We adopt a systematic approach to creating the content of the Mineral Systems Atlas by applying the mineral systems concept of Wyborn et al. (1994) and McCuaig et al. (2010). This requires that we classify the different mineral system types, then analyse these systems to define the critical (necessary) metallogenic processes, and the potentially mappable geological features that might be expected to result from these.

Wyborn et al.(1994) defined a mineral system as ‘all geological factors that control the generation and preservation of mineral deposits’, but translating this concept into a generally accepted classification scheme for mineral systems has so far proved elusive.

However, knowledge of mineral deposit metallogeny has now advanced to the point of developing unifying models that permit classification of known deposit types or styles into genetically related families. One widely adopted approach is to classify mineral deposits based on their association with certain geological processes and mineralizing fluid types and sources (e.g. Lewis and Downes, 2008; Herrington, 2011). Six broad ‘Mineral System’ families (groups) of mineral deposit types may be recognized:

• Orthomagmatic
• Magmatic-related hydrothermal
• Deformation and metamorphism
• Basin-related fluid flow
• Sedimentary
• Weathering and regolith

The advantage of this scheme is that it is process oriented, implicitly recognizing that genetically related mineral occurrences should be associated in both time and space, and have common metal and fluid sources, and common ore mobilization, transport and deposition mechanisms. The constituent deposit classes and families are, therefore, amenable to mineral systems analyses to define the critical metallogenic processes. The scheme is also linked with conventional mineral deposit terminology and usage, and is compatible with the present typical focus by mineral explorers on a commodity or commodity group, and on particular mineral deposit type(s) that may contain such commodities.

The classification scheme may also be considered within a broader systems framework that includes geodynamic and tectonic setting (e.g. Fraser et al., 2007; Huston et al., 2016), but it does not require knowledge of these criteria; they are in any case non-unique for many deposit types and families, and may be indeterminate.

For a region to be prospective for mineral deposits now, it must necessarily show evidence for all the critical ingredients required for the formation and preservation of those deposits:

• source(s) of ore components, transporting fluids, and energy to drive the system (SOURCE)
• conduit(s) along which metals and fluids were transported from source to sink (PATHWAY)
• physical and/or chemical mechanism(s) that deposited ore components at the sink (TRAP)
• processes permitting preservation of mineralization in the crust up to the present time (PRESERVATION)

If any are absent from a region, its mineral prospectivity will be low.

The specific content of the Mineral Systems Atlas (the map layers) is determined using mineral systems analyses of the different mineral deposit classes (’mineral sub-systems’), to define how their critical ingredients might be manifested in mappable geology (adopting the approach recommended by McCuaig et al., 2010. In practical terms, we identify:

• the constituent geological processes by which the critical ingredients operated
• the geological features — or targeting elements — by which each constituent process might have been manifested
• the mappable geological proxies that represent the targeting elements (there may be more than one for each)

The Mineral Systems Atlas is a collection of geological proxy layers, grouped by mineral deposit class (’subsystem’), and labelled according to their content and the critical ingredient(s) they reflect (SOURCE, PATHWAY, TRAP, PRESERVATION).

The geological proxies included are those that are deemed most robust as targeting elements and can be practicably produced from available GSWA statewide geoscience databases. They are created using structured queries that extract relevant data directly from primary GSWA geoscience data sources. No new data are acquired or created, although primary databases have commonly been reformatted (also using structured queries) to meet the particular internal requirements of the Atlas (these are the Primary Data Layers in the Atlas).

All ’geological proxy’ and ’primary data’ layer queries are dynamically linked to original primary databases, and are scheduled to automatically update the derived map layers whenever new data are added to the primary databases. Users may therefore be confident that the data layers portrayed in the Mineral Systems Atlas are always current.

The accompanying guide (this document) provides descriptions of current metallogenic models for each mineral ’subsystem’, the results of the mineral systems analyses to define the potentially mappable geological proxies, and the procedures used to generate these layers from the primary geoscience databases. Also included are query syntax, and data dictionaries listing the terms used in specific queries to identify particular geological features in GSWA databases, so that users may adapt and apply the data extraction methodology to their own working environment and proprietary data.

Fraser, GL, Huston, DL, Gibson, GM, Neumann, NL, Maidment, D, Kositcin, R, 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, 76p.

Herrington, R 2011, Chapter 3.1 – Geological features and genetic models of mineral deposits, in SME Mining Engineering Handbook, (3rd edition), edited by P Darling, Society for Mining, Metallurgy, and Exploration, p. 83–104.

Huston, DL, Mernagh, TP, Hagemann, SG, Doublier, MP, Fiorentini, M, Champion, DC, Jaques, AL, Czarnota, K, Cayley, R, Skirrow, R and Bastrakov, E 2016, Tectono-metallogenic systems – The place of mineral systems within tectonic evolution, with an emphasis on Australian examples: Ore Geology Reviews, v.76, p.168–210.

Lewis, P and Downes, PJ 2008, Mineral systems and processes in New South Wales: a project to enhance understanding and assist exploration: NSW Geological Survey Quarterly Notes, v.128, p.1–15.

McCuaig, TC, Beresford, S and Hronsky, J 2010, Translating the mineral systems approach into an effective exploration targeting system: Ore Geology Reviews, v. 38, p. 128–138.

Wyborn, LAI, Heinrich, CA and Jaques, AL 1994, Australian Proterozoic mineral systems: Essential ingredients and mappable criteria: Proceedings of the Australasian Institute of Mining and Metallurgy Annual Conference, Darwin, 5–9 August 1994, p.109–115.