Dapingian

The Ordovician was divided into three series and six global stages in 1995. Although at the time of 2005 GSSPs for the overlying Darriwilian and underlying "second stage" had already been ratified, definition of a GSSP for the first stage of the Middle Ordovician Series caused difficulties due to the deficiencies of the selected biohorizon and section.{{Cite journal |last=Finney |first=S. |date=2005 |title=Global Series and Stages for the Ordovician System: A Progress Report |url=https://www.researchgate.net/publication/39120677 |journal=Geologica Acta |volume=3 |issue=4 |pages=309–316 |doi=10.1344/104.000001381|doi-broken-date=12 June 2025 }} The Dapingian was the last Ordovician stage to be ratified, and was initially referred to as an informal and unnamed "third stage" corresponding to the early part of the Middle Ordovician. This third stage was meant to represent the appearance of several major index fossils. The conodont Baltoniodus triangularis, a species found in Baltica and China, defined the base of the regional Baltoscandian Volkhov stage. Another conodont, Tripodus laevis, defined the base of the Whiterockian stage in western North America. T. laevis was also roughly correlated with the appearance of the graptolite Isograptus v. lunatus.{{cite journal |last=Wang |first=Xiaofeng |author2=Stouge, Svend |author3=Erdtmann, Bernd-D. |author4=Chen, Xiaohong |author5=Li, Zhihong |author6=Wang, Chuanshang |author7=Zeng, Qingluan |author8=Zhou, Zhiqiang |author9= Chen, Huiming |title=A proposed GSSP for the base of the Middle Ordovician Series: the Huanghuachang section, Yichang, China |journal=Episodes |year=2005 |volume=28 |issue=2 |pages=105–117 |doi=10.18814/epiiugs/2005/v28i2/004 |url=https://timescalefoundation.org/references/Dapingian.pdf|accessdate=2024-06-30|doi-access=free|archive-url=https://web.archive.org/web/20240615153751/https://timescalefoundation.org/references/Dapingian.pdf|archive-date=2024-06-15|url-status=live}}

The Whiterock Narrows section in the Ninemile Formation of Nevada was the initial suggestion for the GSSP of the third stage, but a 2001 review of the site revealed that its local conodont fauna was misaligned with wider graptolite zonation. In its place, two formal GSSP candidates were proposed. The Niquivil section of Argentina used another widespread species, Protoprioniodus (Cooperignathus) aranda, as a proxy for B. triangularis, T. laevis, and graptolites, which were absent from the section.{{Cite journal |last1=Albanesi |first1=Guillermo L. |last2=Carrera |first2=Marcelo G. |last3=Cañas |first3=Fernando L. |last4=Saltzman |first4=Matthew |date=2006-03-01 |title=A proposed Global Boundary Stratotype Section and Point for the base of the Middle Ordovician Series: The Niquivil section, Precordillera of San Juan, Argentina |journal=Episodes |volume=29 |issue=1 |pages=1–15 |doi=10.18814/epiiugs/2006/v29i1/001 |s2cid=128233348 |issn=0705-3797|doi-access=free }} The Huanghuachang section of China hosted a more diverse fauna of index fossils, including Baltoniodus triangularis and biostratigraphically useful graptolites and chitinozoans. The Huanghuachang section was approved as the GSSP for the third stage in 2006, and was ratified by the ICS in 2007.{{Cite journal |last1=Wang |first1=Xiaofeng |last2=Stouge |first2=Svend |last3=Chen |first3=Xiaohong |last4=Li |first4=Zhihong |last5=Wang |first5=Chuanshang |date=2009 |title=Dapingian Stage: standard name for the lowermost global stage of the Middle Ordovician Series |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1502-3931.2009.00169.x |journal=Lethaia |language=en |volume=42 |issue=3 |pages=377–380 |doi=10.1111/j.1502-3931.2009.00169.x|bibcode=2009Letha..42..377W |url-access=subscription }}

The Dapingian is named after Daping, a village that lies near the Dapingian GSSP at Huanghuachang. The Chenjiahe section, an outcrop with similar rocks, can be found 5 km to the north of the Huanghuachang section. The name of the Dapingian stage was introduced in June 2007 and approved alongside the stage's ratification, beating out earlier suggestions such as "Volkhovian" and "Huanghuachangian".

