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Curnamona Province

The Curnamona Province is a 300km by 300km block of shallow to outcropping basement rocks that extends from Olary, in the northeast of South Australia, 450 kilometres north east of Adelaide, to east of Broken Hill across the New South Wales border.

Age

  • Sedimentation — late Palaeoproterozoic to early Mesoproterozoic.
  • Felsic and mafic volcanism — late Palaeoproterozoic to early Mesoproterozoic.
  • Granitic intrusion — late Palaeoproterozoic to early Mesoproterozoic, Cambro-Ordovician.
  • Olarian Orogeny — late Palaeoproterozoic(?) to early Mesoproterozoic.
  • Delamerian Orogeny — middle Cambrian to early Ordovician.

Prospective commodities

Cu, Au, Zn, Pb, Ag, U, REE, barite, wollastonite, feldspar, beryl, garnet and fluorite.

Major exploration models

  • Iron oxide–Cu–Au deposits
  • Broken Hill type Pb–Zn–Ag deposits
  • Stratiform, shale-hosted Zn–Pb–Ag (Mount Isa – McArthur Basin style) deposits
  • Vein gold
  • Sedimentary uranium (in Cainozoic sedimentary cover).

Curnamona Province Subdivisions

  • The Broken Hill Domain
  • The Olary Domain
  • The Weekeroo Inlier
  • The Mt Painter Inlier
  • The Mt Babbage Inlier
  • The Benagerie Ridge

The following maps show the major subdivisions listed above. 

Summary Geology

The Curnamona Province extends from Olary, in the northeast of South Australia, 450 kilometres north east of Adelaide, to east of Broken Hill across the New South Wales border. To the north it extends under cover, north of Lake Frome but can be identified on aeromagnetic maps by its distinctive magnetic signature. It consists of multiply deformed sediments, volcanics and granites ranging in ages from the Palaeoproterozoic to the Mesoproterozoic and referred to collectively as the Willyama Complex.

Subtle differences in metamorphic grade and deformation history have led to the subdivision between the Olary Domain in South Australia to the west, and the Broken Hill Domain in NSW to the east. Outcropping Willyama Supergroup rocks also appear as inliers in the Neoproterozoic cover at Weekeroo in the southwest and Mt Babbage and Mt Painter in the northwest.

Elsewhere, these rocks occur under a cover of younger sediments that range in age from Neoproterozoic, through Cambrian to those of Tertiary age and younger. The Benagerie Ridge is a major basement feature, comprising post deformation volcanics and sediments, that form a local topographic high separating Cambrian aged sediments of the Yalkalpo and Moorowie sub-basins.

During the Tertiary, an extensive network of rivers transported sediments from the higher, outcropping parts of the province, principally Olary Domain but also from the Mounts Babbage and Painter Inliers, out across the Benagerie Ridge.

With much of the Curnamona Province rocks occurring under cover, geophysical methods, measuring the properties of the rocks at depth, are an important tool for interpreting underlying geology and isolating potential targets. PIRSA holds world class aeromagnetic, detailed gravity and radiometric data over the Curnamona Province.

From a metallogenic point of view, the Curnamona Province is of great importance. It is host to the Broken Hill silver-lead-zinc mine and may host other similar bodies. In addition, the similarities in the deformation and alteration styles of the mineralised Moonta-Wallaroo portion of the Gawler Craton, the mineralised Mount Isa Block and the Curnamona Province all auger well for major copper-gold discoveries in the area.

Copper-gold prospects at Portia, White Dam and Kalkaroo are examples of what may be expected in the future. The Tertiary channel sediments host uranium mineralisation sourced from outcropping Curnamona Province rocks. These have formed economic accumulations at the Beverley and Honeymoon prospects.

More on the Geology of the Curnamona Province.