Fig. 4: Reconstruction of ocean redox landscape and associated Fe biogeochemical cycle in the Paleoproterozoic oceans during the Lomagundi Event.
From: Expansion of the aerobic iron biogeochemical cycle during the Paleoproterozoic Lomagundi event

The data show that Fe(II) was significantly oxidized and removed from seawater in mildly oxic deep oceans while dissolved Mn(II) was still transported to well-oxygenated shelf environments where it was quantitatively oxidized and removed from seawater.