Wuliuan
 | This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: The text below dates to before the formal definition of the stage. (July 2018) |
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−540 — – −535 — – −530 — – −525 — – −520 — – −515 — – −510 — – −505 — – −500 — – −495 — – −490 — – −485 — – | "Stage 2" "Stage 3" "Stage 4" "Stage 10" |
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The Wuliuan stage is the fifth stage of the Cambrian, and the first stage of the Miaolingian Series of the Cambrian. It was formally defined by the ICS in 2018.[2] Its base is defined by the first appearance of the trilobite species Oryctocephalus indicus; it ends with the beginning of the Drumian stage, marked by the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago.[3]
The 'golden spike' that formally defines the base of the period is driven into the Wuliu-Zengjiayan section of the Kaili formation, near Balang Village in the Miaoling Mountains, Guizhou, China.[4]
GSSP
Three sections are currently discussed as GSSP candidates: the Wuliu-Zengjiayan section near Balang in Guizhou province (China), a section on Split Mountain in Nevada (USA)[3] and the "Molodo river section" along the Molodo river.[5] The Wuliu-Zengjiayan section is an outcrop of the Kaili Formation in the Wuliu quarry. The first candidate for the beginning of Stage 5 is the trilobite Oryctocephalus indicus, the second candidate is the trilobite Ovatoryctocara granulata.[6]
References
- ^ "Chart/Time Scale". stratigraphy.org. International Commission on Stratigraphy.
- ^ "ChronostratChart2018-08" (PDF).
- ^ a b "GSSP Table - Paleozoic Era". Retrieved 15 November 2012.
- ^ "ISCS Annual Report 2017.pdf" (PDF).
- ^ "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group" (PDF). Episodes. 31 (4): 440–441.
- ^ Sundberg, F.A.; Zhao, Y.L.; Yuan, J.L.; Lin, J.P. (22 September 2011). "Detailed trilobite biostratigraphy across the proposed GSSP for Stage 5 ("Middle Cambrian" boundary) at the Wuliu-Zengjiayan section, Guizhou, China". Bulletin of Geosciences: 423–464. doi:10.3140/bull.geosci.1211.
