GSSP for Paibian Stage
Definition:
The base of the Paibian Stage and Furongian Series (= uppermost series of the Cambrian) is defined at 396 m in the Huaqiao Formation, Paibi section, NW Hunan Province, South China, coinciding with the lowest occurrence of the agnostoid trilobite Glyptagnostus reticulatus. This level is near the base of a large positive carbon-isotope excursion (SPICE excursion).
Location:
The Paibi Section is situated in the Wuling Mountains (Wulingshan), Huayuan County, NW Hunan Province, China at a latitude of 28°23.37' N and a longitude of 109°31.54' E of Greenwich. The Paibi section consists of a nearly continuous series of road cuts, small quarries, and hillside outcrops, located about 35km W of the city of Jishou along the north side of the Jishou-Huayuan highway (Chinese National Highway 319), and approximately 28km south of Huayuan. Beginning just west of the village of Sixin, the section extends approximately 1.7km to just west of the village of Paibi. The GSSP is represented on the Paibi topographic map Number H49 G 087025, 1:10,000 scale (Hunan Branch of State Topographical Surveying Bureau).
The GSSP occurs within the Huaqiao Formation, which consists of a thick succession of carbonate beds deposited in the outer part of the Jiangnan Slope Belt. The Huaqiao Formation at the Paibi section is mostly a succession of alternating thin-bedded, dark grey to black argillaceous- and lime-rich calcsiltites and calcilutites .
Primary Markers:
Trilobites:
The GSSP is defined at the lowest occurrence of the agnostoid trilobite Glyptagnostus reticulatus.
Secondary Markers:
Carbon Isotopes:
The FAD of Glyptagnostus reticulatus corresponds with the onset of a large positive shift in δ13C values referred to as the Steptoean positive carbon isotope excursion (SPICE excursion).
Correlation Events:
Trilobite FAD Glyptagnostus reticulatus
Other Locations around the World:
The First Occurrence of Glyptagnostus reticulatus is recognized worldwide.
Notes on Derivation of Age:
Radiometric ages near primary marker level. Estimated age and uncertainty only