Tremadocian

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Tremadocian
485.4 ± 1.9 – 477.7 ± 1.4 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial body Earth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unit Age
Stratigraphic unit Stage
Time span formalityFormal
Lower boundary definition FAD of the Conodont Iapetognathus fluctivagus .
Lower boundary GSSPGreenpoint section, Green Point, Newfoundland, Canada
49°40′58″N57°57′55″W / 49.6829°N 57.9653°W / 49.6829; -57.9653
Lower GSSP ratified2000 [5]
Upper boundary definitionFAD of the Graptolite Tetragraptus approximatus
Upper boundary GSSP Diabasbrottet quarry, Västergötland, Sweden
58°21′32″N12°30′09″E / 58.3589°N 12.5024°E / 58.3589; 12.5024
Upper GSSP ratified2002 [6]
Rock from the Skiddaw Group, of Ordovician (Tremadocian) age, at Scawgill Bridge quarry in Cumbria, England, UK Rock of Skiddaw Group Scawgill.jpg
Rock from the Skiddaw Group, of Ordovician (Tremadocian) age, at Scawgill Bridge quarry in Cumbria, England, UK

The Tremadocian is the lowest stage of Ordovician. Together with the later Floian Stage it forms the Lower Ordovician Epoch. The Tremadocian lasted from 485.4 to 477.7 million years ago. The base of the Tremadocian is defined as the first appearance of the conodont species Iapetognathus fluctivagus at the Global Boundary Stratotype Section and Point (GSSP) section on Newfoundland. [7]

Contents

Naming

The Tremadocian is named after the village Tremadoc in Wales. The name was proposed by Adam Sedgwick in 1846 (as "Tremadoc group").

GSSP

The GSSP for the beginning of the Tremadocian is the Green Point section ( 49°40′58″N57°57′55″W / 49.6829°N 57.9653°W / 49.6829; -57.9653 ) [7] in Gros Morne National Park, in western Newfoundland. It is defined as the first appearance of the conodont species Iapetognathus fluctivagus . This horizon can be found 101.8 m above the Greenpoint section datum within bed number 23. [8] The boundary lies within the Broom Point Member, of the Green Point Formation which is part of the Cow Head Group. [5] The first planktonic graptolites appear 4.8 m above the first appearance of Iapetognathus fluctivagus at Greenpoint section. [5]

The Tremadocian ends with the beginning of the Floian which is defined as the first appearance of Tetragraptus approximatus at the GSSP in Diabasbrottet quarry, Västergötland, Sweden. [9]

Regional stages

In North America the first stage of the Ordovician is the Gasconadian Stage. [10] In Baltic region the stages corresponding to Tremadocian are Pakerort stage (older) and Varangu stage (younger). [11] [12]

Major events

The Cambrian-Tremadocian boundary is marked by the Cambrian-Ordovician extinction event. Overall the amount of biodiversity of the Cambrian was maintained. [13] At the beginning of the Tremadocian, about 485.4 million years ago, biodiversity, which had been at a low level, began its long increase phase, known as the Great Ordovician Biodiversification Event. [14]

At the Furongian‒Tremadocian boundary, a mantle plume event occurred on the territory of the northwestern Gondwana, which is now the Iberian Peninsula. Ollo de Sapo magmatic event continued in this region further into Ordovician. [15]

The middle of the Tremadocian witnessed an extinction event known as the Mid-Tremadocian Extinction Event [16] or the Base Stairsian Mass Extinction Event, [17] which is particularly known to have affected Baltican conodonts. [16] This extinction event may have been caused by anoxia. [18] [19]

Tremadocian life

Planktonic graptolites, an important index fossil, appear during the Tremadocian. [5] Tremadocian cephalopods were not very different from their Cambrian predecessors. Specimens of Ellesmeroceras and possibly Bassleroceras , found in Santa Rosita Formation, northwestern Argentina, show that cephalopods first migrated to the waters off western Gondwana already in the early Tremadocian. In the middle Tremadocian, cephalopods became more diverse and occupied new ecological niches. [20] During Tremadocian there was an exchange of fauna between Avalonia and Gondwana across the Rheic Ocean, as evidenced by the findings of morphologically similar trilobites of the genus Platypeltoides in Belgium, Wales (both were parts of Avalonia) and Morocco (Gondwana). [21]

Ocean and climate

The Early Ordovician in general was a time of transgression. The climate was slowly cooling throughout the Ordovician. [22]

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.

<span class="mw-page-title-main">Ordovician</span> Second period of the Paleozoic Era 485–444 million years ago

The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 Ma to the start of the Silurian Period 443.8 Ma.

