Permian radiolarian biostratigraphy
The Permian Period is one of the most varied times, not only in oceanic environments, but also for the evolution of the radiolarian assemblages. Permian radiolarians have been extensively studied, and great progress has been achieved recently in their biostratigraphy. Seventeen Permian radiolarian zones are summarized here. Among these, seven zones are assigned to the latest Carboniferous–early Permian, namely (in ascending order): the Pseudoalbaillella bulbosa Assemblage Zone, the Pseudoalbaillella u-forma–Pseudoalbaillella elegans Assemblage Zone, the Pseudoalbaillella lomentaria–Pseudoalbaillella sakmarensis Assemblage Zone, the Pseudoalbaillella rhombothoracata Interval Zone, the Albaillella xiaodongensis Assemblage Zone, the Albaillella sinuata Abundance Zone and the Pseudoalbaillella ishigai Abundance Zone. Five zones are attributed to the middle Permian, including the Pseudoalbaillella globosa Interval Zone, the Follicucullus monacanthus Interval Zone, the Follicucullus porrectus Interval Zone, the Follicucullus scholasticus Interval Zone and the Follicucullus charveti Interval Zone. Five zones belong to the middle Permian–late Permian, including the Albaillella cavitata Interval Zone, the Albaillella levis Interval Zone, the Albaillella excelsa Interval Zone, the Albaillella triangularis Interval Zone and the Albaillella yaoi Abundance Zone. These Permian radiolarian biozones and their correlations with conondont zones or other chronostratigraphic schemes are discussed. The phylogenetic model of radiolarians through the Permian Period is also revised.
Figures & Tables
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.