Tremadocian

Last updated
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]

In 2015, the Lawson Cove section in Millard County, Utah, was proposed as an Auxiliary boundary Stratotype Section and Point (ASSP) for the Tremadocian stage and Ordovician system. In addition to the first appearance datum of I. fluctivagus, fossils of olenid trilobite Jujuyaspis and planktonic graptolite Anisograptus matanensis are present in a nearby section. [10] In 2017, [11] the Xiaoyangqiao section near the Dayangcha Village, North China, was proposed as the second ASSP for the base of Tremadocian/Lower Ordovician. The first planktonic graptolites can be found right below the Cordylodus lindstromi Conodont Zone in this section. [12] Both ASSPs were approved through supermajority vote by the Subcommission on Ordovician Stratigraphy in 2016 and 2019, respectively. [13] However, in 2021, the International Union of Geological Sciences (IUGS) proposed to deny the use of specific points and replace them by Standard Auxiliary Boundary Stratotypes (SABS) for more "flexible" correlations with GSSPs. [13]

Regional stages

In North America the first stage of the Ordovician is the Gasconadian Stage. [14] In the Baltic region, the stages corresponding to Tremadocian are the Pakerort stage (lower) and the Varangu stage (upper). [15] [16]

Major events

The Cambrian-Tremadocian boundary is marked by the Cambrian-Ordovician extinction event. Overall the amount of biodiversity of the Cambrian was maintained. [17] 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. [18]

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. [19]

Several global events are observed in sediments of the Tremadocian age: the Acerocare Regressive Event, Black Mountain Transgressive Event (both in the Early Tremadocian), Peltocare Regressive Event, Kelly Creek Regressive Event, and Ceratopyge Regressive Event (the last two in the Late Tremadocian). [20] Lithological features of the Black Mountain event are observed in Australia and Gorny Altai, Russia. [20] The Ceratopyge Regressive Event records in Baltica at the end of the Apatokephalus serratus zone. Above the disappearance of Ceratopyge fauna, sediments are presented in a more depleted form due to the decreased sea level in the Late Tremadocian. [21]

The middle of the Tremadocian witnessed an extinction event known as the Mid-Tremadocian Extinction Event [22] or the Base Stairsian Mass Extinction Event, [23] which is particularly known to have affected Baltican conodonts. [22] This extinction event may have been caused by anoxia. [24] [25]

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. [26] 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). [27]

Ocean and climate

The Early Ordovician in general was a time of transgression. The climate was slowly cooling throughout the Ordovician. [28]

Related Research Articles

The Hirnantian is the final internationally recognized stage of the Ordovician Period of the Paleozoic Era. It was of short duration, lasting about 1.4 million years, from 445.2 to 443.8 Ma. The early part of the Hirnantian was characterized by cold temperatures, major glaciation, and a severe drop in sea level. In the latter part of the Hirnantian, temperatures rose, the glaciers melted, and sea level returned to the same or to a slightly higher level than it had been prior to the glaciation.

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.

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 Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species Undulograptus austrodentatus around 467.3 million years ago. It lasted for about 8.9 million years until the beginning of the Sandbian around 458.4 million years ago. This stage of the Ordovician was marked by the beginning of the Andean-Saharan glaciation.

In the geological timescale, the Llandovery Epoch occurred at the beginning of the Silurian Period. The Llandoverian Epoch follows the massive Ordovician-Silurian extinction events, which led to a large decrease in biodiversity and an opening up of ecosystems.

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.

<span class="mw-page-title-main">Green Point, Newfoundland and Labrador</span>

Green Point is located 12 km north of the town of Rocky Harbour in Gros Morne National Park, on the west coast of Newfoundland. It is the home to a small summer fishing community and a drive-in campground. In 2000, Green Point was designated the Global Stratotype Section and Point (GSSP) representing the division between the Cambrian and the Ordovician systems.

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

The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began 453 million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian 445.2 million years ago. During the Katian the climate cooled which started the Late Ordovician glaciation.

The Sandbian is the first stage of the Upper Ordovician. It follows the Darriwilian and is succeeded by the Katian. Its lower boundary is defined as the first appearance datum of the graptolite species Nemagraptus gracilis around 458.4 million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the Katian around 453 million years ago.

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.

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.

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.

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.

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.

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. ↑ James Frederick Miller, Kevin Ray Evans, Rahymond Lindsay Ethington, Rebecca L. Freeman, James Loch, John E. Repetski, Robert L. Ripperdan, John F. Taylor (2015). "Proposed Auxiliary Boundary Stratigraphic Section and Point (ASSP) for the base of the Ordovician System at Lawson Cove, Utah, USA". Stratigraphy. 12 (3): 219–236. doi:10.29041/strat.12.4.02.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ↑ Ian G. Percival (2017). "Ordovician News Number 35" (PDF). Subcommission on Ordovician Stratigraphy. p. 4. Archived (PDF) from the original on 2023-10-24.
  12. ↑ Xiaofeng Wang, Svend Stouge, Jörg Maletz, Gabriella Bagnoli, Yuping. Qi, Elena G. Raevskaya, Chuanshang Wang, Chunbo Yan (2021). "The Xiaoyangqiao section, Dayangcha, North China: the new global Auxiliary Boundary Stratotype Section and Point (ASSP) for the base of the Ordovician System". Episodes. 44 (4): 359–383. doi:10.18814/epiiugs/2020/020091. Archived from the original on 2022-12-01.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. 1 2 Martin J. Head, Marie-Pierre Aubry, Werner E. Piller, Mike Walker (2023). "The Standard Auxiliary Boundary Stratotype: a proposed replacement for the Auxiliary Stratotype Point in supporting a Global boundary Stratotype Section and Point (GSSP)" (PDF). Episodes. 46 (1): 35—45. doi:10.18814/epiiugs/2022/022012. Archived (PDF) from the original on 2024-02-02. Retrieved 2024-05-06.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ↑ "Kentucky Stratigraphy With Stage Correlations". University of Kentucky. Archived from the original on 2024-04-16.
  15. ↑ 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.
  16. ↑ "Ordovician of the Baltic". Paleobiology Database . Archived from the original on 2024-04-16. Retrieved 2024-04-20.
  17. ↑ 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.
  18. ↑ 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)
  19. ↑ 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)
  20. 1 2 N. V. Sennikov, O. T. Obut, E. V. Lykova, A. V. Timokhin, R. A. Khabibulina, T. A. Shcherbanenko (2021). "Event Stratigraphy and Correlation Problems of the Ordovician strata of Gorny Altai and Salair". Geodynamics & Tectonophysics (in Russian). 12 (2): 246—260. doi:10.5800/GT-2021-12-2-0523.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ↑ Frisk, Åsa (2004). "Trilobite biostratigraphy of the Tremadoc Bjørkåsholmen Formation on Öland, Sweden (WOGOGOB-2004 Conference materials)". Uppsala University. Archived from the original on 2024-05-06.
  22. 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.
  23. ↑ 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.
  24. ↑ 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.
  25. ↑ 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.
  26. ↑ 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)
  27. ↑ 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)
  28. ↑ 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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