Scientists at the Chinese Academy of Sciences have found evidence that the great Permian extinction was due to ozone depletion due to large-scale volcanic eruptions. This is reported in an article published in the journal Chemical Geology.
Researchers estimate that 81 percent of all marine animal species and 70 percent of terrestrial vertebrate species disappeared at the end of the Permian period of the Paleozoic era, but the event also affected plant life. The cause of this largest catastrophe in Earth’s history is attributed to trap volcanism in Siberia, as evidenced by massive deposits of pyroclastic flows over an area of about seven million square kilometers.
Scientists analyzed the content of sulfur isotopes (sulfur-33, sulfur-34 and sulfur-36) in microscopic pyrite grains from Permian sediments. Anomalous contents of sulfur-33 and sulfur-36 were found shortly before the end of the period. This cannot be explained by isotope fractionation due to geological processes and requires photolysis of volcanic SO2 under ultraviolet light.