<span class="mw-page-title-main">Silurian</span> Third period of the Paleozoic Era, 443–419 million years ago

The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.

First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particular species. A related term is last appearance datum (LAD), the last appearance of a species in the geologic record.

<span class="mw-page-title-main">Cambrian–Ordovician extinction event</span> Mass extinction event about 488 million years ago

The Cambrian–Ordovician extinction event, also known as the Cambrian-Ordovician boundary event, was an extinction event that occurred approximately 485 million years ago (mya) in the Paleozoic era of the early Phanerozoic eon. It was preceded by the less-documented End-Botomian mass extinction around 517 million years ago, and the Dresbachian extinction event about 502 million years ago.

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 Andean-Saharan glaciation, also known as the Early Paleozoic Ice Age (EPIA), the Early Paleozoic Icehouse, the Late Ordovician glaciation, the end-Ordovician glaciation, or the Hirnantian glaciation, occurred during the Paleozoic from approximately 460 Ma to around 420 Ma, during the Late Ordovician and the Silurian period. The major glaciation during this period was formerly thought only to consist of the Hirnantian glaciation itself but has now been recognized as a longer, more gradual event, which began as early as the Darriwilian, and possibly even the Floian. Evidence of this glaciation can be seen in places such as Arabia, North Africa, South Africa, Brazil, Peru, Bolivia, Chile, Argentina, and Wyoming. More evidence derived from isotopic data is that during the Late Ordovician, tropical ocean temperatures were about 5 °C cooler than present day; this would have been a major factor that aided in the glaciation process.

<span class="mw-page-title-main">Serpukhovian</span> Third stage of the Carboniferous

The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from 330.9 Ma to 323.2 Ma. It is preceded by the Visean and is followed by the Bashkirian. The Serpukhovian correlates with the lower part of the Namurian Stage of European stratigraphy and the middle and upper parts of the Chesterian Stage of North American stratigraphy.

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 Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from 477.7 to 470 million years ago. The lower boundary is defined as the first appearance of the graptolite species Tetragraptus approximatus.

The Great Ordovician Biodiversification Event (GOBE), was an evolutionary radiation of animal life throughout the Ordovician period, 40 million years after the Cambrian explosion, whereby the distinctive Cambrian fauna fizzled out to be replaced with a Paleozoic fauna rich in suspension feeder and pelagic animals.

The Dapingian is the third stage of the Ordovician period and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The top of the Floian is defined as the first appearance of the conodont species Baltoniodus triangularis which happened about 470 million years ago. The Dapingian lasted for about 2.7 million years until about 467.3 million years ago.

<span class="mw-page-title-main">Pridoli Epoch</span> Final Series (Epoch) of the Silurian

In the geologic timescale, the Přídolí Epoch is the uppermost subdivision of the Silurian Period, dated at between 423 ± 2.3 and 419.2 ± 3.2 mya. The Přídolí Epoch succeeds the Ludfordian Stage and precedes the Lochkovian, the lowest of three stages within the Lower Devonian geological epoch. It is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb, Slivenec, in the Czech Republic. The GSSP is located within the Požáry Formation, overlying the Kopanina Formation. Přídolí is the old name of a cadastral field area.

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.

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.

Iapetognathus fluctivagus is a species of denticulate cordylodan conodonts belonging to the genus Iapetognathus. It existed during the Tremadocian Age of the Ordovician. It is an important index fossil in biostratigraphy.

Iapetognathus is a genus of cordylodan conodonts. It is one of the oldest denticulate euconodont genera known.

Conodonts are an extinct class of animals whose feeding apparatuses called teeth or elements are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils in the subfield of the stratigraphy named biostratigraphy.

