# Metals speciation in (magmatic)-hydrothermal fluids from in-situ Raman spectroscopy

Marion Louvel, Tom Chatelin, Nicole Hurtig, Giada Iacono-Marziano, Aneta Slodczyk

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Marion Louvel, Tom Chatelin, Nicole Hurtig, Giada Iacono-Marziano, Aneta Slodczyk. Metals speci-ation in (magmatic)-hydrothermal fluids from in-situ Raman spectroscopy. 19th International Sym-posium on Experimental Mineralogy, Petrology and Geochemistry (EMPG 2025), Jun 2025, Orléans, France. . hal-05202914

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Submitted on 7 Aug 2025

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Distributed under a Creative Commons Attribution 4.0 International License
# Metals speciation in (magmatic)-hydrothermal fluids from in-situ Raman spectroscopy

MARION LOUVEL¹, TOM CHATELIN¹, NICOLE HURTIG², GIADA IACONO-MARZIANO¹ AND ANETA SLODCZYK¹

1 ISTO - CNRS-UMR7327 - Orleans, France - 2 New Mexico Tech - Socorro, NM, USA

CONTACT : marion.louvel@cnrs.fr

Institut des Sciences de la Terre d'Orléans
ISTO

Université d'ORLEANS

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Géosciences pour une Terre durable

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## METALS SPECIATION IN FLUIDS: STATE OF THE ART

### An increasingly detailed understanding

Complexes described at T > 250 °C (adapted from Brugger et al., 2016 [1])

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⇒ Many hydrothermal complexes have already been described.

⇒ BUT mostly under (very) acidic conditions and at T < 400 °C or extreme P.

### Solubility/partitioning Vs. Spectroscopic studies

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Tagirov and Seward, 2010 [2]

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⇒ In-situ laboratory approaches are needed to upscale the identification of metallic species under supercritical conditions

## IN-SITU RAMAN @ISTO

### The T-IHPV

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⇒ Up to 900 °C (±10) and 1500 bars (±1)

⇒ Transparent (sapphire) windows and sample cell

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### Raman set-up

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## OBSERVATIONS

### Identification of new metallic species

**Example 1: W-S complexes in low-density fluids**

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⇒ W previously reported as tungstates ($H_2WO_4$, $HWO_4^-$, $WO_4^{2-}$) in $H_2O/HCl/NaCl$ [4,5,6]

⇒ New complexes enable enhanced W solubility compared to $H_2O/Cl$ fluids (no $WO_3$ precipitation).

⇒ Suspected $WO_xS_y^2-$, also recently evidenced by XAS [7]

### Solubility behaviour to extreme T

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### Towards quantification ?

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**Aim**: Quantify Cl contents in vapor+brine after phase separation

**Approach**: Calibrate OH band area from the analysis of multiple (Na,K,Li)Cl solutions (0.005m-5m)

**Example 2: Te species in coexisting brine and vapor**

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⇒ Tellurates ($H_2TeO_3^0$, $HTeO_3^-$, $TeO_3^{2-}$) found stable to 500 °C in alkaline (ph 10) solutions.

⇒ Under acidic conditions different Te chlorides are found in brine ($TeCl_xTe^{y-}$) and vapor ($TeCl_4^0$).

## RÉFÉRENCES

[1] Brugger et al., 2016. Chem. Geol. 447, 219-253. [2] Tagirov and Seward, 2010. Chem. Geol. 269, 301-311. [3] Pokrovski et al., 2022. Am. Min. 107, 369-376. [4] Wood and Samson, 2000. Econ. Geol. 95, 143-182. [5] Carocci et al., 2022. GCA 317, 306-324. [6] Borchert et al., 2025. Eur. J. Mineral. 37, 111-130. [7] Mei et al., 2024. GCA, in press.

## FUNDING

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METGAS

PLANEX

## OUR TEAM

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