The southern sector of Indiana’s Central Gawler Project covers the HGD, a late Archean-Proterozoic arcuate tectonostratigraphic terrane positioned in the heart of the Gawler Craton. Within Indiana’s jurisdiction, it encompasses three distinct greenstone belts: the Mullina Well, Hopeful Hill, and Lake Harris Greenstone Belts. Bounded to the south by the Yerda Shear Zone and marked by a lithological boundary to the north with the Wilgena Domain, the HGD features greenstone belt rocks with limited exposure. These rocks manifest as scattered hills of basalt, occasional outcrops of metasediment, and metakomatiite.

Indiana estimates that over 95% of the Lake Harris Greenstone Belt is concealed. The outcrop of highly weathered metakomatiite is confined to the northeast corner of Lake Harris, with greenstone basalts displaying relict pillow structures exposed at Hopeful Hill. The potential greenstone sequence lies beneath thin (<50m) Quaternary sand and Eocene fluvial channel deposits. Due to limited exposure, the distribution and structure of the greenstones rely heavily on the interpretation of aeromagnetics, gravity data, and diamond drill core analyses.

The HGD is characterized by a series of sub-parallel east-northeast trending sinuous magnetic high features, flanked by large ovoid to elongate magnetic highs and lows. Positioned within a geologically similar context to greenstones found in the Eastern Goldfields and Southern Cross Provinces of Western Australia, the HGD has the potential for hosting gold and base metals, a feature well-known in Western Australia’s Archaean greenstone belts.

Despite the recognized nickel sulphide potential attributed to hosting various belts of komatiite rocks of Archean (possibly earliest Paleoproterozoic) age, there has been limited exploration focus on these greenstone belts in South Australia to date. Notably, the Lake Harris Komatiite, discovered in 1991, marked the first documented occurrence of komatiite outside the WA craton and the easternmost presence of such primitive ultramafic rocks in Australia. Indiana holds a strategic advantage in having secured a substantial portion of the three primary known greenstone belts in the HGD: the Mullina Well, Hopeful Hill, and Lake Harris Greenstone Belts.