References

  1. ↑ Wellman, C.H.; Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B . 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC   1692785 . PMID   10905606.
  2. ↑ Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
  3. ↑ Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. doi:10.1038/ncomms14066. ISSN   2041-1723. PMC   5286199 . PMID   28117834. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
  4. ↑ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  5. 1 2 3 4 Cooper, Roger; Nowlan, Godfrey; Williams, S. H. (March 2001). "Global Stratotype Section and Point for base of the Ordovician System" (PDF). Episodes. 24 (1): 19–28. doi: 10.18814/epiiugs/2001/v24i1/005 . Archived (PDF) from the original on 2024-03-25. Retrieved 2024-04-15.
  6. ↑ Bergström, M.; Löfgren, Anita; Maletz, Jörg (December 2004). "The GSSP of the Second (Upper) Stage of the Lower Ordovician Series: Diabasbrottet at Hunneberg, Province of Västergötland, Southwestern Sweden" (PDF). Episodes. 27 (4): 265–272. doi: 10.18814/epiiugs/2004/v27i4/005 . Archived (PDF) from the original on 2023-06-20. Retrieved 2024-04-15.
  7. 1 2 "GSSP Table - Paleozoic Era". Archived from the original on 2023-10-08.
  8. ↑ "GSSP for Tremadocian Stage". timescalefoundation.org. Archived from the original on 2024-04-04.
  9. ↑ "GSSP for Floian Stage". timescalefoundation.org. Archived from the original on 2024-04-04.
  10. ↑ "Kentucky Stratigraphy With Stage Correlations". University of Kentucky. Archived from the original on 2024-04-16.
  11. ↑ Paškevičius, Juozas (2007). "Correlation of the Ordovician regional stages of the Baltic palaeobasin with new global stages" (PDF). Geologija (57): 30–36. ISSN   1392-110X. Archived (PDF) from the original on 2024-04-16.
  12. ↑ "Ordovician of the Baltic". Paleobiology Database . Archived from the original on 2024-04-16. Retrieved 2024-04-20.
  13. ↑ Sepkoski, J. J. (1995). "The Ordovician Radiations: Diversification and Extinction Shown by Global Genus-Level Taxonomic Data". pp. 393–396. Archived from the original on 2022-10-04. Retrieved 2024-04-20.
  14. ↑ 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. doi:10.1016/j.palaeo.2023.111492.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ↑ Josep Maria Casas, J. Brendan Murphy, Teresa Sanchez-Garcia, Jacques de Poulpiquet, José-Javier Alvaro, A. Díez-Montes, Joan Guimerà (2023). "Does the Ollo de Sapo magmatic event support Furongian-Tremadocian mantle plume activity fringing NW Gondwana?". International Geology Review. doi:10.1080/00206814.2023.2263787.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. 1 2 Stouge, Svend; Bagnoli, Gabriella; Rasmussen, Jan A. (1 July 2020). "Late Cambrian (Furongian) to mid-Ordovician euconodont events on Baltica: Invasions and immigrations". Palaeogeography, Palaeoclimatology, Palaeoecology . 549: 109151. doi:10.1016/j.palaeo.2019.04.007. S2CID   146630424 . Retrieved 2024-04-15.
  17. ↑ Lu, Xinze; Edwards, Cole T.; Kendall, Brian (15 January 2023). "No evidence for expansion of global ocean euxinia during the base Stairsian mass extinction event (Tremadocian, Early Ordovician)". Geochimica et Cosmochimica Acta . 341: 116–131. doi:10.1016/j.gca.2022.11.028. S2CID   254361718 . Retrieved 2024-04-15.
  18. ↑ Edwards, Cole T.; Fike, David A.; Saltzman, Matthew Ross; Lu, Wanyi; Lu, Zunli (1 January 2018). "Evidence for local and global redox conditions at an Early Ordovician (Tremadocian) mass extinction". Earth and Planetary Science Letters . 481: 125–135. doi: 10.1016/j.epsl.2017.10.002 . Retrieved 2024-04-15.
  19. ↑ Saltzman, Matthew Ross; Edwards, Cole T.; Adrain, Jonathan M.; Westrop, Stephen R. (1 September 2015). "Persistent oceanic anoxia and elevated extinction rates separate the Cambrian and Ordovician radiations". Geology . 43 (9): 807–810. doi:10.1130/G36814.1 . Retrieved 2024-04-15.
  20. ↑ Marcela Cichowolski, N. Emilio Vaccari, Alexander Pohle, Daniel Andres Morón-Alfonso, Romain Vaucher, Beatriz G. Waisfeld (2023). "Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America". Acta Palaeontologica Polonica. 68 (4): 583–601. doi:10.4202/app.01103.2023.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ↑ Lukáš Laibl, Thomas Servais, Bernard Mottequin (2023). "Tremadocian (Ordovician) trilobites from the Brabant Massif (Belgium): Palaeogeographical and palaeoecological implications". Geobios . 81: 7–16. doi:10.1016/j.geobios.2023.04.003.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  22. ↑ Munnecke, Axel; Calner, Mikael; Harper, David A.T.; Servais, Thomas (1 October 2010). "Ordovician and Silurian sea–water chemistry, sea level, and climate: A synopsis". Palaeogeography, Palaeoclimatology, Palaeoecology. 296 (3–4): 389–413. Bibcode:2010PPP...296..389M. doi:10.1016/j.palaeo.2010.08.001.
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