This page was created by Thunder Gold Corp. All statements about mineral resources refer to the January 19, 2026 NI 43-101 mineral resource estimate prepared by Micon International Limited. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
Greenstone belt gold deposits
| Greenstone belt gold deposits account for a large share of the gold ever mined from Archean terranes. Thunder Gold Corp. (TSXV: TGOL | OTCQB: TGOLF | FSE: Z25) works in one of them: the Shebandowan Greenstone Belt, where its 100%-owned Tower Mountain gold project sits about 40 km west of Thunder Bay, Ontario, and where a January 19, 2026 resource estimate by Micon International Limited totalled roughly 3.5 million ounces. |
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What Is a Greenstone Belt?
A greenstone belt is a long, narrow belt of ancient volcanic and sedimentary rocks that has been metamorphosed at low grade, giving the rocks a characteristic green colour and the belt its name. Most greenstone belts are Archean, older than 2.5 billion years, and they preserve the remnants of volcanic arcs, ocean floor and sedimentary basins that were assembled and deformed during early crustal growth. Internally they are a layered mix of mafic and ultramafic flows, intermediate to felsic volcanic rocks, volcaniclastic and sedimentary units, and later granitoid intrusions. That mix, deformed by faults and folds, created the plumbing that gold-bearing fluids later exploited.
Why Greenstone Belts Host So Much Gold
Three ingredients explain the concentration of gold. First, the volcanic sequences in these belts began enriched in gold relative to average crust. Second, deformation created long-lived, deeply penetrating structures that focused fluid flow for millions of years. Third, syn- to post-tectonic intrusions supplied heat and, in some systems, magmatic fluid. Where the three combine, gold is stripped from large volumes of rock and re-deposited in structurally prepared traps: shear zones, fold hinges, competency contrasts and alteration halos. The result is a family of deposits rather than a single type, which is why geologists divide greenstone belt gold deposits into orogenic and intrusion-related groups, with overlap between them in the field.
Time is part of the explanation too. Greenstone belts are among the oldest preserved rock packages on Earth, so their structures have been re-activated repeatedly and their volcanic sequences have had hundreds of millions of years of fluid flow through the same plumbing. Repetition is what builds a deposit: each deformation event re-opens pathways, remobilises gold and concentrates it further into the most favourable traps.
The Two Main Families of Greenstone Belt Gold Deposits
Orogenic gold deposits form from metamorphic fluids in and around major shear zones, with gold in quartz-carbonate veins and their altered wallrock. They do not require an intrusion. Intrusion-related gold deposits are driven by cooling magmas, with gold in disseminated sulphide, sheeted veins and breccia systems around or within the intrusive body. Both styles can occur in the same belt, and both can be bulk-tonnage or narrow. Classification matters for exploration because it shapes the target: an orogenic explorer maps structure, while an intrusion-related explorer maps alteration halos, magnetic signature and intrusion contacts.
Why Archean Belts Host So Much Orogenic Gold
Orogenic gold, the style that dominates Archean greenstone belts, is produced by metamorphic fluids released as buried volcanic sequences are heated and deformed. Those fluids dissolve gold along with silica, carbonate and sulphur, migrate along faults and shear zones, and precipitate gold where pressure, temperature and chemistry change abruptly. Greenstone belts provide the necessary conditions in one place: thick gold-bearing volcanic piles, large fault systems that reach deep into the crust, and chemical traps in iron-rich or carbonate-altered rock. Archean terranes are widely regarded as hosting a large share of the world’s orogenic gold endowment, and Ontario’s historic gold districts sit within belts of this age.
What to Check in Any Greenstone Belt Project
The criteria below apply to almost any greenstone-hosted gold project, whether it is grass roots or advanced.
| What to check | Why it matters |
|---|---|
| Host-rock package | Volcanic and volcaniclastic units with favourable chemistry |
| Structural setting | Major faults and second-order splays that focus fluid flow |
| Alteration | Carbonate, sericite and chlorite halos associated with gold |
| Intrusive association | Presence, age and composition of nearby intrusions |
| Scale and continuity | Width and continuity of mineralized intervals |
| Infrastructure | Road, rail, power and workforce access |
Reading a Greenstone Belt Project as an Investor
A greenstone belt address is a starting point, not a result. Investors should separate the belt from the project and then look at what has actually been measured. Useful checks include:
- Whether a mineral resource estimate exists, and whether the resource is Indicated, Inferred or both.
- The cut-off grade, gold price assumption and recovery used, since these move the headline ounces.
- Strip ratio and strip-adjusted grade, which indicate how much waste must be moved per unit of gold.
- Cost per ounce discovered, a measure of how efficiently drilling has converted dollars into resource.
- Whether any part of the belt position is untested, because that is where future ounces come from.
