Cambrian Series 2

Last updated
Cambrian Series 2
~521 – ~509 Ma
Chronology
Etymology
Name formalityInformal
Usage information
Celestial body Earth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unit Epoch
Stratigraphic unit Series
Time span formalityFormal
Lower boundary definitionNot formally defined
Lower boundary definition candidates FAD of Trilobites
Lower boundary GSSP candidate section(s)None
Upper boundary definitionFAD of Oryctocephalus indicus .
Upper boundary GSSP Wuliu-Zengjiayan, Guizhou, China
26°04′51″N108°24′50″E / 26.0807°N 108.4138°E / 26.0807; 108.4138
Upper GSSP ratified2018 [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]

Contents

Naming

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

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

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 Ollenellidae 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]

Related Research Articles

<span class="mw-page-title-main">Cambrian</span> First period of the Paleozoic Era, 539–485 million years ago

The Cambrian is the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran period 538.8 million years ago (mya) to the beginning of the Ordovician period 485.4 mya. Its subdivisions, and its base, are somewhat in flux.

The PaleozoicEra is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six geologic periods :

The Lopingian is the uppermost series/last epoch of the Permian. It is the last epoch of the Paleozoic. The Lopingian was preceded by the Guadalupian and followed by the Early Triassic.

The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from 497 to 485.4 million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three stages: the Paibian, Jiangshanian and the unnamed 10th stage of the Cambrian.

The Paibian is the lowest stage of Furongian series of the Cambrian. It follows the Guzhangian and is succeeded by the Jiangshanian Stage. The base is defined as the first appearance of the trilobite Glyptagnostus reticulatus around 497 million years ago. The top, or the base of the Jiangshanian is defined as the first appearance of the trilobite Agnostotes orientalis around 494 million years ago.

The Kaili Formation(凯里組) is a stratigraphic formation which was deposited during the Lower and Middle Cambrian. The formation is approximately 200 metres (660 ft) thick and was named after the city Kaili in the Guizhou province of southwest China.

Lemdadella is an extinct genus of redlichiid trilobites that lived during the late Atdabanian stage, which lasted from 521 to 514 million years ago during the early part of the Cambrian Period.

<span class="mw-page-title-main">Terreneuvian</span> First epoch of the Cambrian Period

The Terreneuvian is the lowermost and oldest series of the Cambrian geological system. Its base is defined by the first appearance datum of the trace fossil Treptichnus pedum around 538.8 million years ago. Its top is defined as the first appearance of trilobites in the stratigraphic record around 521 million years ago. This series' name was formally accepted by the International Commission on Stratigraphy in 2007.

<span class="mw-page-title-main">Fortunian</span>

The Fortunian age marks the beginning of the Phanerozoic Eon, the Paleozoic Era, and the Cambrian Period. It is the first of the two stages of the Terreneuvian series. Its base is defined as the first appearance of the trace fossil Treptichnus pedum 538.8 million years ago. The top of the Fortunian which is the base of the Stage 2 of the Cambrian has not been formally defined yet, but will correspond to the appearance of an Archeocyatha species or "Small shelly fossils" approximately 529 million years ago.

Stage 2 of the Cambrian is the unnamed upper stage of the Terreneuvian Series. It lies atop the Fortunian and below Stage 3 of the Cambrian. It is commonly referred to as the Tommotian, after the Cambrian stratigraphy of Siberia. Neither the upper nor lower boundary has yet been defined by the International Commission on Stratigraphy. The preferred definitions for the lower boundary are the first appearance of the molluscs Watsonella crosbyi or Aldanella attleborensis around 529 million years ago. The correlation between the lowest occurrences of A. attleborensis and W. crosbyi with the Zhujiaqing positive carbon isotope excursion (ZHUCE) has led to the conclusion that the combination of these two markers are a reliable indicator of the boundary between the Fortunian and Stage 2. The proposed upper boundary might be the first appearance of trilobites around 521 million years ago.

The Jiangshanian is the middle stage of the Furongian series. It follows the Paibian Stage and is succeeded by the still unnamed Stage 10 of the Cambrian. The base is defined as the first appearance of the trilobite Agnostotes orientalis which is estimated to be 494 million years ago. The Jiangshanian lasted until approximately 489.5 million years ago.

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. The Guzhangian-Paibian boundary is marked by the first appearance of the trilobite Glyptagnostus reticulatus around 497 million years ago.

The Drumian is a stage of the Miaolingian Series of the Cambrian. It succeeds the Wuliuan and precedes the Guzhangian. The base is defined as the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago. The top is defined as the first appearance of another trilobite Lejopyge laevigata around 500.5 million years ago.

Oryctocephalus indicus is a species of corynexochid trilobite from the Cambrian. Its first appearance is proposed for the lower boundary of the Wuliuan, which corresponds to the beginning of the Miaolingian. The species was first described by the British paleontologist Frederick Richard Cowper Reed in 1910 as Zacanthoides indicus. It was transferred to the genus Oryctocephalus by the American paleontologist Charles Elmer Resser in 1938.

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 International Commission on Stratigraphy in 2018. 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.

Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite Lotagnostus americanus around 489.5 million years ago, but other fossils are also being discussed. The upper boundary is defined as the appearance of the conodont Iapetognathus fluctivagus which marks the beginning of the Tremadocian and is radiometrically dated as 485.4 million years ago.

<i>Lejopyge laevigata</i> Extinct species of trilobite

Lejopyge laevigata is a species of agnostid trilobite belonging to the genus Lejopyge. It existed during the Guzhangian to the Paibian Age of the Cambrian. It has a cosmopolitan distribution and is an important index fossil in biostratigraphy.

The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about 509 to 497 million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is preceded by the unnamed Cambrian Series 2 and succeeded by the Furongian series.

Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approximately to the first appearance of trilobites, about 521 million years ago, though the globally asynchronous appearance of trilobites warrants the use of a separate, globally synchronous marker to define the base. The upper boundary and beginning of Cambrian Stage 4 is informally defined as the first appearance of the trilobite genera Olenellus or Redlichia around 514 million years ago.

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. Both proposals will set the lower boundary close to 514 million years ago. The upper boundary corresponds to the beginning of the Wuliuan.

References

  1. ↑ "Chart/Time Scale". stratigraphy.org. International Commission on Stratigraphy.
  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. 1 2 3 "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. 1 2 "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. 1 2 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)
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