Amazon, lower course (Óbidos)
Pará, Brazil
Rivers and surface water
- Type
- River or surface water
Dissolved silicon heavier than igneous rocks (-0.3 ± 0.3 ‰), a sign of fractionation during weathering and clay formation; the rivers studied by De La Rocha et al. (2000) give +0.8 ± 0.3 ‰ (n = 8). Coordinates of Óbidos, indicative.
δ30Si in ‰ (per mil) Values of the same system
Standard : NBS 28
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 0.9 ‰ | 1 | Óbidos, 120 µM dissolved silicon, date not stated. | De La Rocha et al. (2000), A first look at the distribution of the stable isotopes of sil… | |
| 0.6 ‰ | 1 | 'Integrated' Amazon sample, location not stated: 0.3 ‰ off Óbidos. | De La Rocha et al. (2000), A first look at the distribution of the stable isotopes of sil… |
Deposits of the same type
- Amazon Brazil
- Rio Negro at Manaus Brazil
- Solimões at Manaus Brazil
- Tocantins Brazil
- Barro Alto ultramafic massif surface waters Brazil
- Paria River (PAR), geochemical background Bolivia
- Cala-Cala River (CC), geochemical background Bolivia
- Vinto River, station V1 Bolivia
Cite this page
IsoFind Atlas (2026). Amazon, lower course (Óbidos), isotope signatures. https://www.isofind.tech/isotopes/en/sites/amazone-cours-inferieur-obidos/ (accessed 2026-10-13).
@misc{isofind2026amazonlowercourseobidosisotop,
title = {Amazon, lower course (Óbidos), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/sites/amazone-cours-inferieur-obidos/},
note = {Accessed 2026-10-13}
}Updated : 2026-10-13