Role of oxygen in the biotic recovery following mass extinction

Article By:

Pietsch, Carlie Department of Earth Sciences, University of Southern California, Los Angeles, California.

Last reviewed:2015

DOI:https://doi.org/10.1036/1097-8542.YB150675

The end-Permian mass extinction, which occurred approximately 252 million years ago (MYA), represents the largest loss of marine and terrestrial diversity in the entire history of planet Earth. The initial extinction is thought to have been caused by the volcanic eruption of the Siberian Traps (a region of high-temperature basaltic lava flows that accumulated to form a plateau) in present-day Russia (see illustration). The eruptions are estimated to have released 3 × 10⁶ km³ (7.2 × 10⁵ mi³) of lava. Additional eruptions throughout the Early Triassic interval (that is, the interval of time following the Permian) are inferred from radiometric dating (a dating method that utilizes the decay of radioactive elements) of the Siberian Traps basalts and from rapid, global negative shifts in carbon isotopes (atoms having the same number of protons, but different numbers of neutrons). The initial and additional eruptive events resulted in extreme equatorial sea surface temperatures; these temperatures are hypothesized to have reached as high as 40°C (104°F), equivalent to the conditions in a hot tub. Increased ocean temperatures inhibit the dissolution of oxygen, while simultaneously slowing global ocean circulation, causing the deoxygenation of upwelling water masses and the surface ocean.

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