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A Marine Focus
Causes: Impact

Studies of the Permian Triassic Boundary (PTB) sites have shown that the extinctions contained therein occurred very quickly (Jin, 2000), consistent with extinction models for catastrophic extraterrestrial impacts. Fullerenes, containing Carbon isotopes ranging from C60 to C200, from sediments at PTB sites contain trapped helium and argon in isotopic ratios similar to the planetary component of carbonaceous chondrites. This data can be interpreted as indicating an extraterrestrial impact coincided with the end Permian extinction (Becker, 2001); however, there are several lines of evidence which contradict this theory. Although Becker et al. analyzed material from sections in Hungary, Japan, and China, the Hungarian section yielded no extraterrestrial signature, and their identification of the PTB in the Japanese section is questioned. (Farley, 2001)

Bolide Impact
Figure: Artist's rendition of a meteorite impact