[1] The OAE is associated with large igneous province volcanism and an extinction event of marine organisms driven by global warming, ocean acidification, and anoxia.
[3] The recovery of the global climate from the injection of large amounts of isotopically light carbon lasted for over a million years.
[2] The negative δ13C excursion preceding the OAE, occurring in the C3 isotopic interval,[11] is believed to reflect volcanic release of carbon dioxide into the atmosphere and its consequent warming of the Earth.
[25] δ7Li measurements indicate an enrichment in isotopically light lithium coeval with the negative δ13C excursion, signifying an increase in silicate weathering amidst the volcanically induced global warming of OAE1a.
This weathering may have buffered the warming effects of large igneous province volcanism and helped to cool the Earth back to its pre-OAE1a state.
[2][30] Nannoconids that were highly calcified suffered significant decline during OAE1a, likely as a consequence of ocean acidification,[22] although this causal relationship is disputed by other authors.
[31] The opportunistic, oyster-like bivalve genus Chondrodonta thrived during OAE1a because of its ability to survive in stressed environments where its competitors could not, and its spike in abundance is often used as a biostratigraphic indicator of the onset of OAE1a.