Los Colorados
Atacama, Chilean iron belt, Atacama fault system, Chile
IOCGFe
- Type
- Iron oxide-apatite (Kiruna type)
Active iron mine 35 km north of Vallenar, 350 Mt Fe in two subvertical bodies with over 90 % magnetite (west body at 63 % Fe, east body at 55 % Fe), about 1500 m long, 150 m wide and 500 m deep, hosted by diorite and andesite of the Punta del Cobre Formation (Cretaceous), with no sodic or potassic alteration. Magnetite δ56Fe and δ18O within the range of igneous magnetite, intergrown actinolite in equilibrium at a minimum of about 630 °C (actinolite-magnetite pair) and 610 to 820 °C from its Fe#; mantle-like δD of actinolite (-59.3 ‰) and magnetite (-53.5 ‰); calculated parent magma at +6.6 ‰ and magmatic water at +7.1 ‰: high-temperature magmatic or magmatic-hydrothermal origin according to Bilenker et al. (2016). Indicative coordinates, derived from the distance to Vallenar.
δ56Fe in ‰ (per mil) Values of the same system
Standard : IRMM-014
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 0.17 ± 0.05 ‰ | 0.08 / 0.24 ‰ | 14 | massive magnetite of the west ore body (drill cores LC-04 and LC-05) Mean and standard deviation recalculated from 14 analyses, 05-129.3a and b averaged; the text quotes 0.18 to 0.26 ‰ (n = 8) for LC-04 and n = 9 for LC-05, which does not match the table; homogeneous along the whole drill cores. | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … |
| 0.18 ± 0.03 ‰ | 1 | massive magnetite of the east ore body (pitE1) Single analysis; 2σ uncertainty; the text gives +0.24 ± 0.02 ‰ for the east body. | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … |
δ18O in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 2.6 ± 0.37 ‰ | 1.92 / 3.17 ‰ | 13 | massive magnetite of the west ore body (drill cores LC-04 and LC-05) Mean and standard deviation recalculated from 13 analyses, the text gives +2.32 ± 0.12 ‰ (n = 7) for LC-04 and +2.76 ± 0.12 ‰ (n = 11) for LC-05, larger counts than the table; mean of +2.60 ± 0.74 ‰ used for the parent magma. | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … |
| 6.46 ± 0.4 ‰ | 6.18 / 6.74 ‰ | 2 | actinolite intergrown with magnetite (05-72.9) Mean and standard deviation recalculated from 2 analyses, the text uses +6.46 ± 0.56 ‰ and an actinolite-magnetite offset of 4.10 ‰, i.e. at least 630 °C (A factor = 3.36). | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … |
δD in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −59.3 ± 1.7 ‰ | 1 | actinolite Single analysis; 2.08 ± 0.04 wt% water; sign checked on the image. | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … | |
| −53.5 ± 1.5 ‰ | 1 | magnetite (structural water) Single analysis; only 0.10 ± 0.07 wt% water. | Bilenker et al. (2016), Fe–O stable isotope pairs elucidate a high-temperature origin of … |
Deposits of the same type
Cite this page
IsoFind Atlas (2026). Los Colorados, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/los-colorados/ (accessed 2026-10-15).
@misc{isofind2026loscoloradosisotopesignatures,
title = {Los Colorados, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/los-colorados/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15