Long-term Variation of Zircon Trace Element Composition

The zircon Hf isotope record is fundamentally governed by differences in compatibility between Lu and Hf in the mantle versus the crust. Trends in zircon epsilon Hf over time have therefore been tied to plate tectonic processes such as subduction, arc magmatism, and convergence, as opposed to slab rollback, rift magmatism, and extension. In contrast, detrital zircon trace element data are most commonly used as "tracers" of source lithology. However, some zircon trace element ratios are also strongly leveraged by compatibility, suggesting that, like zircon Hf isotope ratios, the long-term record of zircon trace element composition may reflect the overall plate tectonic evolution of the planet. We have added new detrital zircon trace element data from central Australia to a compiled global dataset in order to assemble a first-order zircon trace element record that spans >4 billion years. Long-term secular variation of some key zircon trace element ratios, such as Yb/U, are closely aligned with the zircon Hf isotope record. Of particular note is a Neoproterozoic to Cambrian period when both zircon epsilon Hf and Yb/U reach their minima. This era of anomalous zircon geochemistry possibly records a period of extensive subduction of continentally-derived material.