Fig. 2 | Nature Communications

Fig. 2

From: Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing

Fig. 2

Diagram of key processes in the COPSE model. a Carbon cycle. Hydrospheric CO2 is transferred to sediments as organic C or carbonate by burial (B). Sedimentary C is returned to the ocean/atmosphere via weathering and metamorphism (W). Buried organic C is isotopically lighter than the carbon it is derived from. Burial of reduced organic carbon results in a net source of O2, whereas oxidative weathering of sedimentary organic carbon consumes O2. b Sulphur cycle. Burial of reduced pyrite is a net source of O2, whereas oxidative weathering of sedimentary pyrite consumes O2. c Oceanic phosphorus (P) cycle. Dissolved, bio-available P is delivered to the ocean by chemical weathering via rivers, and is buried either as organic phosphorus, or with iron or calcium minerals. Dashed lines show burial processes that are influenced by bioturbation (but are not considered so in the baseline model)

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