Zircon and apatite as potential indicator minerals for mineral exploration

The analysis of indicator minerals, such as apatite and zircon, is a useful method in mineral exploration for assessing the prosperity of a host rock. Previous studies have demonstrated the usefulness of apatite trace element signatures for identifying mineralisation-related granitoids in the Mount Isa Inlier of northwestern Queensland, a region well-known for its Pb-Zn-Ag, Cu, and Cu- Au deposits. Extending on previous work, this study investigates both zircons and apatites from the same Mt Isa rock suites and uses trace-element signatures, U-Pb, Sr, and Hf isotopes to demonstrate the applicability of the zircon-apatite mineral pair for distinguishing mineralisation-related and mineralisation-absent granitoids. Geochronological studies reveal a ~1345 Ma hydrothermal event that is recorded in the apatite and is ~200 Ma years younger than the zircon U-Pb ages for the mineralisation-related granitoids. REE patterns and coupled-dissolution precipitation microstructures in the zircons are similarly suggestive of hydrothermal alteration of the granites. Comparison of the Hf, Sr, and Nd isotopic systems indicates an analogous magma source for the studied plutons, signifying that the mineralisation is most likely not related to the granitic magmatism, but rather associated with a later hydrothermal event.