Multiple Stratigraphic Tools and Their Constraints on the End-Permian Mass Extinction and Collapse of Late Permian Marine Ecosystems: A Global View

An ever-expanding body of studies has revealed that the evolution of late Permian ecosystems was very complex and possibly involved some yet under-studied ‘early warning signals’ prior to the end-Permian mass extinction. However, the evidence in support of pre-extinction ‘warning signals’ is still limited. In a global review, this paper examined the timing for the initial and peak stages of the late Permian (including the Permian-Triassic boundary interval) biodiversity crisis across different palaeogeographic (palaeobathymetric) settings ranging from pelagic, deep-water basin/deep shelf, through moderately deep-water slope, and to shallow-water carbonate, reef and shallow shelf settings. Based on detailed correlations of globally significant Permian-Triassic sections (20 key sections reviewed) and key stratigraphic boundaries using bio-, chrono- and chemo-stratigraphy, this paper evaluated, summarized and compared the timing and pacing of the environmental and ecosystem deterioration processes in each and among the different palaeogeographic settings and between planktons (mainly radiolarians) and benthos (represented mainly by brachiopods and benthic foraminifers) in deep and moderately deep marine waters. Additionally, where data available we also reviewed the temporal evolution of redox conditions for 17 Permian-Triassic key sections in an attempt to ascertain if there were any notable temporal correlations between these two seemingly separate but potentially mechanistically linked processes. Finally, we also discussed the possible cause-effect and mutually amplifying relationships among volcanism, warming, dynamics of the oxygen minimum zone (OMZ), and the deterioration and final collapse of both marine and terrestrial ecosystems in the late Permian in the lead up to the end-Permian mass extinction.