Volcanic Metallogeny
How volcanism builds the world's ore deposits. Most of the metal we mine was concentrated by magmatic and hydrothermal processes tied to volcanism — and the tectonic setting of a volcano predicts which kind of deposit can form near it. This page explains those volcano→metal links in detail, and maps every Holocene volcano on Earth tagged by the deposit style its setting favours. It is geological context for exploration — not a hazard or eruption-risk product.
🌋 The volcano → metal connection
Each deposit family forms in a specific magmatic plumbing system. The metals, the depth, the host and the tell-tale alteration are all set by how and where the magma rises.
Porphyry Cu-Mo-Au
The planet's main copper source. Large, hydrous arc magmas stall as a pluton; as they cool, magmatic-hydrothermal fluids exsolve and deposit metals in dense stockwork veinlets over the cupola. Huge tonnage, low grade, concentric alteration (potassic → phyllic → argillic → propylitic).
Continental & oceanic subduction arcs.
Epithermal Au-Ag (HS / LS)
Shallow (<1.5 km) hot-spring systems above arc volcanism. High-sulfidation = acidic magmatic fluids → vuggy silica + alunite. Low-sulfidation = neutral, meteoric-dominated → adularia-sericite + banded quartz veins. Bonanza gold grades possible.
Subaerial felsic–intermediate arc volcanoes & calderas.
VMS — volcanogenic massive sulfide
Sulfides precipitated on or just below the seafloor at submarine volcanic centres — fossil "black smokers". Kuroko-type form in felsic island-arc/back-arc settings; Cyprus-type in ophiolitic (oceanic-crust) settings.
Submarine arcs, back-arcs & spreading ridges.
Skarn
Where an arc intrusion bakes and replaces carbonate wall-rock, building calc-silicate skarns charged with metal. Often flanks porphyry systems.
Arc intrusions cutting limestone/dolomite.
Alkaline complex / carbonatite
Deep, CO₂-rich alkaline magmas rising along continental rifts crystallise carbonatites and alkaline complexes — the world's premier source of rare-earth elements and niobium.
Continental rift / intraplate magmatism.
Greenstone-hosted & komatiite (ancient)
Archean–Proterozoic greenstone belts — ancient submarine volcanic piles — host the great orogenic gold camps (gold remobilised into shear-hosted quartz veins) and komatiite-hosted nickel. Not Holocene, so not on the live map — but it is the setting of much of GeaSpirit's second-chance gold (e.g. Marvel Loch), and where buried impact structures like Ora Banda can further focus metal.
Archean greenstone belts (Yilgarn, Abitibi, Barberton).
🗺️ World volcano map — tagged by deposit style
Every Holocene volcano (Smithsonian GVP), coloured by the ore-deposit style its tectonic setting favours. Click a volcano for its setting, rock type and metallogenic potential. Click a legend chip to filter.
Volcano data: Smithsonian Institution, Global Volcanism Program (GVP) — Holocene Volcano List (open data). Deposit-style tags are GeaSpirit's interpretation of tectonic setting and are indicative geological context, not a resource or discovery claim. Metallogenic models summarised from standard economic-geology literature.
📖 How to read this geological information
Every volcano, deposit and occurrence record shows the original scientific values and a plain-language interpretation. Scientific values are never changed; where a field is missing it reads “Not reported”.
Worked example — Cabezo María lamproite volcano▾
Scientific view
- Name / type
- Cabezo María — lamproite volcano, Almería, SE Spain
- Coordinates
- 37.2119, −1.9325
- Epoch
- Miocene
- Age
- ~8.6 ± 0.3 to ~7.9 Ma
- Stage (source label)
- Tortonian–Messinian
Plain-language view
- Name / type
- An ancient lamproite volcano (a rare, potassium-rich volcanic rock).
- Coordinates
- Latitude 37.2119°N, longitude 1.9325°W (negative longitude = west of Greenwich).
- Age
- Roughly 8.6 to 7.9 million years old. The “±0.3” is scientific uncertainty: 8.6 ± 0.3 Ma means most likely between about 8.3 and 8.9 million years.
- Stage
- Within the Miocene Epoch. The numeric dates shown (8.6–7.9 Ma) fall mainly in the Tortonian Stage under the current international timescale; the source's “Tortonian–Messinian” label describes a broader regional interval.
Field-by-field explainer▾
Why geological age matters▾
Age helps relate volcanic, tectonic, hydrothermal and mineral-forming events to one another — whether an eruption, an intrusion and an ore-forming fluid pulse could plausibly belong to the same system.
Age alone does not prove an economic deposit. Whether useful mineralisation exists depends on the wider context: tectonic setting, host rock, structure, hydrothermal alteration, the commodity in question, grade, tonnage, depth, and modern verification.
Understanding uncertainty (±)▾
Geological ages are estimates, not exact dates. Uncertainty comes from analytical precision, sample quality, alteration, the dating method, calibration and interpretation.
8.6 ± 0.3 Ma means a best estimate of 8.6 Ma with a margin of about ±0.3 — most likely between roughly 8.3 and 8.9 Ma. It is one age with a margin of error, not two separate ages.
