Gounkoto is characterised by sodic and phyllic alteration halos, As- and Fe-rich ore assemblages, and abundant magnetite.

Two hydrothermal fluids are identified: 1) a moderate T, dilute aqueo-carbonic fluid; 2) a high T, high salinity brine.

These two fluids mixed during ore formation, leading to enhanced phase separation and Au precipitation.

Fluid inclusion analysis indicates that ore formation occurred at P‐–T conditions of approximately 1.4 kbar and 340 °C.

Stable O, C and S isotopes suggest ore components were derived from metamorphic devolatilisation of sedimentary rocks.