Iron Ore Prospecting in the Palaeoproterozoic Earaheedy Basin

Giralia Resources NL is targeting iron ore in the Miss Fairbairn Hills, Earaheedy Basin, Australia. Having conducted some preliminary fieldwork, and acquired high-resolution aeromagnetic data, Giralia commissioned SRK to produce a report on potential structural controls of iron ore deposits, and a series of 1:100,000 structural maps.

The Miss Fairbairn Hills is located on the northern margin of the Earaheedy Basin, 200km south of Newman and 1,000km NE of Perth.

The present day exposure of the Earaheedy Basin covers an area of about 30,000km2; however, evidence is present to show that the Basin was once much larger than current exposure, extending farther SW where erosional remnants still occur, and north where it is concealed by the overlying Collier (Bangemall) and Officer Basins. The basin fill is a 5km thick, coastal to near shore sedimentary succession, known as the Earaheedy Group, and is interpreted to have accumulated at a passive continental margin along the northeast edge of the Yilgarn Craton.

The Miss Fairbairn Hills region, located on the north side of the Basin, is thought to be the second largest accumulation of iron formations in Australia and is reported to contain a total of over 500 strike km of iron formations, up to 500m thick, in the Frere Formation of the Earaheedy Group. Previous exploration in the late 1970s resulted in locating widespread areas of hematite enrichment with surface grades up to 66% Fe (see the photo above). This includes zones, reported by Amax Iron in the 1970s to be up to 75m (true thickness) grading to 62% Fe. Giralia’s tenements cover 130 strike km of the most prospective areas defined by past exploration, including the Miss Fairbairn Hills (covering an area of 5,070km2).

Beds of the Frere Formation are mostly shallow dipping, providing the opportunity for mining large tonnages of resources. Giralia’s exploration target in the Miss Fairbairn Hills is very large, comprising > 1 billion tonnes within their tenements.

After SRK conducted an extensive structural and geological review of previous exploration, including Giralia’s own findings, high resolution aeromagnetic grid, and other datasets, Giralia are now using these results to help focus the targeting of outcropping zones of massive hematite. Prior to drilling, the next phase is likely to result in further fieldwork to verify the ground truth potential of identified targets.

Mike Cunningham: mcunningham@srk.com.au

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