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The Global Boundary Stratotype Section and Point (GSSP) of the Dapingian is the Huanghuachang section ({{Coord|30.8605|N|110.3740|E|display=inline}}), in Huanghuachang, Yichang, China. It is an outcrop of the Dawan Formation. The lower boundary is defined as the first appearance of the conodont species Baltoniodus triangularis in the type section. Radiometric dating has constrained the Floian-Dapingian boundary at {{Period start|Dapingian}} million years ago. The exact boundary lies 10.57 m above the base of Dawan Formation.{{cite journal |last=Wang |first=Xiaofeng |author2=Stouge, Svend |author3=Xiaohong, Chen |author4=Zhihong, Li |author5=Chuanshang, Wang |author6=Finney, Stan C. |author7=Qingluan, Zeng |author8=Zhiqiang, Zhou |author9=Huiming, Chen |author10= Erdtmann, Bernd-D. |title=The Global Stratotype Section and Point for the base of the Middle Ordovician Series and the Third Stage (Dapingian) |journal=Episodes |year=2009 |volume=32 |issue=2 |pages=96–113 |doi=10.18814/epiiugs/2009/v32i2/003 |s2cid=43893965 |url=https://timescalefoundation.org/references/Dapingian_v32n20.pdf|accessdate=2024-06-30|doi-access=free|archive-url=https://web.archive.org/web/20240301215239/https://timescalefoundation.org/references/Dapingian_v32n20.pdf|archive-date=2024-03-01|url-status=live}}

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The Dapingian overlaps with the upper part of the Arenig, a geologic stage used in England.{{cite book |title=The Geologic Time Scale 2012 |year=2012 |publisher=Elsevier Science Ltd. |isbn=978-0444594259 |url=https://books.google.com/books?id=usoqlA8AVDUC&q=542 |editor=Gradstein, F. M. |page=504 }} It is also equivalent to the lower part of the North American Whiterockian stage,{{cite web|url=https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1208&context=kgs_mc|title=Kentucky Stratigraphy With Stage Correlations|publisher=University of Kentucky|archive-url=https://web.archive.org/web/20240416105805/https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1208&context=kgs_mc|archive-date=2024-04-16|url-status=live}} most of the Baltic/Russian Volkhov stage,{{cite journal|author=Hansen, T.|date=2010-02-16|url=https://2dgf.dk/xpdf/bull58-1-13.pdf|title=Cyrtometopinid trilobites from the upper Volkhov and lower Lynna Formation (lower Darriwilian) of NW Russia|journal=Bulletin of the Geological Society of Denmark|volume=58|pages=1–13|issn=0011-6297|doi=10.37570/bgsd-2010-58-01|bibcode=2010BuGSD..58....1H |archive-url=https://web.archive.org/web/20160620164801/http://2dgf.dk/xpdf/bull58-1-13.pdf|archive-date=2016-06-20|url-status=live}}{{cite journal|author=Sergey Rozhnov|year=2017|url=https://www.researchgate.net/publication/321026991|title=Cyanobacterial origin and morphology of the volkhov hardgrounds (Dapingian, middle ordovician) of the St. Petersburg region (Russia)|journal=Bollettino della Società Paleontologica Italiana|volume=56|issue=2|pages=153–160|doi=10.4435/BSPI.2017.18|doi-broken-date=2024-11-20 }} and the Castlemainian and Yapeenian stages which have been used in Australia.{{cite journal|author1=Stig M. Bergström|author2=Xu Chen|author3=Juan Carlos Gutiérrez-Marco|author4=Andrei Dronov|year=2009|url=|title=The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ13C chemostratigraphy|journal=Lethaia|volume=42|issue=1|pages=97–107|doi=10.1111/j.1502-3931.2008.00136.x|doi-access=free|bibcode=2009Letha..42...97B |language=en}} In Baltoscandia, especially in the East Baltic, the global stage boundary corresponds to the bases of the Megistaspis polyphemus Trilobite Zone and probably Isograptus victoriae victoriae Graptolite Zone.{{cite journal|author1=Stig M. Bergström|author2=Anita M. Lofgren|date=December 2008|url=https://www.researchgate.net/publication/231930918|title=The base of the global Dapingian Stage (Ordovician) in Baltoscandia: Conodonts, graptolites and unconformities|journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh|volume=99|issue=3–4|pages=189–212|doi=10.1017/S1755691009008081|bibcode=2008EESTR..99..189B }}

