Volcanism takes a back seat driving global iron deposition after the Great Oxidation Event

Clarifying linkages between oxygenation and the evolution of complex life requires identification of foundational controls on oxygenation, deoxygenation, and habitability. Massive iron formations are uniquely sensitive to levels of marine oxygen. Yet, temporal uncertainties hinder global comparison of these archives, especially after Earth’s initial surface oxygenation. We present new high-resolution geochronologic data associated with iron deposition on the Superior Craton after the Great Oxidation Event (GOE). By combining our new magmatic age constraints linked with iron deposition ( ²⁰⁶ Pb/ ²³⁸ U dates of 1886.5 ± 1.4, 1887.16 ± 0.91, and 1885.8 ± 1.9) with a revaluation of existing datasets and a simple, yet powerful, global summative approach to post-GOE iron deposits, we can critically assess conditions triggering post-GOE iron deposition and the factors influencing the trajectory of marine oxygen. Our results challenge the paradigm that extensive volcanism directly triggered ~1.88 Ga iron deposition. Instead, we propose that depressed atmospheric O ₂ and paleogeography (via ocean gateways and Ekman-induced upwellings) enhanced early Paleoproterozoic global iron deposition and controlled large-scale patterns of ocean oxygenation and deoxygenation through time.