna Israël
- Datangpo-type manganese (Gaolou, Minle, Zhenxing) China
- Eyller Bruch bog iron ore Germany
Cite this page
IsoFind Atlas (2026). Otay (bentonite), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/otay-bentonite/ (accessed 2026-10-20).
@misc{isofind2026otaybentoniteisotopesignature,
title = {Otay (bentonite), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/otay-bentonite/},
note = {Accessed 2026-10-20}
}Updated : 2026-10-20