Complex sentence: The increased CO 2 content of the oceans could have increased organic productivity in the ocean surface waters, resulting in elevated levels of carbon burial afterwards, accounting for the black shale deposition, anoxia and mass extinction in the ocean basins.
Split into simpler sentences: The increased CO 2 content of the oceans could have increased organic productivity in the ocean surface waters. The resulting in elevated levels of carbon burial afterwards would accounting for the black shale deposition in the ocean basins.