Glossary — geological & metallogenic terms▾
🌍 Plate tectonics — the deep engine of metallogeny
Volcanism is the surface symptom; plate tectonics is the cause. The type of plate boundary sets the heat, fluids and structures available — and therefore which ore deposits can form. Below: how each boundary type builds (or fails to build) mineral systems, with real examples and citable sources. The 241 present-day boundaries are a live overlay on the main asset map — toggle 🌐 Tectonic Plates.
Convergent — subduction zones
An oceanic plate dives beneath another plate. Water driven off the slab fluxes the mantle wedge, generating hydrous, oxidised arc magmas — the single most productive metallogenic setting on Earth. These magmas feed porphyry Cu-Au-Mo systems, shallow epithermal Au-Ag, skarns and arc VMS.
Slab dehydration → flux melting → hydrous arc magmatism → magmatic-hydrothermal fluid release.
Convergent — continental collision (orogens)
When two continents collide the crust thickens, heats and melts. Metamorphic dewatering drives orogenic gold into shear-hosted quartz veins; crustal anatectic granites concentrate tin and tungsten; pegmatites carry Li-Ta.
Crustal thickening → regional metamorphism → metamorphic/anatectic fluids → vein & granite-hosted deposits.
Divergent — mid-ocean ridges & back-arcs
Plates pull apart; seawater convects through hot young crust and precipitates seafloor massive sulphides / VMS at black smokers. Where that oceanic crust is later obducted onto land (ophiolites), it also hosts podiform chromite.
Decompression melting → seawater hydrothermal convection → sulphide precipitation on/under the seafloor.
Divergent — continental rifts
A continent begins to split. Deep, CO₂-rich alkaline magmas rise along the rift and crystallise carbonatites and alkaline complexes — the world's premier source of rare earths and niobium. Rift basins and brines also concentrate lithium and sediment-hosted copper.
Lithospheric extension → low-degree alkaline/carbonatite melting → REE-Nb enrichment; evaporitic/brine Li.
Transform boundaries
Plates slide laterally past one another with little magmatism, so transforms rarely create deposits directly. Their value is structural: deep transform and strike-slip faults act as long-lived plumbing that can focus fluids from adjacent systems and localise pull-apart basins.
Lateral shear → crustal-scale fault conduits → fluid focusing & pull-apart basins (rather than melt generation).
Intraplate & ancient cratons
Away from boundaries, two engines dominate. Mantle plumes / large igneous provinces deliver magmatic Ni-Cu-PGE sulphides; and thick, cold, ancient cratonic keels are where diamond-bearing kimberlites survive their fast ascent from the deep mantle.
Plume magmatism (LIP Ni-Cu-PGE) · deep kimberlite ascent through stable cratonic lithosphere (diamond).
Boundary type → deposit type, at a glance
| Boundary / setting | Signature deposits | Key metals |
|---|---|---|
| Subduction arc | Porphyry · epithermal · skarn · arc VMS | Cu Au Mo Ag |
| Continental collision | Orogenic gold · Sn-W granites · Li pegmatites | Au Sn W Li |
| Mid-ocean ridge / back-arc | VMS / seafloor massive sulphide · ophiolite chromite | Cu Zn Au Cr |
| Continental rift | Carbonatite REE-Nb · Li brines · sed-hosted Cu | REE Nb Li Cu |
| Transform | No primary class — structural fluid pathways | — |
| Intraplate / craton | LIP Ni-Cu-PGE · kimberlite diamond · IOCG | Ni Cu PGE Diamond |
♻️ The Wilson cycle — settings are recycled
Plate settings are not permanent — they cycle. An ocean basin opens at a rift, widens at a ridge, then closes by subduction until two continents collide; later the suture can rift apart again. This Wilson cycle means a single piece of crust can pass through several ore-forming settings over hundreds of millions of years. It is also why ophiolites — slices of old ocean floor, carrying their VMS and chromite — end up stranded high in mountain belts.
📌 Why deposits cluster — metallogenic belts
Deposits are not scattered at random: they cluster in metallogenic belts and provinces that trace a former boundary. The Andean porphyry belt follows an active subduction margin; the Iberian Pyrite Belt traces a Variscan collision; the Central African Copperbelt follows a Proterozoic rift basin. Find the right boundary at the right age and you have narrowed the search from a continent to a belt.
🔋 Critical metals — where each one forms
Lithium — continental rifts, salar brines and collision-zone pegmatites. Rare earths & niobium — carbonatites along old rifts. Copper — subduction arcs. Nickel-cobalt-PGE — mantle-plume large igneous provinces. Tin-tungsten — collisional granite belts. Every critical-metal search starts by asking which boundary, at which age, built it.
🗺️ Interactive plate-boundary map
The 241 PB2002 boundaries, coloured by type. Click any segment for the deposit families that type controls. Click a legend chip to show/hide a type.
