Cambrian Stage 4

Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on Stratigraphy. One proposal is the first appearance of two trilobite genera, Olenellus or Redlichia. Another proposal is the first appearance of the trilobite species Arthricocephalus chauveaui.[1] Both proposals will set the lower boundary close to 514 million years ago.[2] The upper boundary corresponds to the beginning of the Wuliuan.

Key events in the Cambrian

-540 —

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-535 —

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-530 —

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-525 —

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-520 —

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-515 —

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-510 —

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-505 —

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-500 —

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-495 —

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-490 —

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-485 —

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N
P
Z

P
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Ediacaran

C
a
m
b
r
i
a
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Ordovician

T
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r
r
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v
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n

S
e
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2

M
i
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F
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Fortunian

"Stage 2"

"Stage 3"

"Stage 4"

←

Orsten Fauna

←

Burgess Shale

←

Kaili biota

←

Archaeocyatha extinction

←

Emu Bay Shale

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Sirius Passet biota

←

Chengjiang biota

←

First Trilobites

←

SSF diversification, first brachiopods & archaeocyatha

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First halkieriids, mollusсs, hyoliths SSF

←

Treptichnus pedum trace
Large negative peak δ 13C_carb excursion

←

Baykonurian glaciation

Major Glacial period

Stratigraphic scale of the ICS subdivisions and Precambrian/Cambrian boundary.

Naming

The International Commission on Stratigraphy has not named the fourth stage of the Cambrian yet. In the widely used Siberian nomenclature stage 4 would overlap with parts of the Botomian and Toyonian.[3]

Biostratigraphy

The beginning of Cambrian Stage 4 has been tentatively correlated with the base of the European Leonian faunal stage and the base of the South China Duyunian faunal stage.[4]

gollark: Write an abstractionoid™ for it.

gollark: I generally go for laziness and make the grid loop around.

gollark: The only real issue is boundary conditions.

gollark: Oh. Just… iterate over all the adjacent cells and add them?

gollark: Confusing how?

References

http://www.palaeontology.geo.uu.se/ISCS/ISCS_working_groups.html

Peng, S.C.; Babcock, L.E. (21 September 2011). "Continuing progress on chronostratigraphic subdivision of the Cambrian System" (PDF). Bulletin of Geosciences: 391–396. doi:10.3140/bull.geosci.1273. Retrieved 21 November 2012.
"GSSP Table - Paleozoic Era". Retrieved 18 November 2012.
"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 2012-11-21.
Yuan, Jinliang; Ng, Tin-Wai (2014). "Tentative correlation of the Duyunian (Cambrian Series 2, Stage 4) and the Taijiangian (Cambrian Series 3, Stage 5) between South China and the Mediterranean region". GFF. Geological Society of Sweden. 136 (1/2): 314–319. doi:10.1080/11035897.2014.898331.

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[Peng_2011-1] Peng, S.C.; Babcock, L.E. (21 September 2011). "Continuing progress on chronostratigraphic subdivision of the Cambrian System" (PDF). Bulletin of Geosciences: 391–396. doi:10.3140/bull.geosci.1273. Retrieved 21 November 2012.

[GSSP_Table_-_Paleozoic_Era-2] "GSSP Table - Paleozoic Era". Retrieved 18 November 2012.

[13th_conference-3] "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 2012-11-21.

[4] Yuan, Jinliang; Ng, Tin-Wai (2014). "Tentative correlation of the Duyunian (Cambrian Series 2, Stage 4) and the Taijiangian (Cambrian Series 3, Stage 5) between South China and the Mediterranean region". GFF. Geological Society of Sweden. 136 (1/2): 314–319. doi:10.1080/11035897.2014.898331.