The Shebandowan Greenstone Belt and Tower Mountain
The Shebandowan belt lies in Northwestern Ontario, west of Thunder Bay. Thunder Gold holds a 100%-owned position in the eastern part of the belt: roughly 7,000 hectares, comprising 401 single-cell mining claims, 24 boundary claims and 8 patented claims, surrounding the Tower Mountain Intrusive Complex. The property boundary sits about 3 km south of the Trans-Canada Highway 11/17, with rail and power corridors 3 to 5 km away. Because the ground surrounds a large intrusive complex, it offers an intrusion-related gold target inside a belt that also has a long history of orogenic gold exploration. Less than 20% of the complex perimeter has been drill tested, and the current resource footprint covers only about 1,800 m by 500 m of the intrusive contact. The property also sits in a settled mining jurisdiction, where exploration and assessment work is filed publicly and governed by the Ontario Mining Act.
Following the Belt Story
Belt-level geology matters because it frames what comes next. The Tower Mountain gold project page covers ownership, infrastructure and the current resource, the Tower Mountain geology page explains the intrusion-related setting, and gold exploration in Ontario places the Shebandowan belt alongside the province’s other gold districts. The drill results page logs every intercept as it is released.
Frequently Asked Questions
Q: What are greenstone belt gold deposits?
A: They are gold deposits hosted in ancient, low-grade metamorphosed volcanic and sedimentary belts, mostly Archean. Gold was stripped from gold-enriched volcanic sequences by fluids focused along deep structures, then deposited in shear zones, folds, competency contrasts and alteration halos around intrusions.
Q: Why do greenstone belts host so much gold?
A: Gold-enriched volcanic rocks, long-lived deep structures that focused fluid flow, and syn- to post-tectonic intrusions that supplied heat and locally magmatic fluid. Where all three coincide, large volumes of rock are leached and gold is re-deposited in structurally prepared traps.
Q: Where is the Shebandowan Greenstone Belt?
A: The Shebandowan Greenstone Belt lies in Northwestern Ontario, west of Thunder Bay. Thunder Gold Corp. holds a 100%-owned position in its eastern part, where the Tower Mountain gold project surrounds the Tower Mountain Intrusive Complex about 40 km from the city.
Q: What should investors check in a greenstone belt project?
A: Look for a mineral resource estimate and its category, the cut-off grade and gold price assumption, metallurgical recovery, strip ratio, cost per ounce discovered, infrastructure access and whether parts of the belt position remain untested. Belt location alone is not evidence of value.
Q: Are greenstone belt gold deposits all the same type?
A: No. Geologists separate orogenic deposits, formed from metamorphic fluids in and around shear zones, from intrusion-related deposits driven by cooling magmas. Both occur in greenstone belts, and both can be bulk-tonnage or narrow, so the deposit style shapes the exploration approach.
Shebandowan Greenstone Belt gold
| The Shebandowan Greenstone Belt gold story is a story about location as much as geology. The belt is an Archean volcanic and intrusive terrane in Northwestern Ontario, and it hosts Thunder Gold Corp.’s Tower Mountain gold project. Thunder Gold Corp. (TSXV: TGOL | OTCQB: TGOLF | FSE: Z25) holds a 100%-owned position of roughly 7,000 hectares in the eastern part of the belt, about 40 km west of Thunder Bay, surrounding the Tower Mountain Intrusive Complex. |
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Where the Shebandowan Greenstone Belt Sits
The belt runs through the Thunder Bay district, west of the city, in a region already served by the Trans-Canada Highway 11/17, rail lines, hydro corridors and the international port of Thunder Bay. For exploration and eventual development, that setting matters as much as the geology. Thunder Gold’s property boundary lies about 3 km south of the highway, with rail and power corridors 3 to 5 km away, meaning no fly-in camp and no permanent access road construction of the scale required in remote camps. A local workforce of roughly 110,000 people lives in Thunder Bay. That combination is unusual among Archean belts, most of which are remote and require fly-in camps and winter roads. Accessibility is one reason the Company reports all-in drilling costs of roughly C$250 to C$275 per metre, among the lowest in Canada.
Rocks, Assemblages and the Belt Name
The belt preserves Archean volcanic, volcanoclastic and intrusive rocks, grouped for mapping purposes as the Shebandowan Assemblage. These are the host rocks at Tower Mountain. Within them, the Tower Mountain Intrusive Complex is described by the Company as the largest exposed calc-alkalic intrusive complex in the eastern Shebandowan Greenstone Belt, and it is multi-phase: syenites, monzonites, diorites and gabbros, with magmatic-hydrothermal events dated at 2692 to 2689 Ma. Gold is hosted in carbonate-sericite-chlorite alteration around the intrusive contact, extending more than 500 m west and remaining open.
Shebandowan Greenstone Belt Gold at a Glance
| Attribute | Detail |
|---|---|
| Location | West of Thunder Bay, Northwestern Ontario |
| Age and setting | Archean volcanic, volcanoclastic and intrusive rocks |
| Host assemblage | Shebandowan Assemblage |
| Key intrusion | Tower Mountain Intrusive Complex, 2692-2689 Ma |
| Thunder Gold ground | About 7,000 ha: 401 single-cell claims, 24 boundary claims, 8 patented claims |
| Current resource | About 3.5 Moz Au Indicated and Inferred, effective January 19, 2026 |
Why This Belt Attracts Exploration
The belt combines the ingredients that drive gold exploration almost anywhere in the Archean: favourable volcanic host rocks, major deformation, and intrusive bodies that supplied heat and fluids. Those ingredients explain why Thunder Gold’s ground is grouped around an intrusive complex rather than a single structure. They also explain the way the Company explores: mapping alteration, tracking magnetic lows created when magnetite was destroyed, and using the direct correlation between disseminated pyrite and gold grade to prioritise targets. Interpretations of this kind belong to the Company and are refined as drilling proceeds.
