El Salvador (Indio Muerto)
Atacama, El Salvador district, Chile
PorphyriesCu (Mo)
- Type
- Cu-Mo porphyry
Copper porphyry of the Indio Muerto area: 43 to 41 Ma granodiorite porphyry complex (X, K and L porphyries) intruding Eocene rhyolite porphyries (about 44 Ma), Palaeocene rhyolites and Cretaceous andesites; mine developed on the Turquoise Gulch centre. At surface (276 samples, 2900 to 3300 m elevation), concentric zoning around the late granodiorite porphyry: muscovite-andalusite (up to 500 m), muscovite (500 to 1500 m), propylitic; retrograde pyrophyllite above 3000 m; radial hydrothermal breccia dykes with alunite, APS minerals, diaspore, zunyite, pyrophyllite and dickite, extending into a 300 × 500 m quartz-alunite outcrop. Muscovite fluid at δ18O +6.5 ± 1.5 ‰ and δD -40 ± 10 ‰ (about +8 and -35 ‰ in the andalusite zone, close to a magmatic fluid, less than 10 to 20 % meteoric water elsewhere); late alunite fluid from +5 and -30 ‰ to -1 and -40 ‰, magmatic vapour absorbed by local groundwater similar to that of supergene kaolinite, according to Watanabe and Hedenquist (2001). Indicative coordinates.
δ18O in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 8.94 ± 0.97 ‰ | 7.9 / 10.3 ‰ | 7 | muscovite of the andalusite-muscovite-diaspore assemblage (transitional to late stage) Mean and standard deviation recalculated from 7 analyses, fluid calculated at +6.0 to +8.4 ‰ at 375 °C, the closest to a magmatic fluid. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 8.29 ± 1.04 ‰ | 6.5 / 11.6 ‰ | 27 | muscovite of the muscovite zone and samples without an assigned assemblage Mean and standard deviation recalculated from 27 analyses, muscovite alone or with diaspore or pyrophyllite; fluid +4.7 to +6.6 ‰ (250 to 325 °C), less than 10 to 20 % meteoric water. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 8.37 ± 0.47 ‰ | 8 / 8.9 ‰ | 3 | muscovite-pyrophyllite mixtures (116, 207, 209) Mean and standard deviation recalculated from 3 analyses. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 7.7 ± 1.41 ‰ | 6.7 / 8.7 ‰ | 2 | retrograde and breccia-dyke pyrophyllite (5821, 6573) Mean and standard deviation recalculated from 2 analyses, 6573 analysed by Sheppard and Gustafson (1976); pyrophyllite after andalusite (5875) at +11.8 ‰ not included. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 9.65 ± 2.62 ‰ | 7.8 / 11.5 ‰ | 2 | late dickite (135, 212) Mean and standard deviation recalculated from 2 analyses, fluid -0.9 and -1.6 ‰ (150 and 100 °C). | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 10.14 ± 1.99 ‰ | 6.4 / 12.1 ‰ | 12 | hypogene alunite of breccia dykes and the lithocap Mean and standard deviation recalculated from 12 analyses, early and late alunite of 211 counted separately; fluid -1.3 to +5.4 ‰ (200 to 300 °C). | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 13.61 ± 1.91 ‰ | 10.4 / 15.8 ‰ | 7 | supergene kaolinite (surface and drill holes) Mean and standard deviation recalculated from 7 analyses, water calculated at -11.9 to -6.5 ‰ (25 to 35 °C), local meteoric water. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
δD in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −63.14 ± 3.72 ‰ | −70 / −59 ‰ | 7 | muscovite of the andalusite-muscovite-diaspore assemblage (transitional to late stage) Mean and standard deviation recalculated from 7 analyses, fluid -45 to -34 ‰. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −65.68 ± 6.14 ‰ | −79 / −55 ‰ | 17 | muscovite of the muscovite zone and samples without an assigned assemblage Mean and standard deviation recalculated from 17 analyses, fluid -53 to -30 ‰. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −61 ± 14.14 ‰ | −71 / −51 ‰ | 2 | retrograde and breccia-dyke pyrophyllite (5821, 6573) Mean and standard deviation recalculated from 2 analyses. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −74 ± 5.66 ‰ | −78 / −70 ‰ | 2 | late dickite (135, 212) Mean and standard deviation recalculated from 2 analyses. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −44.33 ± 4.52 ‰ | −55 / −38 ‰ | 12 | hypogene alunite of breccia dykes and the lithocap Mean and standard deviation recalculated from 12 analyses, fluid -45 to -32 ‰. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −90 ± 6.2 ‰ | −99 / −83 ‰ | 6 | supergene kaolinite (surface and drill holes) Mean and standard deviation recalculated from 6 analyses, water -68 to -52 ‰. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
δ34S in ‰ (per mil) Values of the same system
Standard : V-CDT
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 15.51 ± 2.41 ‰ | 9.6 / 18.8 ‰ | 15 | hypogene alunite of breccia dykes and the lithocap Mean and standard deviation recalculated from 15 analyses, NaOH values where available, otherwise KIBA; sulphur isotope temperatures higher than assemblage temperatures, possibly through partial supergene replacement. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| 12.1 ‰ | 1 | barite (208) Single analysis. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… | |
| −1.33 ± 2.65 ‰ | −4.7 / 1.4 ‰ | 4 | supergene alunite (138, 197, 3183, 130b) Mean and standard deviation recalculated from 4 analyses, sulphur from sulphide oxidation. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −4.2 ± 1.41 ‰ | −5.2 / −3.2 ‰ | 2 | pyrite of supergene alunite samples (197, 3183) Mean and standard deviation recalculated from 2 analyses. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
| −2.1 ‰ | 1 | supergene jarosite (213b) Single analysis; δ18O +5.4 ‰ and δD -96 ‰. | Watanabe et Hedenquist (2001), Mineralogic and Stable Isotope Zonation at the Surface ove… |
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Cite this page
IsoFind Atlas (2026). El Salvador (Indio Muerto), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/el-salvador-indio-muerto/ (accessed 2026-10-15).
@misc{isofind2026elsalvadorindiomuertoisotopes,
title = {El Salvador (Indio Muerto), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/el-salvador-indio-muerto/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15