Enhanced Weathering Triggered the Transient Oxygenation Event at ∼1.57 Ga

Abstract

Abstract The mid‐Proterozoic (∼1.8–0.8 Ga) is characterized by low atmospheric oxygen and pervasive oceanic anoxia, with transient oxygenation events. One of the oxygenation events happened at ∼1.57 Ga, during which atmospheric O 2 may have reached ≥4% present atmospheric level (PAL) and thus promoted the evolution of multi‐cellular eukaryotes. The cause of this oxygenation event, however, remained unknown. Here, we report δ 202 Hg, ∆ 199 Hg, P concentration, Rb/Al, and ε Nd (t) data across the ∼1.57 Ga oxygenation event in the Gaoyuzhuang Formation of North China. The positive δ 202 Hg, ε Nd (t), and negative Δ 199 Hg shifts, plus the accompanied peaks in Rb/Al, P, and I/(Ca + Mg), suggest that this oxygenation event was likely resulted from enhanced weathering of intermediate to mafic rocks, which may have promoted primary production via increasing P influx to the ocean and led to the rise in oxygen levels. The data indicate that enhanced weathering input could trigger transient oxygenation events during the mid‐Proterozoic.