The ingredients the Company maps and drills for are consistent from target to target:
- Volcanic, volcanoclastic and intrusive host rocks of the Shebandowan Assemblage.
- Carbonate-sericite-chlorite alteration halos around the intrusive contact.
- Disseminated, fine-grained pyrite that correlates directly with gold grade.
- Broad magnetic lows created where alteration destroyed magnetite.
- Structural and lithological contacts that channelled mineralizing fluids.
Thunder Gold’s Position in the Belt
Thunder Gold is not only a Tower Mountain company within the belt. Recent corporate activity includes the option of the Electra property in the Shebandowan belt in April 2026, the purchase of a freehold patent and the sale of the Seagull Lake property in May 2026, and a $215,000 Ontario Junior Exploration Program grant awarded in March 2026. The Company also filed its NI 43-101 technical report in March 2026 and announced a new gold discovery in April 2026. Together these moves show a company consolidating a position in one belt rather than spreading across several jurisdictions, which reduces logistical and permitting complexity. For shareholders, that concentration is the practical meaning of Shebandowan Greenstone Belt gold exposure.
Why Belt-Scale Geology Matters to Shareholders
A company’s position in a belt determines how much of the story it controls. Thunder Gold holds roughly 7,000 hectares around the Tower Mountain Intrusive Complex, so the alteration halo, the intrusive contact and the magnetic lows that track it fall largely inside one contiguous land package. That differs from holding scattered claims along a structure, because contiguous ground can be drilled systematically, permitted as one project and, if studies support it, served by one access route and one processing site. Less than 20% of the complex perimeter has been tested, so the land package is also where the next tranche of ounces most likely comes from.
Community and Traditional Territory
The Tower Mountain property lies within the traditional territories of Fort William First Nation. The Company has added board members including Glenn Nolan, former Chief of Mitaanjigamiing First Nation, which supports early relationship building ahead of any permitting process. At operation scale, the Company has referenced potential for more than 1,000 long-term jobs, a figure that speaks to the belt’s accessibility rather than to any completed feasibility work. Ontario’s Mining Act and NI 43-101 disclosure standards govern how the project must be advanced and reported. Early engagement also reduces schedule risk, since permitting for any future operation in Ontario involves Crown consultation with First Nations alongside provincial approvals. That is not a permit or a development decision today: Tower Mountain remains an exploration project, and mineral resources are not mineral reserves.
What Comes Next in the Belt
The near-term newsflow at Tower Mountain is belt-scale in its ambition: a 15,000 to 25,000 metre 2026 infill and expansion program, an updated resource and an initial preliminary economic assessment targeted for late 2026 and early 2027 by the Company, and drilling that tests a perimeter where less than 20% has been tested. Mineral resources are not mineral reserves and do not have demonstrated economic viability. Read the Tower Mountain gold project overview for the asset in full, the Tower Mountain geology page for the deposit setting, gold exploration near Thunder Bay for the local context, and Tower Mountain drill results for the latest assays.
Frequently Asked Questions
Q: What is the Shebandowan Greenstone Belt?
A: It is an Archean greenstone belt in Northwestern Ontario, west of Thunder Bay, made up of metamorphosed volcanic, volcanoclastic and intrusive rocks. Thunder Gold Corp.’s Tower Mountain gold project, about 7,000 hectares, sits in the eastern part of the belt.
Q: Why is the Shebandowan belt favourable for gold exploration?
A: It combines gold-enriched Archean volcanic host rocks, major deformation that focused fluid flow, and intrusive bodies that supplied heat and fluids. Thunder Gold’s ground surrounds the Tower Mountain Intrusive Complex, the largest exposed calc-alkalic intrusive complex in the eastern part of the belt as described by the Company.
Q: Where is the Tower Mountain Intrusive Complex?
A: It lies within the Shebandowan Greenstone Belt about 40 km west of Thunder Bay, Ontario, roughly 3 km south of the Trans-Canada Highway 11/17. It is a multi-phase complex of syenites, monzonites, diorites and gabbros with mineralizing events dated at 2692 to 2689 Ma.
Q: What infrastructure serves the belt?
A: The property boundary is about 3 km south of Highway 11/17, with rail and power corridors 3 to 5 km away, and the international port of Thunder Bay with Saint Lawrence Seaway access nearby. Workers can live in Thunder Bay, roughly 40 km from the project.
Q: Does Thunder Gold hold other ground in the Shebandowan belt?
A: Yes. In April 2026 the Company optioned the Electra property in the Shebandowan belt, and in May 2026 it purchased a freehold patent and sold the Seagull Lake property. Tower Mountain remains the flagship asset at roughly 7,000 hectares.