title: Age and timing of the Permian mass extinctions: U/Pb dating of closed-system zircons.
abstract: 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.
authors.affiliation: Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Mundil
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Ludwig
authors.forename: Ian
authors.initials: I
authors.lastname: Metcalfe
authors.forename: Paul R
authors.initials: PR
authors.lastname: Renne
mesh_terms: D000818:Animals; D002681:China; D005580:Fossils; D019015:Geologic Sediments; D005844:Geology / Q000379:methods*; D007854:Lead / Q000032:analysis*; D011156:Population Density; D011157:Population Dynamics; D017640:Silicates / Q000737:chemistry*; D013995:Time; D014501:Uranium / Q000032:analysis*; D018707:Volcanic Eruptions; D015040:Zirconium / Q000737:chemistry*
chemical_list: D017640:Silicates; D007854:Lead; D014501:Uranium; C003784:zircon; D015040:Zirconium