Topic summary
Permian-Triassic mass extinction
Extracted from the Wikipedia article Permian–Triassic extinction event.
Dating
The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 million years ago, a duration of 60 ± 48 thousand years. A large, abrupt global decrease in δC, the ratio of the stable isotopecarbon-13 to that of carbon-12, coincides with this extinction, and is sometimes used to identify the Permian–Triassic boundary and the Permian-Triassic Mass Extinction event (PTME) in rocks that are unsuitable for radiometric dating. The negative carbon isotope excursion's magnitude was 4–7% and lasted for approximately 500,000 years, though estimating its exact value is challenging due to diagenetic alteration of many sedimentary facies spanning the boundary.