Timing and tempo of the Great Oxidation Event

TLDR

The study presents U‑Pb ages for the Ongeluk large igneous province, a Paleoproterozoic equatorial magmatic event in southern Africa. The 2,426‑Ma ages link the Ongeluk magmatism to the earliest Paleoproterozoic glaciation and the onset of atmospheric oxygenation, revealing that oxygen levels oscillated before the irreversible rise and that glaciations and oxygenation were driven by continental assembly, magmatism, and equatorial migration, paralleling Neoproterozoic patterns.

Abstract

Significance We present U-Pb ages for the extensive Ongeluk large igneous province, a large-scale magmatic event that took place near the equator in the Paleoproterozoic Transvaal basin of southern Africa at ca. 2,426 Ma. This magmatism also dates the oldest Paleoproterozoic global glaciation and the onset of significant atmospheric oxygenation. This result forces a significant reinterpretation of the iconic Transvaal basin stratigraphy and implies that the oxygenation involved several oscillations in oxygen levels across 10 −5 present atmospheric levels before the irreversible oxygenation of the atmosphere. Data also indicate that the Paleoproterozoic glaciations and oxygenation were ushered in by assembly of a large continental mass, extensive magmatism, and continental migration to near-equatorial latitudes, mirroring a similar chain of events in the Neoproterozoic.