Metal mobility during hydrothermal breakdown of Fe-Ti oxides : insights from Sb-Au mineralizing event (Variscan Armorican Massif, France)

Authors: Pochon, Anthony; Beaudoin, Georges; Branquet, Yannick; Boulvais, Philippe; Gloaguen, Éric; Gapais, D.
Abstract: Hydrothermal alteration related to Sb-Au mineralization is widespread in the Variscan Armorican Massif, but mineral replacement reactions are not well characterized, in particular the hydrothermal breakdown of ilmenite-titanohematite. Based on petrography, electron probe micro-analyzer and laser ablation-inductively coupled plasma-mass spectrometer analyses, we document mineralogical change at rock- and mineral-scale and the redistribution of Sb and others trace elements during the recrystallization of ilmenite-titanohematite to hydrothermal rutile. Hydrothermal alteration is mainly potassic with associated carbonation. The replacement mechanism is interpreted to be an interface-coupled dissolution-reprecipitation process. Results show that Mn, Zn, Co, Ni, Sn, Mo and U are released during hydrothermal alteration, whereas Sb and W are incorporated in newly-formed hydrothermal rutile from the hydrothermal fluid. Furthermore, the concentration of Sb evolves through time suggesting a change in fluid composition likely related to an enrichment of fluid in Sb during rutile crystallization. Considering that Fe-Ti oxides breakdown during hydrothermal alteration is common within epithermal and mesothermal/orogenic Au-Sb mineralizing systems, results report in this study yield important constraints about metal mobility and exchanges in hydrothermal gold systems.
Document Type: Article de recherche
Issue Date: 24 October 2017
Open Access Date: 24 October 2019
Document version: AM
This document was published in: Ore geology reviews, Vol. 91, 66-99 (2017)
Alternative version: 10.1016/j.oregeorev.2017.10.021
Collection:Articles publiés dans des revues avec comité de lecture

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