Regional stratigraphic correlations and stratiform sediment-hosted base metal mineralisation in the northern Mt Isa Basin

The northern Mt Isa Basin contains two geographically separate Palaeoproterozoic to Mesoproterozoic lithostratigraphic successions: the Fickling Group north of the Elizabeth Creek Thrust Fault and the McNamara Group to the south. Both groups host base-metal mineralisation and correlation between the two suggests that mineralisation is not confined to a particular stratigraphic interval or single basin phase. Seismic stratigraphic analysis revealed many second and third order sequence boundaries that subdivide the stratigraphy. Onlap to the north accounts for the substantial difference in thickness between the two groups and means that many of the McNamara Group units have no correlatives in the Fickling Group. Contrary to the expectations of many people, lead-zinc mineralisation occurs in at least four stratigraphic levels contained within two basin phases. These occurrences of mineralisation are separated by thousands of metres of strata containing many sequence boundaries comprising major unconformities and their correlative conformities.