BACKGROUNDAs an important mineralization element, mercury is widely distributed in different geological bodies and participates in diagenesis and mineralization. With the rapid development of mass spectrometry technology, the field of mercury isotope geochemistry has made remarkable progress. Mercury isotopes have been widely used to trace the biogeochemical processes of the earth's surface and mercury pollution. In recent years, mercury isotopes have been applied to reveal the evolution of planets, identify large igneous provinces in geological history, and trace the sources of mineral deposits.

OBJECTIVESTo summarize the mercury isotope compositions of different geological reservoirs (meteorites, terrestrial rocks, coal, sediments, volcanic emissions, epithermal deposits) and investigate the factors controlling the Hg isotope fractionation during ore-forming processes in epithermal deposits.

METHODSLiterature reviewed that included published data from this research group and others.

RESULTSBased on previous studies, the isotope composition of mercury in different geological reservoirs was systematically studied. The mercury isotopic composition of geological reservoirs such as meteorites, magmatic rocks, metamorphic rocks, sedimentary rocks, and volcanic gases varied greatly, and some samples also contained non-mass fractionation information. The occurrence and isotopic composition characteristics of low-temperature hydrothermal deposits (modern hot springs, mercury deposits, lead-zinc deposits, antimony deposits, gold deposits) was the focus of this review, and the basic framework of the mercury isotope system construction. Combined with the latest research results, a comprehensive summary of the mercury isotope fractionation mechanism that may have occurred in the mineralization process of the deposit was carried out. The mass fractionation of mercury isotopes in hydrothermal deposits may be caused by fluid volatilization or boiling, condensation, redox reactions, and sulfide precipitation. The non-mass fractionation of mercury isotopes in rocks and ores may be the product of mercury photochemistry during the geological history, or the inheritance of a specific source rock information.

CONCLUSIONSIn the future, mercury isotope has great application potential in tracing the ore-forming source of low-temperature hydrothermal deposits and characterizing the evolution of ore-forming fluids.