Volcanic-Hosted Resources

Volcanoes and volcanic rocks are hosts to economically very significant quantities of natural resources. Initially, we provide a brief overview of volcanic-hosted ore deposits and their typology. We then focus predominantly on the geology of the principal ore deposit types that characterise volcanic successions and some high-level subvolcanic intrusive settings. These are divided into epithermal precious metal, iron oxide copper–gold (IOCG), volcanic-hosted uranium, komatiitic-hosted nickel sulphide, kimberlitic-hosted diamonds, and volcanic-hosted massive sulphide (VMS) deposits. Epithermal gold deposits represent, in terms of exploration expenditure, the most important type of volcanic-hosted resource thus warranting the greatest attention. We discuss these in terms of today’s active geothermal systems that occupy the same volcano-tectonic environments as the fossil hydrothermal systems which host them and further assess these in more detail by dividing them by volcanic landform or feature and facies associations. IOCG deposits are a relatively new family of hydrothermal ore deposit types, only some of which have a clear spatial and genetic relationship to subvolcanic and volcanic processes and rocks. Most volcanic-hosted uranium deposits are relatively small and low grade; however, some larger and higher-grade resources are known. Both komatiite lavas and komatiite intrusions in Archean (and some Proterozoic) greenstone terrains locally host significant orthomagmatic nickel sulphide (Ni, Cu, PGE) deposits and are one of the world’s major sources of Ni production. Kimberlites and lamproites transport diamond xenocrysts in their “mantle cargo” to the Earth’s surface, where they erupt explosively to form pipe-like bodies representing the remains of volcanoes and their vent systems. Polymetallic VMS deposits represent a distinctive, although highly variable, submarine magmatic–hydrothermal ore deposit type having direct genetic links to both a submarine environment and volcanism, including subvolcanic intrusions. Consideration is also given to volcanic rock reservoirs in hydrocarbon exploration which, with significant exploration successes over the past fifteen years, represent a new frontier field of petroleum exploration globally. Finally, we discuss geothermal energy, which is likely to become a more significant energy resource in the future.