Super-interesting news from Science express (abstract):
High-precision U-Pb daiting of several well preserved Permian-Triassic boundary sections in South China, by Shu-zhong Shen and colleagues, show that after a 2‰ in δ13C over 90.000 years the extinction peak occurred just before 252.28 ± 0,08 Ma. It coincided with a -5‰ δ13C excursion that is estimated to have lasted up to 20.000 years. According to this study the extinctions in the terrestrial and marine realms were synchronous, and the most probable cause was massive release of thermogenic carbon dioxide and/or methane. Contemporaneous charcoal and soot-bearing layers provide evidence of widespread wildfires on land.
The entire extinction interval was according to Shen et al. less than 200.000 years, by far the shortest duration calculated for the end-Permian event so far.