Minerals on the Edge: Rethinking Sediment-Hosted Base Metals and Australia's Undercover Potential - A Geoscience Australia Publication
- Noel Ong
- Nov 16, 2025
- 9 min read
Updated: Dec 9, 2025
Reference: This Samso Insights is based on the research paper: "Minerals on the Edge: sediment-hosted base metal endowment above steps in lithospheric thickness" by Czarnota, K., Hoggard, M.J., Richards, F.D., Teh, M., Huston, D.L., Jaques, A.L. and Ghelichkhan, S., 2020. Minerals on the edge: sediment-hosted base metal endowment above steps in lithospheric thickness. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.
Introduction – The Undercover Frontier
As the global energy transition accelerates, demand for base metals like copper (Cu), lead (Pb), zinc (Zn), and nickel (Ni) is booming. Yet, exploration success rates for major discoveries are shrinking worldwide. In Australia—home to an array of world-class resources—the biggest challenge isn’t finding the right rocks, it’s working out where to start looking beneath the post-mineralisation cover that hides up to 80% of the continent’s prospective geology.
In this Samso Insights report, we break down a compelling new framework built by Geoscience Australia and collaborators from Harvard, ANU, and Imperial College London. Their research takes a step back—beyond ore systems and basin models—to investigate the deeper control of the lithosphere on sediment-hosted base metal deposits.
This Samso Insight aims to summarise the paper and share with readers the work that was done. This is published to share the work and not claim the content as an organic work by Samso.
The Search For Base Metals In Australia - The standout finding?
85% of the global sediment-hosted base metal endowment sits within 200 km of the edge of thick lithosphere—the lithosphere–asthenosphere boundary (LAB)—and this trend holds across all geological eras.
This is the first statistical global study to show that craton architecture is the strongest predictor of where the world’s giant sediment-hosted deposits occur—including Australia’s yet-undiscovered giants.
Mineral Potential Heat Map – Key Highlights
(Source: Czarnota et al. 2020)
85% of the world's sediment-hosted base metal deposits occur within 200 km of the edge of thick lithosphere (>170 km depth).
This includes all “giant” deposits of >10 Mt of metal, ranging from the Proterozoic to the Phanerozoic.
The lithosphere-edge statistical relationship remains robust across all deposit types—whether Pb-Zn clastic-dominated, Mississippi Valley-type, or sedimentary copper.
The research reveals a new mineral exploration strategy: target basins sitting over or adjacent to lithospheric steps, not just basin-scale stratigraphy or fault geometry.
Within Australia, this model reduces the total exploration area to ~15% of the continent, a globally significant frontier.
Estimated undiscovered metal endowment in Australia: ~50–200 Mt of contained metals—worth ~$1 trillion in today's terms.
Global Significance
(Figure 1 — Global clustering at the 170 km LAB edge)
This figure plots PbZn, Cu-sed, and MVT deposit locations globally. Bubble size scales with tonnage; colours denote deposit age. The dominant clustering along the 170 km lithosphere contour is obvious—and statistically unprecedented. The trend? It’s not tied to a particular basement, age, or sediment profile. It seems controlled by the deep thermochemical architecture of the continent.
Figure 1: Global clustering at the 170 km LAB edge. (Source: Czarnota et al., 2020)
Why the Lithosphere Matters – Rethinking System Architecture
Traditional exploration models focus on the sedimentary basin level—fluid sources, rocks, pathways, and traps. This study shows we need to think deeper and broader.
When a basin forms along a lithospheric step:
(Figure 2 — System schematic (E–O–I–R).)
Rifting is mechanically focused, producing thick sediment piles and long-active faults.
Subsidence is deeper and more prolonged, giving fluids time and pressure to move metals.
Basins remain cooler at depth, due to thicker cratonic roots—extending the thermal window for metal deposition.
Preservation potential increases as post-depositional tectonics are lower-energy near stable cratonic blocks.
This is how multiple tectonic systems over 2 billion years bred enduring mega-deposits like Mount Isa, Red Dog, or Kupferschiefer. It also explains why smaller, sub-giant deposits still show up elsewhere—but the biggest ones almost always live where the lithosphere was already behaving differently.
Figure 2: System schematic - Evaporites, Oxidised sediments, Igneous feeders, Reduction traps (E–O–I–R). (Source: Czarnota et al., 2020)
Australia’s Craton-Edge Advantage
(Figure 3a — Australia LAB map + deposits)
Figure 3a: Australia LAB map + deposits. (Source: Czarnota et al., 2020)
In the higher-resolution Australian model, all giant sediment-hosted and IOCG deposits lie within ~100 km of the 170 km LAB contour.
The Australian Discovery Potential – 2025+ and Beyond
What happens when you apply this lithosphere-edge filter to Australia?
~15% of the total landmass remains highly prospective for sediment-hosted metals after layering in geological proxies such as black shales, evaporites, oxidised sediments, and mafic volcanics.
Most of the ultra-prospective zones lie under cover—particularly in WA’s northeast, NT’s interior, and central QLD.
Using global averages of metal endowment per km of prospective lithospheric edge, Australia likely contains 50–200 Mt of undiscovered metal, with realistic prospects for multiple new world-class districts.
