The Permian Timescale

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.
The Permian timescale: an introduction
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Published:January 01, 2018
Abstract:
The Permian timescale has developed over about two centuries of research to the current chronostratigraphic scale advocated by the Subcommission on Permian Stratigraphy of three series and nine stages: Cisuralian (lower Permian) – Asselian, Sakmarian, Artinskian, Kungurian; Guadalupian (middle Permian) – Roadian, Wordian, Capitanian; and Lopingian (upper Permian) – Wuchiapingian and Changhsingian. The boundaries of the Permian System are defined by global stratotype sections and points (GSSPs) and the numerical ages of those boundaries appear to be determined with a precision better than 1‰. Nevertheless, much work remains to be done to refine the Permian timescale. Precise numerical age control within the Permian is very uneven and a global polarity timescale for the Permian is far from established. Chronostratigraphic definitions of three of the nine Permian stages remain unfinished and various issues of marine biostratigraphy are still unresolved. In the non-marine Permian realm, much progress has been made in correlation, especially using palynomorphs, megafossil plants, conchostracans and both the footprints and bones of tetrapods (amphibians and reptiles), but many problems of correlation remain, especially the cross-correlation of non-marine and marine chronologies. The further development of a Permian chronostratigraphic scale faces various problems, including those of stability and priority of nomenclature and concepts, disagreements over changing taxonomy, ammonoid v. fusulinid v. conodont biostratigraphy, differences in the perceived significance of biotic events for chronostratigraphic classification and correlation problems between provinces. Future research on the Permian timescale should focus on GSSP selection for the remaining undefined stage bases, the definition and characterization of substages, and further development and integration of the Permian chronostratigraphic scale with radioisotopic, magnetostratigraphic and chemostratigraphic tools for calibration and correlation.
- absolute age
- alkaline earth metals
- Ammonoidea
- Anthozoa
- Arthropoda
- biostratigraphy
- Brachiopoda
- Branchiopoda
- C-13/C-12
- carbon
- Cephalopoda
- chemostratigraphy
- Chordata
- chronostratigraphy
- Cnidaria
- Conodonta
- Crustacea
- depositional environment
- Foraminifera
- fossils
- Fusulinidae
- Fusulinina
- historical geology
- isotope ratios
- isotopes
- magnetostratigraphy
- Mandibulata
- marine environment
- metals
- microfossils
- Mollusca
- paleontology
- Paleozoic
- palynomorphs
- Permian
- Plantae
- radioactive isotopes
- Radiolaria
- Rugosa
- Sr-87/Sr-86
- stable isotopes
- stratigraphic units
- stratigraphy
- strontium
- terrestrial environment
- Tetrapoda
- time scales
- tracks
- Vertebrata
- Zoantharia