Guzhangian

28.7200°N 109.9647°E / 28.7200; 109.9647 The Guzhangian is an uppermost stage of the Miaolingian Series of the Cambrian. It follows the Drumian Stage and precedes the Paibian Stage of the Furongian Series. The base is defined as the first appearance of the trilobite Lejopyge laevigata around 500.5 million years ago.^[5] The Guzhangian-Paibian boundary is marked by the first appearance of the trilobite Glyptagnostus reticulatus around 497 million years ago.^[4]

Guzhangian
~500.5 – ~497 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
−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 Subdivision of the Cambrian according to the ICS, as of 2024.[1] Vertical axis scale: Millions of years ago
Etymology
Name formality	Formal
Name ratified	2008[2]
Former name(s)	Cambrian Stage 7
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	Shanchi et al., 2007[3]
Time span formality	Formal
Lower boundary definition	FAD of the Trilobite Lejopyge laevigata
Lower boundary GSSP	Luoyixi section, Luoyixi, Guzhang, Hunan, China 28.7200°N 109.9647°E / 28.7200; 109.9647
Lower GSSP ratified	2008[2]
Upper boundary definition	FAD of the Trilobite Glyptagnostus reticulatus
Upper boundary GSSP	Paibi section, Paibi, Hunan, China 28.3895°N 109.5257°E / 28.3895; 109.5257
Upper GSSP ratified	2003[4]

The name Guzhangian is derived from Guzhang County, Hunan Province, China.

GSSP

The GSSP is defined in the Huaqiao Formation in Hunan.^[2] The precise base of the Guzhangian is a limestone layer 121.3 m above the base Huaqiao Formation (花桥组) at the Louyixi section (28.7200°N 109.9647°E / 28.7200; 109.9647), where Lejopyge laevigata has its first appearance.^[5]

Paleogeography

It is assumed that in the Guzhangian the distance between the Earth and the Moon was 370,180 ± 1220 km (today, for comparison, it is 384,000 km). The length of an earthly day at that time was about 21.58 hours.^[6]

Major events

The species radiation occurred in the interval from the middle–late Drumian to middle Guzhangian. The extinction began in the middle of Guzhangian and lasted 3 million years until the middle of the Paibian age. As a result of this extinction, species diversity was reduced by 45%. Two phases of extinction can be traced in the sediments of South China: the first, with a slight decline in species, lasted about 1.8 million years; the second, with a sharper decline in richness, lasted 1.2 million years, more in the Paibian. After the extinction, species diversity returned to its previous level.^[7] From the Guzhangian to Jiangshanian, the oceans experienced a gradual depletion of oxygen, which affected bottom-dwelling inhabitants. This process and the SPICE event, associated with it, likely became the cause of the extinction.^[7]

References

1. "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. December 2024. Retrieved January 2, 2025.
2. Peng, Shanchi; Babcock, Loren; Zuo, Jingxun; Lin, Huanling; Zhu, Xuejian; Yang, Xianfeng; Robison, Richard; Qi, Yuping; Bagnoli, Gabriella; Chen, Yong’an (March 2009). "The Global Boundary Stratotype Section and Point (GSSP) of the Guzhangian Stage (Cambrian) in the Wuling Mountains, Northwestern Hunan, China" (PDF). Episodes. 32 (1): 41–55. doi:10.18814/epiiugs/2009/v32i1/006. Archived (PDF) from the original on 2023-06-20. Retrieved 2024-04-04.
3. Shanchi, Peng; Babcock, Loren; Jingxun, Zuo; Huanling, Lin; Xuejian, Zhu; Xianfeng, Yang; Robison, Richard; Yuping, Qi; Bagnoli, Gabriella; Yong’an, Chen. "PROPOSED GLOBAL STANDARD STRATOTYPE-SECTION AND POINT FOR THE GUZHANGIAN STAGE (CAMBRIAN)" (PDF). International Subcommission on Cretaceous Stratigraphy. International Subcommission on Cambrian Stratigraphy. Archived (PDF) from the original on 2016-04-08. Retrieved 2024-04-04.
4. Peng, S. C.; Babcock, L. E.; Robison, R. A.; Lin, H. L.; Rees, M. N.; Saltzman, M. R. (2004). "Global Standard Stratotype-Section and Point (GSSP) of the Furongian Series and Paibian Stage (Cambrian)" (PDF). Lethaia. 37 (4): 365–379. Bibcode:2004Letha..37..365P. doi:10.1080/00241160410002081. Archived (PDF) from the original on 2017-10-08. Retrieved 2024-04-04.
5. "GSSP for Guzhangian Stage". Archived from the original on 2023-01-24. Retrieved 2024-04-04.
6. Jichuang Fang, Fang Qiang, Shihong Zhang, Haiyan Li, Huaichun Wu, Meinan Shi, Tianshui Yang, Liwan Cao (2020). "Cyclostratigraphy of the global stratotype section and point (GSSP) of the basal Guzhangian Stage of the Cambrian Period". Palaeogeography, Palaeoclimatology, Palaeoecology. 540: 109530. Bibcode:2020PPP...54009530F. doi:10.1016/j.palaeo.2019.109530.{{cite journal}}: CS1 maint: multiple names: authors list (link)
7. Yiying Deng, Junxuan Fan, Shengchao Yang, Yukun Shi, Zhengbo Lu, Huiqing Xu, Zongyuan Sun, Fangqi Zhao, Zhangshuai Hou (2023). "No Furongian Biodiversity Gap: Evidence from South China". Palaeogeography, Palaeoclimatology, Palaeoecology. 618 (1): 111492. Bibcode:2023PPP...61811492D. doi:10.1016/j.palaeo.2023.111492.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links

• "Guzhangian Stage GSSP in the Luoyixi section, Hunan, China". timescalefoundation.org. Archived from the original on 2022-05-26.
• "GSSP Table - Paleozoic Era". Archived from the original on 2023-10-08.
• "GSSPs - The Cambrian System 2019". International Commission on Stratigraphy. Archived from the original on 2023-07-21.