Mineral Deposits Mineral Systems and Mineralising Events

The Australian continent hosts many mineral commodities in a range of mineral deposit types distributed in all states and the Northern Territory. The distribution of Australia's mineral deposits is shown on the Australian Mines and Mineral Deposits. Maps and resource data of Australian mineral deposits and mineral occurrences are available through the Australian Mines Atlas, an on-line information and mapping system.

Mineral deposits are naturally occurring accumulations or concentrations of metals or minerals of sufficient size and concentration that might, under favourable circumstances, have economic value.  Economic concentrations of metals or other mineral commodities are known as ore. Mineral resources are naturally occurring concentrations of minerals that are potentially economic to extract. These are classified according to the degree of geological assurance and economic feasibility based on the McKelvey resource classification system and compiled in the national resource inventory described in Australia's Identified Mineral Resources.

The distribution of mineral deposits is determined by the geological processes that formed them. Mineral deposits are therefore commonly clustered in geological provinces (mineral provinces or mineral districts) with some provinces being strongly endowed in particular mineral commodities (Jaireth and Huston, 2010). An example is the Hamersley Basin in the Pilbara which hosts most of Australia's known iron ore deposits and resources. Maps showing the distribution of Australia's major deposits and endowment by region for the major commodities (coal, copper, gold, iron ore, minerals sands, nickel, phosphate rock, lead and zinc) are available at Minerals maps.

The distribution of mineral deposits is also determined by the timing of ore forming processes. Ore deposits have formed at various periods over geological time from at least 3500 million years ago to the present day where mineral deposits are forming as part of natural earth processes both on land and on the sea-floor. Deposits have commonly formed through a combination of geological factors closely related in time. Advances in the dating of geological processes have shown that many ore deposits formed over a relatively short time period associated with particular geological processes. These mineralising events punctuate geological time, many have been repeated throughout the geological record, and most can be related to tectonic events.

Mineral deposits have historically been classified according to a number of geological parameters including their geological setting, host rocks, or conceptual models of formation. The most widely adopted, especially for resource assessments, is the mineral deposit models classification of Cox and Singer (1992) published by the USGS, which includes grade and tonnage models. A modified version of these mineral deposit models for Australia's major mineral deposit types is available on the Australian Mines Atlas. Australia's mineral deposits are described in the AUSIMM monographs on the Geology and Mineral Deposits of Australia and Papua New Guinea. Solomon and Groves (1994, updated 2000) provide a comprehensive synthesis of the geology and origin of Australia's mineral deposits. A summary of the exploration models for major Australia mineral deposit types is published in the AGSO Journal of Geology and Geophysics, vol.17 no. 4.

The mineral systems approach to mineral deposit genesis, originally proposed by Wyborn et al (1994), attempts to provide a framework that considers all the geological processes that control the formation and preservation of mineral deposits. An overview of the major mineral systems of Australia is given by Jaques et al. (2002). The mineral systems approach was extended through the work of the Predictive Mineral Discovery Cooperative Research Centre to include five major questions that provide key information on the geodynamic and geological settings and other parameters associated with the genesis of the deposit. The mineral systems concept has been further extended by Fraser et al. (2007) and places the deposit models and types in a systems framework that includes geodynamic environment, tectonic setting, and fluid/magma involved in mineralisation. Geoscience Australia's Mineral Systems Section uses this approach to increase the understanding of Australia's mineral prospectivity, particularly for economically and strategically important minerals.

