Abstract:

Abstract:  This paper, through listing the genetic type names of hydrothermal gold deposits presented in literatures, reveals that the existing genetic classifications of hydrothermal deposits are scientifically illogical, confusing and abusive, without satisfactory connection to logics in other geoscience disciplines. This greatly hinders the ore geological training, research and exploration targeting, and is resulted from a conceptual gap of the geological processes occurred at depths less than 10 km and temperatures of 50300 ℃. Hence we propose a concept of epizonogenism to describe the geological processes occurred at depths of <10 km and temperatures of 50300 ℃. In correspondence, hydrothermal deposits are classified into three endmembers, namely epizonogenic, metamorphic and magmatic. It is confirmed that the epizonogenic fluids are characterized by lowsalinity and CO₂poor, the metamorphic fluids by lowsalinity and highcontent of CO₂rich, and the magmatic fluids by highsalinity and variable content of CO₂. The magmatic hydrothermal systems contain multiple daughtercrystalsbearing and CO₂rich highsalinity fluid inclusions; the metamorphic deposits contain lowsalinity CO₂rich fluid inclusions; and the epizonogenic hydrothermal systems contain neither daughtercrystalbearing nor CO₂rich/bearing fluid inclusions, but are populated by aqueous fluid inclusions.

Key words: epizonogenism, orefluid, fluid inclusion, hydrothermal deposit, genetic type of ore deposit