A MINIMUM U-PB AGE FOR SIBERIAN FLOOD-BASALT VOLCANISM

摘要

Establishing an accurate and precise age for Siberian flood-basalt volcanism is of great importance in evaluating causes for the unequaled mass extinction of flora and fauna at the Permian-Triassic boundary. We report a new, minimum U-Pb age obtained from zircon and baddeleyite from the mineralized Noril'sk I intrusion that cuts the lower third of this rapidly deposited, 3500-m-thick volcanic sequence near Noril'sk. This 251.2 +/- 0.3 (2 sigma) Ma age is within analytical error of the SHRIMP U-Pb age for zircon from the Permian-Triassic boundary at Meishan, South China [251.1 +/- 3.6 Ma (2 sigma)], and confirms Siberian basaltic volcanism as a possible contributor to the mass extinction. [References: 54]