Timing of recovery from the end-Permian extinction: Geochronologic and biostratigraphic constraints from south China
Four volcanic-ash beds bracket the Early-Middle Triassic boundary, as defined by conodont biostratigraphy, in a stratigraphic section in south China. High-precision U-Pb dates of single zircons allow us to place the Early to Middle Triassic (Olenekian-Anisian) boundary at 247.2 Ma. Magnetic-reversal stratigraphy allows global correlation. The new dates constrain the Early Triassic interval characterized by delayed biotic recovery and carbon-cycle instability to ∼5 m.y. This time constraint must be considered in any model for the end-Permian extinction and subsequent recovery.