Evidence for a Proterozoic carbonatite system in the Mount Isa Province, Australia

• Carbonatite system identified in the Proterozoic Mt Isa Province. • Cryptic appearance requires field observations, geochemistry, isotopes. • Coincided with regional hydrothermal alteration at ca. 1650 Ma. • Further evidence of mantle mass and energy flux in Mt Isa Region. Carbonatites are indicators of mantle processes, and they are economically important because of their association with rare earth element (REE), niobium and base metal deposits. Carbonatites and their associated lithologies (i.e. the carbonatite system) have not previously been identified in eastern Australia. We describe veins of dolomite calcite carbonatite, fenites and antiskarn, glimmerite, and alkali pegmatite from the Tommy Creek Domain, of the Eastern Subprovince of the Mount Isa Province (NW Queensland), that constitute a carbonatite system. The system can be identified from field relationships, geochronology, zircon trace elements, and stable and radiogenic isotopes. The emplacement of the carbonatite system coincided temporarily and spatially with regional hydrothermal alteration at ca. 1650 Ma in the Eastern Subprovince, which also has mantle isotopic affinities and is located above the boundary between thin and thick continental lithosphere.