Wuliuan

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.[4] 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.[5]

Wuliuan
~509 – ~504.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
Key events in the Cambrian -540 — – -535 — – -530 — – -525 — – -520 — – -515 — – -510 — – -505 — – -500 — – -495 — – -490 — – -485 — – N ♇ P a l e o z o i c Ediacaran C a m b r i a n O T e r r e n e u v i a n S e r i e s 2 M i a o l i n g. F u r o n g. E Fortunian "Stage 2" "Stage 3" "Stage 4" Wuliuan Drumian Guzhangian Paibian Jiangshanian "Stage 10" Tremadocian                 ← Orsten Fauna ← Burgess Shale ← Kaili biota ← Archaeocyatha extinction ← Emu Bay Shale ← Sirius Passet biota ← Chengjiang biota ← First Trilobites ← SSF diversification, first brachiopods & archaeocyatha ← First halkieriids, mollusсs, hyoliths SSF ← Baykonurian glaciation ← Dresbachian extinction  Major Glacial period Stratigraphic scale of the ICS subdivisions and Precambrian/Cambrian boundary.
Etymology
Name formality	Formal
Name ratified	2018[1]
Former name(s)	Cambrian Stage 5
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
First proposed by	Zhao et. al, 2018[2]
Time span formality	Formal
Lower boundary definition	FAD of Oryctocephalus indicus.
Lower boundary GSSP	Wuliu-Zengjiayan, Guizhou, China 26.0807°N 108.4138°E
GSSP ratified	2018[1]
Upper boundary definition	FAD of the Trilobite Ptychagnostus atavus
Upper boundary GSSP	Drumian section, Wheeler Shale, Utah, U.S.A. 39.5117°N 112.9915°W
GSSP ratified	2006[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.[6]

GSSP

Three sections were discussed as GSSP candidates: the Wuliu-Zengjiayan section near Balang in Guizhou province (China), a section on Split Mountain in Nevada (USA)[5] and the "Molodo river section" along the Molodo river.[7] The Wuliu-Zengjiayan section is an outcrop of the Kaili Formation in the Wuliu quarry. The first candidate for the beginning of the Wuliuan was the trilobite Oryctocephalus indicus, the second candidate was the trilobite Ovatoryctocara granulata.[8]

The Wuliu-Zengjiayan section was chosen as the formal base in 2018, with the first appearance of Oryctocephalus indicus being chosen as the defining marker for the GSSP.[1]

References

1. Yuanlong Zhao; Jinliang Yuan; Loren E. Babcock; Qingjun Guo; Jin Peng; Leiming Yin; Xinglian Yang; Shanchi Peng; Chunjiang Wang; Robert R. Gaines; Jorge Esteve; Tongsu Tai; Ruidong Yang; Yue Wang; Haijing Sun; Yuning Yang (June 2019). "Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China" (PDF). Episodes. 42: 165–184. Retrieved 8 December 2020.
2. Yuanlong, Zhao; Jinliang, Yuan; Babcock, Loren; Qingjun, Guo; Jin, Peng; Leiming, Yin; Xinglian, Yang; Chunjiang, Wang; Gaines, Robert; Esteve, Jorge; Ruidong, Yang; Yuning, Yang; Haijing, Sun; Tongsu, Tai. "PROPOSED GLOBAL STANDARD STRATOTYPE-SECTION AND POINT FOR THE BASE OF THE MIAOLINGIAN SERIES AND WULIUAN STAGE （REPLACING PROVISIONAL CAMBRIAN SERIES 3 AND STAGE 5）". International Subcommission on Cretaceous Stratigraphy. International Subcommission on Cambrian Stratigraphy. Retrieved 13 December 2020.
3. Babcock, Loren; Robison, Richard; Rees, Margaret; Peng, Shanchi; Saltzman, Matthew (June 2007). "The Global boundary Stratotype Section and Point (GSSP) of the Drumian Stage (Cambrian) in the Drum Mountains, Utah, USA". Episodes. 30 (2): 85–89. doi:10.18814/epiiugs/2007/v30i2/003. Retrieved 13 December 2020.
4. "ChronostratChart2018-08" (PDF).
5. "GSSP Table - Paleozoic Era". Retrieved 15 November 2012.
6. "ISCS Annual Report 2017.pdf" (PDF).
7. "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group" (PDF). Episodes. 31 (4): 440–441.
8. 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.