Metals are ubiquitous in volcanic environment, present in quantities in atmospheric emissions, dissolved in springs and lakes whenever present, and at depth in dissected ancient volcanoes associated with ore deposits. What carriers, if not the magma, are responsible for their mobility and what are the effects of magmatic-hydrothermal systems present at many volcanoes? We address these questions through a case study at White Island, an andesitic volcano off the coast of New Zealand. Studies were carried on recent ejecta and a variety of hydrothermal features, in the view of characterizing the volatile transport of metals. Late sulfide saturation in the magmatic chamber concentrates Cu, Au, Ag and Ni in immiscible melts, available for subsequent enrichment of a magmatic vapor phase upon destabilization. In the subsurface environment, the hyper-acidic crater lake acts as a metal sink, scrubbing hydrothermal fluids injected at depth. Sulfides precipitate near subaqueous vents whereas other chalcophile elements are segregated by molten sulfur at the bottom of the lake. Fumarolic gases and aerosols are enriched in metals with emission rates in the range 1-10 kg/d for As, Pb, Zn and Se. The copper content is relatively low compared to other volcanoes, suggesting precipitation in the subsurface environment at higher temperature.

Celine Mandon is finishing her PhD studies at the Victoria University of Wellington in New Zealand. Her areas of interest are volcanology and geochemistry. Her PhD led her to study New Zealand’s most active volcano, White Island, in the view of constraining the transport of metals in active magmatic-hydrothermal systems. She has previously worked on sulfur dioxide emissions from Mount Etna and the use of hydrothermal waters in monitoring volcanic activity at Vulcano, as part of her master’s studies.