Tracing Magmatic Redox Evolution Through Earth's History Using Zircon Geochemistry

The redox state of magmas serves as a key indicator of Earth's evolutionary processes, recording pivotal events such as changes in atmospheric composition, the emergence of life, and major tectonic shifts. This study utilizes zircon oxygen fugacity (ΔFMQ), an igneous oxybarometer, to explore the temporal variations in magma redox states across Earth's history. We find that the zircon ΔFMQ declines from 4.2–3.8 Ga, likely reflecting the Late Heavy Bombardment. A subsequent increase in ΔFMQ from 3.8–3.0 Ga is linked to processes such as water recycling in supracrustal materials and the thickening of continental crust. After 2.5 Ga, fluctuating ΔFMQ trends mirror the cycles of supercontinent formation, where introversion involves the subduction of reduced sediments from interior oceans, and extraversion involves oxidized sediments from exterior oceans. Our findings demonstrate the power of zircon ΔFMQ as a tool for tracing magma redox evolution, shedding light on significant geological processes and their timing in Earth's history.