The Bellevue gold deposit lies to the west of the Miranda shear, a dextral strike-slip shear with an eastern block-down component. It separates the Mt Goode sequence from the younger felsic volcaniclastics and ultra mafics and also appears to be a Riedel splay between the transpressional Keith-Kilkenny and the Ida Lineaments. The Project is located in an area of greenstone belt constriction, and associated structural complexities, with evidence of multi-scale shear zones and controlling faults coupled with a long and complex intrusion history. To the west, lie high-Ca granites and granitic gneiss. The major geological features in the Bellevue area are shown in Figure 3.
The surface geology of the Bellevue Project area is readily separated into two areas; subcrop to outcrop in the north and transported alluvium/colluvium in the south. The outcrop consists of Archean mafic lithologies in a range of low hills with thin residual soils that have a depth of weathering between 10 to 30 metres. Shallow Tertiary and Quaternary colluvium and alluvium can be found along the project area which sits immediately north of Lake Miranda to the south, as part of the paleo-drainage system. Lake Miranda is a playa lake system dominated by gypisferous dunes, lunettes and sandy, clayey, evaporitic lake floor deposits. Pleistocene red sand sheets and dunes form remnant deposits to a few metres thickness on the lower, western flanks of the hills. This sand/silt material has been reworked into the lake floor deposits with the evaporites.
The main Bellevue lode can be traced at surface along a strike length of over 1,500 metres. The hosting shear zone strikes north-south and dips from 45° to 85° west. Further gold mineralisation occurs in hanging wall and footwall structures both sub-parallel to the Bellevue Lode and in conjugate low angle mineralised shears. The Archean geology around the mine is dominated by Mt Goode sequence, a suite of tholeiitic mafic basalts and dolerites which range in grain size from fine to coarse. Pillow and flow-top breccias have often been recognized by geologists. Minor basalt with megacrystic plagioclase has been mapped locally, with minor sediments and felsic intrusives (felsic porphyry and granite dykes). The tholeiites strike north to north-east and dip steeply to the west and north west. Stratigraphy at Bellevue is overturned, and the direction of younging is to the south east.
Metamorphic grade of the area is upper greenschist to amphibolite grade however the strain distribution is heterogeneous with mylonites (greenschist-amphibolite facies metamorphism) developed within shear zones bounded by relatively undeformed tholeiites (greenschist facies metamorphism).