Fig. 3: Schematic redox state landscape of the Tonian Xuhuai basin.
From: A shallow-water oxygen minimum zone in an oligotrophic Tonian basin
A Idealized basin topography and Proterozoic stratified ocean. Blue dashed line marks the chemocline between the oxic upper ocean and the anoxic deep ocean. Khaki shaded area represents the basement rock. B Schematic representation of the shallow-water oxygen minimum zone (OMZ, green shaded area) in the Xuhuai basin. The relatively higher primary productivity in the nearshore area consumed the dissolved oxygen and maintained the prevalent shallow-water OMZ in an oligotrophic ocean. The insignificant riverine sulfate input relative to the FeHR during this period further prohibited the microbial sulfate reduction and resulted in a ferruginous OMZ. The inset in B shows the proposed variations of O2 (solid black line), Fe2+ (dashed black line), and H2S (dotted gray line) in the water column marked by a dotted rectangle.