This redefines Australia’s frontier search space: not just in terms of traditional basin architecture, but lithospheric structure and long-term geodynamic stability.
Figure 3b visualises the mass-weighted clustering of global sediment-hosted base metal endowment relative to the 170 km LAB contour, mass-weighted for 109 PbZn-CD, 147 PbZn-MVT, and 139 Cu-sed deposits, plus the combined curve.
Figure 3b: Global CDF (mass-weighted). (Source: Czarnota et al., 2020)
Mineral Potential Heat Map
The map in Figure 3c — National mineral-potential heat map, overlays lithospheric depth contours with stacked sedimentary proxy layers from the Australian Stratigraphic Units Database. The result: a data-backed target corridor that narrows down >7.7 million km² to just ~1.1 million km² of the highest priority ground.
Figure 3c: National mineral-potential heat map. (Source: Czarnota et al., 2020)
Figure 3d — Model performance (CDF vs retained area) below. The performance check of the heat-map in Figure 3c. The solid line shows a mass-weighted CDF of Australia’s known sediment-hosted base metals versus mineral-potential score, while the dark-grey and light-grey curves show the percentage of Australia’s area retained at each cutoff (whole continent vs. the clipped “hot-zone” corridor). The key takeaway: the curve rises steeply for deposits while the area curves stay low—meaning the model captures most metal endowment while screening out most ground, enabling search-space reductions to roughly ~15% of the continent with strong retention of known resources.
Figure 3d: Model performance (CDF vs retained area). (Source: Czarnota et al., 2020)
Investor Lens — Questions to Ask Management
LAB proximity: How far is the ground from the lithosphere–asthenosphere boundary (LAB) 170 km contour? Do internal targets sit within ~100–200 km of the edge?
Stacked E–O–I–R evidence: What evidence do you have for Evaporites, Oxidised sediments, Igneous/mafic inputs, and Reduction traps (black shales)? Show sections, logs, or proxy datasets.
Passive seismic coverage: Has the area been covered by modern passive seismic / tomography? If so, how does the local LAB pick align with targets?
Tenure inside the corridor: What % of the company’s tenure falls inside the high-potential heat-map corridor (Fig. 3c), and how is the drill budget weighted towards it?
Samso Concluding Comments
When I saw this paper being posted on LinkedIn (My apologies for not noting who posted it initially), I felt that this would be a great Samso Insight. I have been a tragic believer and follower of mineral exploration concepts for a long time, and I hope this insight will help the non-geoscientists gain some insight into this wonderful industry.
The paper is all about gaining knowledge of another concept to create predictive clarity. By showing that the mass of global sediment-hosted endowment clusters near the 170 km LAB contour—and that Australia’s giants tighten to ~100 km—the study converts a geodynamic insight into a practical filter. That’s rare in exploration science, and it gives decision-makers something you can map, rank, and budget against.
The reason I wanted to bring this paper to the Samso platform is because this is the kind of thinking that will and should drive mineral exploration in 2025. There are countless examples of recent mineral deposit discoveries that sit in the realm of this form of innovative thinking over the last few decades. My favourite story would have to be the discovery of Olympic Dam, which, for me, was exactly the out-of-the-box (At that time) thinking that led Western Mining to discover what is a Giant discovery.
Coffee with Samso: The Olympic Dam Story: An Insight into the Mineral Exploration Genius of WMC Limited
For investors, the implication is straightforward: capital should chase this kind of research, not just historical concepts. Technology in 2025 is far superior, and concepts such as passive seismic, for example, are more likely to enjoy better discovery efficiency, especially under cover where line-of-sight geology fails.
The days of knocking over a gossan and then making a discovery are now few and far between drinks. Research concepts, such as what is talked about in the paper, are now backed by more sophistication, and it is all about de-risking as much as possible to conserve capital and to make this capital funding stretch longer.
For companies, this isn’t a substitute for geoscience fundamentals—it just means that mineral exploration thinking needs to = re-order the sequence. It is too simple to just think about the theory; one still has to do the basics and tick boxes: engage the lithosphere step; stack the mineral system ingredients; then deploy geophysics, geochem, and drilling where the vectors converge. Figure 3d’s performance curve shows that you can keep most of the known metal while cutting most of the ground. It has always been about understanding and executing a systematic path to lower metres per discovery.
My mineral exploration concept has been guided by the likes of Jon Hronsky to always look at the bigger narrative. Australia still has room for a new world-class province. The recent discovery of a large number of "new" giant/large mineral deposits is a testament to this kind of thinking. The recent discovery of the West Arunta carbonatites and hence the building of a Tier-1 carbonatite province is the result.
The estimate of 50–200 Mt undiscovered across frontier basins isn’t blue-sky—it’s a data-anchored extrapolation along craton edges. In the Samso playbook, that’s enough to justify disciplined, multi-year campaigns focused on edge corridors—because that’s where the science—and history—say the giants live.
The Samso Way – Seek the Research
This is the kind of grounded, system-scale research that helps investors and companies spot conceptual edges before they become industry trends. The next North Australian Zinc Belt? It’s probably already mapped—if we know where to look.
Reference:
This Samso Insights is based on the research paper: "Minerals on the Edge: sediment-hosted base metal endowment above steps in lithospheric thickness" by Czarnota et al., 2020. Published with permission of Geoscience Australia.
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