Cambrian Series 2

Unnamed 2nd series of the Cambrian

Cambrian Series 2

~521 – ~506.5 Ma

PreꞒ

A map of Earth 515 million years ago during the Cambrian's 2nd series, Stage 3

Chronology

−540 —

−535 —

−530 —

−525 —

−520 —

−515 —

−510 —

−505 —

−500 —

−495 —

−490 —

−485 —

Ediacaran

Early O

Fortunian

"Stage 2"

"Stage 3"

"Stage 4"

Wuliuan

Drumian

Guzhangian

Paibian

Jiangshanian

"Stage 10"

| | ←|

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| Informal
Usage information
Celestial body| Earth
Regional usage| Global (ICS)
Time scale(s) used| ICS Time Scale
Definition
Chronological unit| Epoch
Stratigraphic unit| Series
Time span formality| Formal
Lower boundary definition| Not formally defined
Lower boundary definition candidates| FAD of Trilobites
Lower boundary GSSP candidate section(s)| None
Upper boundary definition| FAD of Oryctocephalus indicus.
Upper boundary GSSP| Wuliu-Zengjiayan, Guizhou, China
26°04′51″N 108°24′50″E﻿ / ﻿26.0807°N 108.4138°E﻿ / 26.0807; 108.4138
Upper GSSP ratified| 2018[2]

Cambrian Series 2 is the unnamed 2nd series of the Cambrian. It lies above the Terreneuvian series and below the Miaolingian. Series 2 has not been formally defined by the International Commission on Stratigraphy, lacking a precise lower boundary and subdivision into stages. The proposed lower boundary is the first appearance of trilobites which is estimated to be around 521 million years ago.[3][4]

## Naming

[edit]

The International Commission on Stratigraphy has not named the 2nd series of the Cambrian yet.[3] In part the new name will replace the older terms "Lower Cambrian" and "Early Cambrian". The nomenclature used in Siberia uses the term "Yakutian" for this series.[5]

## Subdivisions

[edit]

The 2nd series is currently subdivided by the ICS into two stages: Cambrian Stage 3 and Cambrian Stage 4. Both of these stages also lack formal definition.[3] The Siberian nomenclature distinguishes three stages (lowest first): Atdabanian, Botomian and Toyonian.[5] In general most subdivisions of this series rely on biostratigraphy of trilobite zones.[6]

The Ordian stage, which is use in Australian chronostratigraphical scale, was originally supposed to be the lowest stage of the Miaolingian, but may belong to upper Series 2. As of 2024, the base of the Ordian is not defined yet.[7]

## Biostratigraphy

[edit]

The beginning of the 2nd series of the Cambrian is marked by the appearance of trilobites. Correlating this event on different continents has proven difficult and resolving this is essential for the definition of the lower boundary of this series. Currently the oldest trilobite known is Lemdadella which marks the beginning of the Fallotaspis zone.[6]

The end of the 2nd series of the Cambrian is marked by the first major biotic extinction of the Paleozoic. Changes in ocean chemistry and the marine environment are posited as the most likely cause of this extinction.[8] At the Series 2–Miaolingian boundary, the first major trilobite extinction, known as the Olenellid Biomere boundary, occurred. In particular, trilobites of the families Olenellidae and Redlichiidae have been extinct in Laurentia and South China, respectively.[9] The first O. indicus appear after this global extinction, and in areas where O. indicus fossils are absent, the Series 2–Miaolingian boundary is determined by chemostratigraphic data.[10]

## References

[edit]

1. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. December 2024. Retrieved January 2, 2025.
2. ^ Zhao; et al. (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\. Archived (PDF) from the original on 2022-03-04. Retrieved 2024-04-02.
3. ^ a b c "GSSP Table - Paleozoic Era". Archived from the original on 2023-10-08. Retrieved 2024-04-02.
4. ^ Wu, Tong; Yang, Ruidong; Gao, Junbo; Li, Jun (1 January 2021). "Age of the lower Cambrian Vanadium deposit, East Guizhou, South China: Evidences from age of tuff and carbon isotope analysis along the Bagong section". Open Geosciences. 13 (1): 999–1012\. doi:10.1515/geo-2020-0287. ISSN 2391-5447.
5. ^ a b "The 13th International Field Conference of the Cambrian Stage Subdivision Working Group" (PDF). Episodes. 31 (4): 440–441\. Archived from the original (PDF) on 2014-11-05. Retrieved 2024-04-02.
6. ^ a b Yuan, J.L.; Zhu, X.J.; Lin, J.P.; Zhu, M.Y. (22 September 2011). "Tentative correlation of Cambrian Series 2 between South China and other continents" (PDF). Bulletin of Geosciences: 397–404\. doi:10.3140/bull.geosci.1274. Archived from the original (PDF) on 2024-01-18. Retrieved 2024-04-02.
7. ^ John R. Laurie, Peter D. Kruse, Glenn A. Brock, James D. Holmes, James B. Jago, Marissa J. Betts, John R. Paterson, Patrick M. Smith (April 2024). "The quest for an Australian Cambrian stage scale". Alcheringa: An Australasian Journal of Palaeontology. doi:10.1080/03115518.2024.2327045.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
8. ^ Zhang, Wenhao; et al. (2014). "Mass-occurrence of oncoids at the Cambrian Series 2–Series 3 transition: Implications for microbial resurgence following an Early Cambrian extinction". Gondwana Research. 28: 432–450\. doi:10.1016/j.gr.2014.03.015.
9. ^ Jih-Pai Lin, Frederick A. Sundberg, Ganqing Jiang, Isabel P. Montañez, Thomas Wotte (22 November 2019). "Chemostratigraphic correlations across the first major trilobite extinction and faunal turnovers between Laurentia and South China". Scientific Reports. 9 (1): 17392. doi:10.1038/s41598-019-53685-2. PMC 6874646.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
10. ^ Courtney Birksmith, Glenn A. Brock, Marissa J. Betts, James D. Holmes, Zhiliang Zhang (2023). "Chronostratigraphy of the Cambrian Series 2 -Miaolingian boundary, western Stansbury Basin, South Australia". Conference: Palaeo Down Under 3 at Perth, Western Australia.`{{cite web}}`: CS1 maint: multiple names: authors list (link)

