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Eight new high-precision 206Pb/238U CA-IDTIMS ages from the Bowen Basin are integrated with previous CA-IDTIMS ages to further the calibration of Lopingian sequences that record a period of climatic change, extensive volcanism and mass extinction. Numerous tuffs occur within the late Permian as the basin develops and shifts towards increasingly terrestrial sedimentation and coal measures which record a series of super-eruptions spanning c. 2.5 million years between ∼254 and 252 Ma. One, the Yarrabee Tuff, represents a basin-wide event that has been used as a correlative surface, previously dated at a number of locations as 252.88 ± 0.07 Ma. These correspond to the Eastern Australia magmatic arc flare-up peaking at c. 253 Ma. A new CA-IDTIMS age is reported from the (upper) Black Alley Shale, at 257.8 ± 1.2 Ma (upper Black Alley). The Wuchiapingian-Changhsingian Boundary is in the lower Black Alley Shale. The Black Alley Shale/Peawaddy boundary is marked by the Micrhystridium evansii Acritarch Acme Zone and "Mantuan Productus Beds" here dated to c. 254.5 Ma (latest Wuchiapingian). This level and age may also mark the termination of the P4 glaciation of the Late Paleozoic Ice Age. Our Fort Cooper Coal age of 256.0 ± 1.4 Ma is consistent with ages from the Peawaddy and Tinowan formations. The Platypus Tuff, dated 256.58 ± 0.73 Ma, is another basin-wide marker of mid-Wuchiapingian age and represents a major super-volcanic event. The top of the Ingelara Formation is dated by our age of 257.33 ± 0.52 Ma. The Protohaploxypinus microcorpus and Playfordiaspora crenulata palynozones are of late Changhsingian age. The Permian-Triassic Boundary is placed in the lower Rewan Group and within the lower Lunatisporites pellucidus Zone.
Metcalfe et al. (Tue,) studied this question.