Environmental change in the late Permian of Queensland, NE Australia: The warmup to the end-Permian Extinction

The upper part of the Permian succession in Bowen Basin Queensland, NE Australia, was investigated to ascertain timeline and character environmental changes this high southern palaeolatitudinal setting leading up End-Permian Extinction (EPE). study focused on (in ascending order) Peawaddy Formation, Black Alley Shale, Bandanna laterally correlative units. In western Basin, base Formation (257 Ma) records onset thrust loading volcanic activity associated with Hunter-Bowen contractional orogeny. comprises a series coarsening-upward, terrigenous clastic intervals interpreted as product repeated progradation deltas into shallow, open marine environments. overlying Shale also multiple deltaic coarsening-upward cycles, which accumulated stressed, restricted uppermost equivalents formed extensive coastal plain estuarine All three formations under influence explosive from emerging continental arc east foreland basin. Volcanism peaked during deposition around Wuchiapingian–Changhsingian transition. Abundant dispersed gravel glendonites (calcite pseudomorphs after ikaite) indicate that cold conditions possible glacial ice (P4 Glaciation; Wuchiapingian Stage). Direct evidence ends at top (254.5 Ma); however, Chemical Index Alteration (CIA) data suggest surface remained through accumulation lower until c. 253 Ma, before gradually rising Formation. end P4 glaciation is characterized by major spike abundance acritarchs ( Micrhystridium evansii Acme Zone), reflecting development regional basin elevated nutrient concentrations but reduced salinity. contrast short interval stressed conditions, fossil floras remarkably consistent terrestrial ecosystems throughout late Lopingian EPE. EPE recorded distinctive, laminated mudrock bed (‘Marker Mudstone’) palynological ‘dead zone’ above coal seam or equivalent root-penetrated horizon followed spikes non-marine algal abundance. Overall, time 257–252 Ma represented studied does not record simple monotonic change palaeoenvironmental rather intermittent stepwise towards warmer, more environmentally eastern Australia. • (257–251.9 northeastern Several are recorded, Glaciation lasted 254.5 climate persisted Major bloom restriction circulation occurred Climate warmed end-Permian, flora stable abrupt collapse 252