We are pleased to announce a School Seminar by Dr Hugo Moreira on the topic of: "Opening atmospheric windows to the Earth's evolving mantle"
Abstract:
Plate tectonics exerts a first-order control on Earth’s volatile cycles. Atmospherically-altered surface materials are recycled into the mantle via subduction, while volatiles from the mantle are liberated to the atmosphere via volcanism. This cycle regulates much of Earth’s climate, ocean chemistry and metallogenetic processes within the continental crust. However, tracing the volatile cycles through deep geological time and understanding their effects in the mantle remain a big challenge. For example, the onset of mantle oxidation driven by crustal recycling is a subject of intense debate. This talk presents a new proxy that assesses the fugacity and elemental contents in apatite inclusions shielded in zircon grains to constrain the Earth’s upper mantle oxygen fugacity through time. Our dataset shows relatively oxidised conditions over the last 3.4 billion years, suggesting a dynamic recycling mechanism in the early Earth, potentially powered through oxygenation episodes.