## External links

[edit]

* "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.

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Cambrian Period

| Terreneuvian| Series 2| Miaolingian| Furongian

|
|
|

* Fortunian
* Stage 2

* Stage 3
* Stage 4

* Wuliuan
* Drumian
* Guzhangian

* Paibian
* Jiangshanian
* Stage 10

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* t
* e

Geological history of Earth

Cenozoic Era
(present–66.0 Ma)|

| Quaternary (present–2.58 Ma)|

* Holocene (present–11.7 ka)
* Pleistocene (11.7 ka–2.58 Ma)

|

Neogene (2.58–23.0 Ma)|

* Pliocene (2.59–5.33 Ma)
* Miocene (5.33–23.0 Ma)

Paleogene (23.0–66.0 Ma)|

* Oligocene (23.0–33.9 Ma)
* Eocene (33.9–56.0 Ma)
* Paleocene (56.0–66.0 Ma)

Mesozoic Era
(66.0–252 Ma)|

| Cretaceous (66.0–145 Ma)|

* Late (66.0–100 Ma)
* Early (100–145 Ma)

|

Jurassic (145–201 Ma)|

* Late (145–164 Ma)
* Middle (164–174 Ma)
* Early (174–201 Ma)

Triassic (201–252 Ma)|

* Late (201–237 Ma)
* Middle (237–247 Ma)
* Early (247–252 Ma)

Paleozoic Era
(252–539 Ma)|

| Permian (252–299 Ma)|

* Lopingian (252–260 Ma)
* Guadalupian (260–272 Ma)
* Cisuralian (272–299 Ma)

|

Carboniferous (299–359 Ma)|

* Pennsylvanian (299–323 Ma)
* Mississippian (323–359 Ma)

Devonian (359–419 Ma)|

* Late (359–383 Ma)
* Middle (383–393 Ma)
* Early (393–419 Ma)

Silurian (419–444 Ma)|

* Pridoli (419–423 Ma)
* Ludlow (423–427 Ma)
* Wenlock (427–433 Ma)
* Llandovery (433–444 Ma)

Ordovician (444–485 Ma)|

* Late (444–458 Ma)
* Middle (458–470 Ma)
* Early (470–485 Ma)

Cambrian (485–539 Ma)|

* Furongian (485–497 Ma)
* Miaolingian (497–509 Ma)
* Series 2 (509–521 Ma)
* Terreneuvian (521–539 Ma)

Proterozoic Eon
(539 Ma–2.5 Ga)|

| Neoproterozoic (539 Ma–1 Ga)|

* Ediacaran (539–635 Ma)
* Cryogenian (635–720 Ma)
* Tonian (720 Ma–1 Ga)

|

Mesoproterozoic (1–1.6 Ga)|

* Stenian (1–1.2 Ga)
* Ectasian (1.2–1.4 Ga)
* Calymmian (1.4–1.6 Ga)

Paleoproterozoic (1.6–2.5 Ga)|

* Statherian (1.6–1.8 Ga)
* Orosirian (1.8–2.05 Ga)
* Rhyacian (2.05–2.3 Ga)
* Siderian (2.3–2.5 Ga)

Archean Eon (2.5–4 Ga)|

* Neoarchean (2.5–2.8 Ga)
* Mesoarchean (2.8–3.2 Ga)
* Paleoarchean (3.2–3.6 Ga)
* Eoarchean (3.6–4 Ga)

Hadean Eon (4–4.6 Ga)|

ka = kiloannum (thousand years ago); Ma = megaannum (million years ago); Ga = gigaannum (billion years ago).
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