Abstract
A temporal framework for mineral deposits is essential when addressing the history of their formation and conceptualizing genetic models of their origin. This knowledge is critical to understand how crust-forming processes are related to metal accumulations at specific time and conditions of Earth evolution. To this end, high-precision absolute geochronology utilising the rhenium-osmium (Re-Os) radiometric system in specific sulphide minerals is becoming a method of choice. Here, we present a procedure to obtain mineral separates of individual sulphide species that may coexist within specific mineralized horizons in ore deposits. This protocol is based on preliminary petrographic and paragenetic investigations of sulphide and gangue minerals using reflected and transmitted light microscopy. Our approach emphasizes the key role of a stepwise use of a Frantz isodynamic separator to produce mineral separates of individual sulphide species that are subsequently processed for Re-Os and sulphur isotope geochemistry.•Detailed method and its graphical illustration modified from an original procedure introduced by Saintilan et al. (2017, 2018).•Quality control and validation of monophasic mineral separates made by microscopic investigations and qualitative analysis of aliquots embedded in epoxy mounts.•The present method, which contributed to the successful results presented in the co-publication by Saintilan et al. (2020), demonstrates why other studies reporting Re-Os isotope data for mixtures of sulphide minerals should be considered with caution.
Highlights
Quality control and validation of monophasic mineral separates made by microscopic investigations and qualitative analysis of aliquots embedded in epoxy mounts
The present method, which contributed to the successful results presented in the co-publication by Saintilan et al (2020), demonstrates why other studies reporting Re-Os isotope data for mixtures of sulphide minerals should be considered with caution
Polished thin sections of the arsenopyrite-pyrite-mineralised samples were studied using transmitted and reflected light microscopy in order to establish the paragenetic relationships and constrain the workflow (Fig. 1) for optimum mineral separation of individual sulphides through modification of the protocol presented by Saintilan et al (2017, 2018)
Summary
Quality control and validation of monophasic mineral separates made by microscopic investigations and qualitative analysis of aliquots embedded in epoxy mounts. The present method, which contributed to the successful results presented in the co-publication by Saintilan et al (2020), demonstrates why other studies reporting Re-Os isotope data for mixtures of sulphide minerals should be considered with caution. Method name: Monophasic sulphide mineral separates Keywords: Re-Os-S isotope geochemistry, Sulphide, Mineral separates, Frantz isodynamic separator Article history: Received 26 March 2020; Accepted 20 May 2020; Available online xxx
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