Ti - V magnetite stratigraphy of the Upper Zone of the Windimurra Igneous Complex, Western Australia

Layered mafic intrusions (LMI) are stratified igneous bodies, with many examples that are economically significant for a number of metals including chromium, platinum group elements, vanadium, titanium, and iron. The Windimurra Igneous Complex (WIC) of the central Murchison Domain, Western Australia, the largest layered mafic intrusion in Australia, comprises a giant (2500 km(2)) LMI, with an interpreted thickness of approximately 11 km. The Upper Zone is free of primary hydrous minerals and contains ore-grade Fe-enrichment discoveries up to 66.6 wt% FeOt. Elevated Ti, V and Cr in magnetite at the base of the Upper Zone, and high Cr in the Middle Zone, combined with structural observations in the field, are consistent with injection of two separate magmatic pulses. In this study, four deep diamond drill cores and 92 reverse circulation drill holes from the Upper Zone and uppermost Middle Zone of the WIC sample a near continuous section of 820 m in the Upper Zone, including numerous magnetite-rich horizons. An increase in the whole-rock TiO2/V2O5 upward in the Upper Zone, a decrease in the frequency of magnetite-rich horizons, and an increase upwards in P content, have been used in combination with airborne magnetic surveys, to develop a magnetic stratigraphy for the Upper Zone. The stratigraphy reflects the prospectivity for magnetite, vanadium and chromium, all of which are more abundant at or near the base of the Upper Zone. Such exploration vectors can be used to better target local iron, vanadium as well as chromium mineralization, much of which appear spatially associated with the Upper Zone's basal contact.

Automated summary

Layered mafic intrusions have economic significance for metals like chromium and iron, with the Windimurra Igneous Complex in Western Australia being the largest in Australia. The Upper Zone of the complex is rich in iron and other minerals, making it a promising target for exploration.