Insight into zircon REE oxy-barometers: A lattice strain model perspective

Zircon rare earth element (REE) oxy-barometers have been widely used to calculate magma oxygen fugacity. However, sometimes confusing results are obtained, such as extremely reduced oxygen fugacity in Hadean magmas (e.g. ΔFMQ−8), extremely oxidized oxygen fugacity in post-Hadean magmas (e.g. ΔFMQ+10) and contradictory oxygen fugacities recorded in ore-related porphyry magmas (ΔNNO+5 vs ΔNNO+1). To address these issues, this work reviews the underlying assumption of zircon REE oxy-barometers, the lattice strain model. By introducing a geochemical filter to identify clean, inclusion-free zircon and a new parameter δK to constrain the Dzircon/wholerock deviation from the lattice strain model, we systematically re-evaluate the common zircon REE oxy-barometers, address the issues noted in Hadean, post-Hadean and ore-related magmas, and provide an alternate approach to using zircon REE in studies of magmatic processes.