Gold-transporting hydrothermal fluids in the Earth's crust: An introduction

Hydrothermal ore deposits that are exploited for gold include both gold-only deposits, such as orogenic deposits, and gold-bearing examples of the common hydrothermal deposit types that are formed around upper-crustal magmatic centres, in particular porphyry and epithermal deposits. Fluid inclusion data have shown that ore fluids of gold-only deposits are compositionally distinct compared to fluids of other deposit types: Fluids of the latter deposit types are, in contrast, not distinctive, and recent research has been focussed on relating gold content to geochemical and petrological aspects of related magmatic systems and to fluid evolution on migration through the crust. This Special Publication includes an up-to-date summary of thermodynamic parameters of aqueous Au species at high temperatures and pressures, a dataset of fluid inclusion properties and compositions from orogenic deposits of different parts of the world, several comprehensive case studies of different types of gold deposits and their fluids from the USA, Brazil, Egypt, Slovakia and Bulgaria and numerical modelling aimed to define key parameters that affect fluid flow and gold deposition at a range of scales.