A global review of Permian macrofloral biostratigraphical schemes
Separate biostratigraphical schemes have been developed for Permian macrofloras in the five main phytochoria (palaeokingdoms), reflecting the essential lack of overlap in taxonomic composition. In Europe two biozones are normally recognized, in North America three zones, in Cathaysia three or four zones, in Gondwana four zones and in Angara five zones. The stratigraphical resolution tends to be far less than that of palynology, and up to an order of magnitude coarser than the macrofloral biozones of the Pennsylvanian subsystem. This is probably due, at least in part, to the lack of rigor in the way that the Permian macrofloral zones have been defined. Nevertheless, the existing zones do provide evidence of the overarching trajectory of change in vegetation through the Permian Period, as it responded at all palaeolatitudes to a combination of climate change, large-scale volcanic eruptions and tectonically driven landscape changes.
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The Palaeozoic Era ends with the c. 47-million-year-long Permian Period. This was a major juncture in Earth history when the vast Pangean supercontinent continued its assembly and the global biota suffered the most extensive biotic decimation of the Phanerozoic, the end-Permian mass extinction. It was also the time of accumulation of vast mineral and energy deposits, notably of salt and petroleum. The temporal ordering of geological and biotic events during Permian time is, therefore, critical to the interpretation of some unique and pivotal events in Earth history. This temporal ordering is based mostly on the Permian timescale, which has been developed and refined for nearly two centuries. This book reviews the history of the development of the Permian chronostratigraphic scale. It also includes comprehensive analyses of Permian radioisotopic ages, magnetostratigraphy, isotope-based correlations, and timescale-relevant marine and non-marine biostratigraphy and biochronology.