Table 1: Geodynamic and tectonic classification of mineral systems
Geodynamic environment Tectonic setting Mineral system group Deposit type Metal association Fluids and magma
Convergent-extensional Continental backarc Basin-related fluid flow, with active magmatism Carlin-type Au-Ag-As-Sb-Hg Meteroric magmatic-hydrothermal
BHT/Sullivan-type Zn-Pb-Ag Zn-Pb-Ag-Cu-Au Basinal brines
Kuroko-type VAMS Zn-Cu-Pb-Ag-Au Evolved seawater; magmatic-hydrothermal
Algoma-type BIF Fe Evolved seawater
Magmatic-related hydro thermal Intrusion-related Au Au-Ag-Sb-Cu-Pb-Zn-Sn-W-Mo-Bi-Te Magmatic-hydrothermal; metamorphic
Olympic Dam-type IOCG Fe-Cu-Au-Ag-U-REE-Co-Mo-P-Nb Magmatic-hydrothermal, meteoric
Cloncurry-type IOCG Fe-Cu-Au-Ag-As-Co-Mo-P Magmatic-hydrothermal, metamorphic
Convergent-extensional Island backarc Basin-related fluid flow, with active magmatism Kuroko-type VAMS Zn-Cu-Pb-Ag-Au Evolved seawater; magmatic-hyrdrothermal
Cyprus style VAMS Cu-Zn-Co-Ag-Au Evolved seawater; magmatic-hyrdrothermal
Algoma-type BIF Fe Evolved seawater
Ortho-magmatic Podiform chromite Cr Tholeiitic ultramafic magmas
Convergent-contractional Continental arc Magmatic-related hydro-thermal Porphyry Cu-Au-Ag-Mo Magmatic-hydrothermal
Epithermal (adularia-sericite) Au-Ag Meteoric; magmatic-hydrothermal
Epithermal (advanced argillic) Au-Cu-Ag Magmatic-hydrothermal
Skarn Fe-Cu-Zn-Pb-Sn-W-Mo Magmatic-hydrothermal
Candelaria style IOCG Fe-Cu-Au-Ag-U-As-Co-Mo-P-Nb-Ni-REE Magmatic-hydrothermal
Ortho-magmatic Intrusion-hosted Ni-Cu-PGE Ni-Cu-Pt-Pd-Au-Co Tholeiitic mafic magmas
Strata-bound Cr-PGE Cr-Pt-Pd Tholeiitic mafic-ultramafic magmas
Merensky Reef-type Ni-PGE Ni-Pt-Pd Tholeiitic mafic-ultramafic magmas
Podiform chromite Cr Tholeiitic ultramafic magmas
Convergent-contractional Island arc Magmatic-related hydro-thermal Porphyry Cu-Au-Ag-Mo Magmatic-hydrothermal
Epithermal (adularia-sericite) Au-Ag Meteoric; magmatic-hydrothermal
Epithermal (advanced argillic) Au-Cu-Ag Magmatic hydrothermal
Skarn Fe-Cu-Zn-Pb-Sn-W-Mo Magmatic hydrothermal
Forearc accretionary wedge Not known
Forearc basin Magmatic-related hydro-thermal Intrusion-related Au Au-Ag-Sb-Cu-Pb-Zn-Sn-W-Mo-Bi-Te Magmatic-hydrothermal; metamorphic
Weathering and regolith, physical concentration, reduced atmosphere Palaeo-placer Au-U Au-U-Pt-Pd Meteroric
Pro-foreland Not known
Retro-foreland Basin-related fluid flow, without active magmatism MVT style Pb-Ag-Zn Zn-Pb-Ag Basinal brines
Collisional Deformation and metamorphism Lode Au Au-Ag-As-Sb-Te-W-Bi Metamorphic; magmatic-hydrothermal
Mt Isa type Cu Cu Metamorphic
Cobar style Pb-Zn-Cu-Au Pb-Zn-Ag-Cu-Au Metamorphic
Tennant Creek-type IOCG Cu-Au-Bi-Se-Pb-Zn-U Magmatic-hydrothermal, basinal brines and metamorphic
Divergent Mid-oceanic ridge Basin-related fluid flow, with active magmatism Cyprus style VAMS Cu-Zn-Co-Ag-Au Evolved seawater; magmatic-hydrothermal
Ortho-magmatic Ophiolite hosted Cr, Ni Cr-Ni Mafic magmas
Continental rift Basin-related fluid flow, with active magmatism BHT/Sullivan-type Zn-Pb-Ag-Cu-Au Basinal brines
Ortho-magmatic Carbonatite-hosted REE REE-P-F-Mo-Cu-Pb-Zn Alkaline carbonatitic magmas
Diamonds Dia-mond Alkaline ultramafic magmas