☄️ Impacts — craters & meteorites
Confirmed terrestrial impact structures (Wikidata / Earth Impact Database) and recorded meteorite landings (NASA / Meteoritical Society, 51,776 catalogued, 38,246 with a published location). Impacts drive shock metamorphism (coesite, stishovite, shocked quartz, suevite) and locally impact diamonds (Popigai). Click a feature for its fiche; click a chip to toggle a layer. Click a mineral to open it in the Gem & Mineral database.
🌎 Antarctic polar view — the meteorites Mercator cannot show
This view uses Antarctic Polar Stereographic (EPSG:3031), in which the South Pole is an ordinary point on the map. The world map above cannot show these records honestly: Web Mercator stops at 85.0511°, so everything further south is clamped onto that line rather than placed. You can switch between NASA Blue Marble polar imagery, served natively in this projection by NASA EOSDIS GIBS, and a dark analytical basemap that draws a simplified cartographic outline of Antarctica for contrast — the meteorite positions are identical in both. Zoom in and the markers grow with the view. Where thousands of specimens share one published coordinate the marker stays one marker, because that is one collection area, and clicking it opens the records that belong to it rather than scattering them across positions nobody recorded.
❄️ Why are so many meteorites found in Antarctica?
Meteorites do not fall more frequently in Antarctica than elsewhere on Earth. Antarctica is exceptional because its cold, dry environment preserves them, while the slow movement of the ice can transport and concentrate meteorites in blue-ice areas known as meteorite stranding zones. Wind ablation and local ice-flow conditions expose old ice at the surface, where dark meteorites are comparatively easy to spot against the ice. As a result, Antarctica contains an unusually large share of the meteorites recovered on Earth.
- Preservation — cold, dry conditions can preserve meteorites for very long periods.
- Ice transport — meteorites buried in the ice are carried along as the ice sheet flows.
- Stranding zones — where ice flow slows or is obstructed and surface ice is removed, meteorites can become concentrated and exposed in blue-ice areas.
- Visibility — dark rocks stand out strongly against blue and white ice, and there is little terrestrial rock or vegetation to hide them.
These concentrations therefore reflect preservation, ice transport and search conditions — not a higher extraterrestrial impact rate.
Sources: NASA Earth Observatory; ANSMET (Antarctic Search for Meteorites), Case Western Reserve University.
🛢️ Petroleum provinces — subsurface context
The world's petroleum provinces, as defined and assessed by the USGS. They are here for one reason: a province where petroleum has been assessed is a province whose deep architecture has been studied far more than almost anywhere else on Earth — decades of seismic, wells, formation tops, temperature, pressure and basin modelling. That record describes sedimentary basins, stratigraphy, faults, traps, depth, thermal history and fluid migration, and all of it is useful when reading a completely different mineral system. Click a province for what the assessment recorded.
🛢️ Oil & gas fields — subsurface context
Individual documented fields, from national regulators — not provinces. A petroleum province is a basin-scale assessment domain; an oil or gas field is one accumulation, with a name, an operator and a licence. The province above says where the deep subsurface has been investigated at all; a field says where that investigation is at its most intense, because a producing field is drilled, logged, pressure-tested and modelled for decades. Click a field for what its regulator publishes.
🎯 Mineral prospectivity — where the controls converge
A Weights-of-Evidence model learns, from the 166,000 mines it was trained on, how strongly each geological control co-occurs with a known deposit — then produces a relative prospectivity surface across the modelled domain. Below: the learned strengths, the held-out result, and the most under-explored convergence zones. It is a relative screening signal, not a probability: it ranks ground against other ground, never states a chance that a deposit exists, and only drilling confirms.
⏳ Paleo-tectonics — deposits live on ancient boundaries
Most ore was made at a boundary that no longer exists where the deposit now sits. Iberia's tin-tungsten belt formed in a Variscan collision ~300 million years ago; Bayan Obo's rare earths formed in a Proterozoic rift. To explore by setting you have to reconstruct the plates back through time. Plate-reconstruction models (GPlates / PALEOMAP) let you rewind continents from today to ~540 Ma and ask: what boundary was here when the metal formed? A paleo-reconstruction time-slider is planned as a follow-on layer on the asset map.
Sources & further reading
- Bird, P. (2003). An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems 4(3), 1027. — the PB2002 boundary model used in the map overlay (public domain).
- Sillitoe, R.H. (2010). Porphyry copper systems. Economic Geology 105(1), 3–41.
- Groves, D.I. et al. (1998). Orogenic gold deposits. Ore Geology Reviews 13, 7–27.
- Hronsky, J.M.A. et al. (2012). A unified model for gold mineralisation in accretionary orogens. Mineralium Deposita 47.
- Müller, R.D. et al. (2018). GPlates: building a virtual Earth through deep time. G-Cubed 19. — open plate-reconstruction software/service.
- Scotese, C.R. PALEOMAP Project — paleogeographic reconstructions (educational use).
- Macrostrat · USGS plate-tectonics datasets · NASA SEDAC plate boundaries (open data).
Plate-boundary geometry: PB2002 (Bird 2003) via the public-domain tectonicplates dataset. Boundary→deposit links summarise standard economic-geology literature and are indicative geological context, not a resource or discovery claim.