Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China

Abstract

The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point (GSSP) defining the conterminous base of the third series and the fifth stage of the Cambrian System. The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage, after the Maioling Mountains in southeastern Guizhou and the Wuliu sidehill, Jianhe County, in eastern Guizhou Province, South China, where the GSSP is located. The GSSP is exposed in a natural outcrop near the Balang Village at a position of 26° 44.843′N latitude and 108° 24.830′E longitude. It is defined at the base of a silty mudstone layer 52.8 m above the base of the Kaili Formation in the Wuliu-Zengjiayan section, coinciding with the first appearance of the cosmopolitan oryctocephalid trilobite Oryctocephalus indicus (base of the O. indicus Zone). Secondary global markers at or near the base of the series and stage include the peak of a rather large negative carbon isotopic excursion (ROECE excursion), the simultaneous appearance of many acanthomorphic acritarch forms, a transgressive phase of a major eustatic event, and the last appearance of intercontinental polymerid trilobites, either Bathynotus or Ovatoryctocara. Faunal turnovers close to the base of the Miaolingian Series and Wuliuan Stage have been recognized as being at the base of the Oryctocephalus indicus Zone of Amgan Stage in Siberia, the Delamaran Stage in Laurentia, the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland, near the base of the Delamaran Stage in Australia, and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco.