Mundil Roland, Ludwig Kenneth R, Metcalfe Ian, Renne Paul R
Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA.
Science. 2004 Sep 17;305(5691):1760-3. doi: 10.1126/science.1101012.
The age and timing of the Permian-Triassic mass extinction have been difficult to determine because zircon populations from the type sections are typically affected by pervasive lead loss and contamination by indistinguishable older xenocrysts. Zircons from nine ash beds within the Shangsi and Meishan sections (China), pretreated by annealing followed by partial attack with hydrofluoric acid, result in suites of consistent and concordant uranium/lead (U/Pb) ages, eliminating the effects of lead loss. The U/Pb age of the main pulse of the extinction is 252.6 +/- 0.2 million years, synchronous with the Siberian flood volcanism, and it occurred within the quoted uncertainty.
二叠纪-三叠纪大灭绝的年代和时间一直难以确定，因为典型的标准剖面上的锆石群体通常受到普遍的铅损失以及无法区分的古老外来晶体的污染影响。对来自中国上寺和眉山剖面的九个灰层中的锆石进行预处理，先退火，然后用氢氟酸部分蚀刻，得到了一系列一致且协调的铀/铅（U/Pb）年龄，消除了铅损失的影响。灭绝主要脉冲的U/Pb年龄为2.526±0.02亿年，与西伯利亚洪流玄武岩活动同步，且发生在所述的不确定性范围内。
