Abstract 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… Click to show full abstract
Abstract 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. Δ FMQ − 8 ), extremely oxidized oxygen fugacity in post-Hadean magmas (e.g. Δ FMQ + 10 ) and contradictory oxygen fugacities recorded in ore-related porphyry magmas ( Δ NNO + 5 vs Δ NNO + 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 δ K to constrain the D zircon / whole rock 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.
               
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