Is the Mount Isa copper deposit the product of forced brine convection in the footwall of a major reverse fault?

Abstract

Geochemical and mass-balance constraints in conjunction with stable isotope data indicate that the copper deposit of Mount Isa (Australia) formed by mixing of a reduced sulfur-rich fluid from overlying Mount Isa Group metasedimentary rocks with a copper-rich oxidized fluid entering a brecciated contact zone from underlying metabasalts. We have performed numerical simulations to test whether the deposit may have formed by forced fluid convection driven by progressive displacement on the Mount Isa fault zone, indicated by an ∼200 °C offset in metamorphic grade. Results indicate that uplift of ≥ 1 mm/yr induces regional fluid flow organizing into a stable, permeability-controlled circulation sy..