REE and P-rich nepheline syenite REE-P-F Alkaline felsic magmas
Anorthosite-hosted Fe-Ti-V Fe-Ti-V Tholeiitic mafic magmas
Intrusion-hosted Ni-Cu-PGE Ni-Cu-Pt-Pd-Au-Co Tholeiitic mafic magmas
Komatiitic-hosted nickel sulphide Ni-Cu-Pt-Pd-Au Komatiitic mafic magmas
Rifted arc Basin-related fluid flow, with active magmatism Kuroko-type VAMS Zn-Cu-Pb-Ag-Au Evolved seawater; magmatic-hydrothermal
Algoma-type BIF Fe Evolved seawater
Magmatic-related hydro-thermal Epithermal (adularia-sericite) Au-Ag Meteoric; magmatic-hydrothermal
Hotspot Oceanic Basin-related fluid flow, with active magmatism Cyprus style VAMS Cu-Zn-Co-Ag-Au Evolved seawater; magmatic-hydrothermal
Continental Ortho-magmatic Flood-basalt associated Ni-Cu-PGE Ni-Cu-Pt-Pd-Au-Co Mafic magmas
Intraplate Ocean basin Sedimentary Mn-Ni-Co-nodules Mn-Ni-Co Oxidized seawater
Passive margin Sedimentary Hammersley-type BIF Fe Reduced seawater
Sedimentary manganese Mn-Ni-Co Reduced seawater
Sedimentary sulphate SO4-Ca-Ba Oxidized seawater
Sedimentary phosphate P Oxidized seawater
Basin-related fluid flow, without active magmatism Mt Isa-type Zn-Pb-Ag Zn-Pb-Ag Basinal brines
Distal contraction Basin-related fluid flow, without active magmatism MVT style Pb-Ag-Zn Zn-Pb-Ag Basinal brines
Irish-style Pb-Zn Zn-Pb-Ag Basinal brines
Sediment-hosted Cu-Co Cu-Co-Ag Basinal brines
Unconformity U U-P-REE-Cu-Au Basinal brines
Kipushi type Cu-Zn-Pb Cu-Zn-Pb ?
Laisval-type Pb Pb Basinal brines
Inactive continental Basin-related fluid flow, without active magmatism Rollfront-palaeo- channel U U-P-REE Basinal brines
Weathering and regolith, chemical concentration Lateritic Ni Ni-Au Meteoric
Lateritic bauxite Al Meteoric
Calcrete Au-U Au, U Meteoric
Supergene enrichment Au-Cu-Pb-Zn Meteoric
Placer Ti-Zr-Th-Hf Ti-Zr-Th-Hf Meteoric
Placer Au Au Meteoric
Placer Sn-Ta Sn-Ta Meteoric
Weathering and regolith, physical concentration Placer Ti-Zr-Th-Hf Ti-Zr-Th-Hf Meteoric
Placer Au Au Meteoric
Placer Sn-Ta Sn-Ta Meteoric
Variable Orthomagmatic Pegmatite Ta-Sn Felsic magmas
Strike-slip Pull-apart basin Basinal fluid flow Salton Sea-type Zn-Pb-Cu Zn-Pb-Cu Basinal brines
Pop-up Deformation and metamorphism Lode Au Au-Ag-As-Sb-Te-W-Bi Metamorphic; magmatic-hydrothermal

References

  1. Cox, DP and Singer, DA 1986. 'Mineral deposit models'. US Geological Survey Bulletin, 1693, 379  pp.
  2. Fraser, GL, Huston, DL, Gibson, GM, Neumann, NL, Maidment, D, Kositcin, N, Skirrow, RG, Jaireth, S, Lyons, P, Carson, C, Cutten, H and Lambeck, A 2007. 'Geodynamic and Metallogenic Evolution of  Proterozoic Australia from 1870 - 1550 Ma: a discussion'. Geoscience Australia Record 2007/16, 76 pp.
  3. Jaireth, S and Huston, D, 2010. 'Metal Endowment of Cratons, Terranes and Districts: Insights from a Quantitative Analysis of Regions with Giant and  Super-giant Deposits'. Ore Geology Reviews, 38, 288-303.
  4. Jaques, AL, Jaireth, S, Walshe, JL 2002. 'Mineral systems of Australia: an overview of resources, settings and processes'. Australian Journal of Earth Sciences, 49,  623-660.
  5. Solomon, M,and Groves, DI 2000. 'The Geology and Origin of Australia's Mineral Deposits. Centre for Ore Deposit Research and  Centre for Global Metallogeny', Pun. No. 32, 1002 pp.