MERCURY ANOMALIES SHOW PRECISE COINCIDENCE OF SIBERIAN AND THE END-PERMIAN MASS EXTINCTION IN SOUTH CHINA

The temporal coincidence of end-Permian mass extinction in South China with flood basalt eruptions in Siberia is well established but the precise temporal link cannot be resolved because of dating errors of two phenomena (flood basalts and ash layer) that occur in widely separated regions. A solution to this problem comes from assay of mercury concentration and mercury isotope in marine sediments because this can provide both an extinction record and a proxy for distant volcanism within the same sections. Mercury/total organic carbon ratios from three Permo-Triassic boundary sections with a well-resolved extinction record in South China show elevated values (of 0.3 relative to a background of <0.1) that exactly coincides with the 60 kyr extinction interval. This enrichment does not show correlation with redox and sedimentation rate variations within the interval and the mercury enrichment is therefore interpreted to be a primary signal of Siberian volcanism. Potentially the entire extrusive volume of this province (~3‒4× 10⁶ km³) may have erupted in < 60 kyr allowing little time for recovery between individual eruption events. This may present the solid evidence revealing the trigger of the P-Tr extinction, and solved out the long-debated cause of the largest extinction of Earth life.