Episodic Organic Carbon Burial During the Phanerozoic Indicated by a New Atmospheric pO2 Record resources.

English Abstract:

A new reconstruction of Phanerozoic atmospheric pO₂, which is based on the δ¹³C of terrestrial organic matter, indicates that at least four major episodes of continuous pO₂ increase occurred over the last 450 million years. Each of these episodes lasted between 20 and 50 million years. The increase in pO₂ during these episodes allowed us to estimate of the amount of organic carbon (OC) that needed to be buried in order to account for the pO₂ increases. The combined total for all four burial episodes is ~4.4x10¹⁹ moles of OC. Using the accumulation of bitumen in the Athabasca tar sands deposit as a measure of scale (1 AE ~1.8 x10¹² barrels), we estimate the amount of OC burial during the burial events to be equivalent to ~2600 Athabasca deposits (see Table).

The timing of the four predicted OC burial events coincides with the formation of economically important coal, oil, and gas deposits. However, the amount of carbon stored in known deposits is ~2-3 orders of magnitude smaller than the amount of OC burial required to account for the pO₂ changes. This suggests that the vast majority of OC buried during the Phanerozoic still remains within its sedimentary host rocks, either as dispersed material, or as undiscovered resources.