Ar/[sup.39]Ar dates from the West Siberian Basin: Siberian flood basalt province doubled. (Reports)

Widespread basaltic volcanism occurred in the region of the West Siberian Basin in central Russia during Permo-Triassic times. New [sup.40]Ar/[sup.39]Ar age determinations on plagioclase grains from deep boreholes in the basin reveal that the basalts were erupted 249.4 ± 0.5 million years ago. This is synchronous with the bulk of the Siberian Traps, erupted further east on the Siberian Platform. The age and geochemical data confirm that the West Siberian Basin basalts are part of the Siberian Traps and at [east double the confirmed area of the volcanic province as a whole. The larger area of volcanism strengthens the link between the volcanism and the end-Permian mass extinction.
Basaltic magma that erupted simultaneously over large areas of Earth's surface--so-called flood basalts--may have released prodigious volumes of S[O.sub.2], C[O.sub.2], HF, and other gases; hence, it is argued, such an [...]