A new chronostratigraphic framework for the Mount Isa Inlier

Abstract

The integration of detrital and magmatic SHRIMP U-Pb zircon geochronology with facies analysis has allowed the development of a chronostratigraphic framework for the Leichhardt and Calvert Superbasins of the Western Fold Belt, Mount Isa Inlier. This new event chart recognises three supersequences in the Leichhardt Superbasin: the ~1800-1785 Ma Guide, ~1780-1765 Ma Myally and ~1755-1740 Ma Quilalar Supersequences. The younger Bigie Supersequence encompasses the Bigie Formation and is temporally associated with the ~1710 Ma Fiery magmatic event. This supersequence, together with the ~1690 Ma Prize Supersequence, comprise the Calvert Superbasin. Combining the new geochronological constraints with previous work now provides a detailed stratigraphic event framework between 1800 and 1575 Ma for the Western Fold Belt of the Mount Isa Inlier. Using this framework, it is now possible to develop detailed comparisons and correlations with the Eastern Fold Belt. This framework can then be used to generate facies models for the development of the Mount Isa region through time.