Breakthrough in understanding the mechanism and application of mass-independent Sn isotope fractionation

Tin (Sn) is one of the earliest metal elements used by humans and a strategic critical metal. It possesses the largest number of stable isotopes in the periodic table and has wide applications in fields such as geology, archaeology, and planetary science. In recent years, mass-independent Sn isotope fractionation (Sn-MIF) has been discovered in both planetary samples and laboratory experiments. However, its formation mechanisms and potential for geological applications remain to be further explored. Recently, a research team led by Professor Li Weiqiang from the School of Earth Sciences and Engineering at Nanjing University published their latest findings in the Proceedings of the National Academy of Sciences (PNAS). Through systematic experiments involving ultraviolet light, and magnetic field control, the team demonstrated that mass-independent Sn isotope fractionation is driven by the magnetic isotope effect. The study also revealed, for the first time, the variation of Sn-MIF with magnetic field strength and observed differences in Sn-MIF behavior under ultraviolet versus solar irradiation. This research resolves a long-standing debate regarding the mechanism of Sn-MIF and provides a potential new proxy for tracing Earth’s environment before the Great Oxidation Event.