VMS

• Mineral Exploration and Commercial Interest

  The economic potential of offshore VMS deposits in the Kermadec arc has attracted exploration companies, including Neptune Resources and Nautilus Minerals, which have conducted surveys using:

  • Multi-beam bathymetric mapping
  • Seafloor rock and sediment sampling
  • Environmental and geophysical assessments

  Neptune Resources held prospecting permits over much of the arc and applied for a mining permit at Brothers Volcano in 2008, although these permits expired in 2010. Future commercial interest will likely depend on advancements in deep-sea mining technology and environmental considerations.

• Prospectivity of the Kermadec Arc

  A prospectivity ranking system categorises the volcanoes of the Kermadec arc based on their mineral potential. This assessment, developed by de Ronde et al. (2010), classifies volcanoes into four categories (A to D) based on:

  • Presence of hydrothermal activity
  • Metal concentrations in vent fluids and sulphides
  • Size and longevity of hydrothermal systems
  • Geophysical indicators of buried mineralisation

  The highest-ranked sites, such as Brothers and Rumble II West, show the greatest potential for future resource development.

• Environmental and Scientific Considerations

  While offshore VMS deposits hold promise for future resource extraction, their exploration and potential mining must be balanced with environmental concerns. Hydrothermal vents are unique deep-sea ecosystems, hosting specialised biological communities that rely on chemical energy rather than sunlight. Research efforts continue to assess the ecological impact of potential deep-sea mining activities in the region.

  Furthermore, the Kermadec arc provides valuable analogues for ancient VMS deposits found in land-based mining districts, enhancing our understanding of ore-forming processes and guiding future mineral exploration worldwide.

  The Kermadec arc represents one of the world’s most promising offshore regions for VMS mineralisation, hosting significant deposits of copper, zinc, and gold. Advanced exploration techniques have revealed high-grade sulphide mineralisation, particularly at Brothers, Rumble II West, Clark, and Haungaroa volcanoes. Ongoing research will continue to refine mineral prospectivity models, improve understanding of hydrothermal processes, and evaluate the feasibility of future resource extraction in this dynamic and mineral-rich environment.

Why VMS Deposits are Important

• Economic Value and Resource Supply

  VMS deposits host high concentrations of base and precious metals, often in compact, mineable bodies. They have long supported regional economies – from the ancient mining of copper at Cyprus to major modern operations in Canada, Australia, and Japan. Today, they remain important sources of:

  • Copper - essential for electrification, construction, and electronics
  • Zinc - used for galvanising steel, batteries, and alloys
  • Lead - in batteries and shielding
  • Silver and gold - in electronics, jewellery, currency, and investment

   

  In a world transitioning to low-carbon technologies, the metals from VMS deposits are central to solar panels, electric vehicles, wind turbines, and high-capacity batteries.

   

• Strategic and Critical Minerals

  As countries seek secure and sustainable supplies of critical minerals, VMS deposits are a strong target. Copper, zinc, and cobalt (sometimes found in VMS systems) are classified as critical by many nations due to their role in clean technology, infrastructure, and defence. The geographic distribution of VMS resources offers opportunities to diversify supply chains and reduce dependency on a few dominant producers.

• Scientific Insights

  Modern, actively forming VMS systems on the seafloor-such as those at mid-ocean ridges or in volcanic arcs/back-arcs (e.g. the Brothers volcano, Kermadec arc)-are natural laboratories. Studying them has deepened our understanding of:

  • Hydrothermal circulation in the oceanic crust
  • The role of magmatic and seawater-derived fluids in ore formation
  • Metal transport and precipitation mechanisms
  • Submarine volcanism and microbial life in extreme environments

   

  These insights not only help us locate ancient VMS deposits on land, but also reveal key Earth processes linked to crust formation and plate tectonics.

• Exploration for VMS deposits

  Discovering new VMS deposits relies on recognising key mineral systems features. 

  • Geodynamic setting—typically submarine volcanic arcs or rifted margins—where mafic to felsic volcanic rocks provide heat sources, with metals being leached out of the host rocks and in some cases also contributing metals. 
  • Hydrothermal fluids, driven by magmatic heat, circulate through permeable pathways such as faults, fractures, and porous volcanic units. 
  • Zoned alteration halos with chlorite, sericite, and silica near the vent, grading outward to carbonate and albite assemblages.
  • Geochemically, explorers target enrichments in copper, zinc, lead, silver, and gold, as well as pathfinder elements like barium, antimony, and arsenic. Geophysical surveys are also crucial: electromagnetic methods can detect the conductive massive sulphide lenses, while gravity and magnetics help delineate dense ore bodies and alteration zones. Stratigraphically, VMS deposits are often found at the interface between volcanic rocks and overlying sediments, sometimes marked by chemical exhalative layers like chert, barite, or iron-rich horizons. Metal zoning—typically with copper-gold at the core and zinc-lead-silver in outer zones—provides vectors to the heart of the system. Successful exploration integrates these geological, geochemical, and geophysical features to build predictive models for discovery.
  • VMS deposits, especially ancient ones, are relatively easy to explore due to their distinct geophysical and geochemical footprints. Their formation is tightly tied to volcanic and tectonic settings, allowing predictive models to be developed. Moreover, VMS mines can be compact in size with high-grade ores, leading to smaller environmental footprints per tonne of metal-though legacy environmental issues like acid mine drainage must still be managed.