THE ROLE OF MAGMAS IN THE FORMATION OF HYDROTHERMAL ORE-DEPOSITS

Magmatic fluids, both vapour and hypersaline liquid, are a primary sou rce of many components in hydrothermal ore deposits formed in volcanic arcs. These components, including metals and their ligands, become co ncentrated in magmas in various ways from various sources, including s ubducted oceanic crust. Leaching of rocks also contributes components to the hydrothermal fluid-a process enhanced where acid magmatic vapou rs are absorbed by deeply circulating meteoric waters. Advances in und erstanding the hydrothermal systems that formed these ore deposits hav e come from the study of their active equivalents, represented at the surface by hot springs and volcanic fumaroles.