At the beginning of the Dapingian, there was a drop in sea level of 70–80 m, which is reflected in the rocks as a well-developed hardground surface in Baltoscandia. Changes in sea level during Dapingian age appear to be associated with short pulses of cooling, which have become a harbinger of much colder climate in the next Darriwilian age.{{cite journal|author1=Rasmussen, J. A.|author2=Thibault, N.|author3=Mac Ørum Rasmussen, C.|date=November 5, 2021|url=|title=Middle Ordovician astrochronology decouples asteroid breakup from glacially-induced biotic radiations|journal=Nature|volume=12|issue=6430|page=6430 |doi=10.1038/s41467-021-26396-4|doi-access=free|pmid=34741034 |pmc=8571325|bibcode=2021NatCo..12.6430R }} At the end of the Dapingian, continental ice was growing with small changes in volume caused by changes in the Earth's orbit.{{cite journal|author1=Oluwaseun Edward|author2=Christoph Korte|author3=Clemens V. Ullmann|author4=Jorge Colmenar|author5=Nicolas Thibault|author6=Gabriella Bagnoli|author7=Svend Stouge|author8=Christian M. Ø. Rasmussen|date=February 22, 2022|url=|title=A Baltic Perspective on the Early to Early Late Ordovician δ13C and δ18O Records and Its Paleoenvironmental Significance|journal=Paleoceanography and Paleoclimatology|volume=37|issue=3|pages=1–26|doi=10.1029/2021PA004309|doi-access=free|bibcode=2022PaPa...37.4309E }}

The Great Ordovician Biodiversification Event (GOBE) lasted in the Dapingian. Fan et al. (2020) define GOBE as a 20 Myr interval that began in the Tremadocian and ended in the late Dapingian, although other researchers have suggested different temporal limits.{{cite journal|author1=L. Robin M. Cocks|author2=Trond H. Torsvik|date=December 2021|title=Ordovician palaeogeography and climate change|journal=Gondwana Research|volume=100|issue=|pages=53–72|doi=10.1016/j.gr.2020.09.008|doi-access=free|bibcode=2021GondR.100...53C |language=en|hdl=10852/83447|hdl-access=free}}

The extensive transgression associated with rapid tectonic subsidence, occurred at the end of the Dapingian in the Southern Urals.{{cite journal|author1=T. M. Mavrinskaya|author2=R. R. Yakupov|year=2014|url=http://ig.ufaras.ru/File/E2014/05_01_14.pdf#page=5|title=Biofacial analysis of Ordovician basin on western slope of the South Urals|journal=Геологический сборник|volume=11|page=45|language=ru|access-date=2024-07-01|archive-url=https://web.archive.org/web/20240629125001/http://ig.ufaras.ru/File/E2014/05_01_14.pdf#page=5|archive-date=2024-06-29|url-status=live}}

The Komstad Regressive Event roughly corresponds to the Dapingian.{{cite journal|author1=N. V. Sennikov|author2=O. T. Obut|author3=E. V. Lykova|author4=A. V. Timokhin|author5=R. A. Khabibulina|author6=T. A. Shcherbanenko|year=2021|url=https://www.gt-crust.ru/jour/article/view/1209/550|title=Event Stratigraphy and Correlation Problems of the Ordovician strata of Gorny Altai and Salair|journal=Geodynamics & Tectonophysics|volume=12|issue=2|page=252|doi=10.5800/GT-2021-12-2-0523|language=ru|doi-access=free|bibcode=2021GeTec..12..246S }}

Funeralaspis, the oldest named odontopleurine trilobite, was discovered in the Dapingian of the Antelope Valley Formation in Inyo County, California.{{cite journal|last1=Adrain|first1=J. M.|last2=Pérez-Peris|first2=F.|year=2023|url=|title=Funeralaspis n. gen.: a new odontopleurine trilobite from the early Middle Ordovician (Dapingian) of Death Valley, eastern California, USA, and the classification of Ordovician odontopleurines|journal=Zootaxa|volume=5336|issue=4|pages=509–529|doi=10.11646/zootaxa.5336.4.3|pmid=38221079}}

Since the Dapingian, there has been a connection between the Afro-European part of Gondwana and Baltica, which is confirmed by the discovery of fossils of cornutan stylophorans Phyllocystis in these regions.{{cite journal|author1=S. V. Rozhnov|author2= G. A. Anekeeva|date=April 2024|url=https://www.researchgate.net/publication/379864348|title=First Specimens of the Cornutan Stylophoran Phyllocystis (Echinodermata) in the Ordovician (Volkhov Regional Stage, Dapingian and Darriwilian) of Baltica and Special Aspects of Stylophoran Axial Symmetry|journal=Paleontological Journal|volume=58|issue=2|pages=181–195|doi=10.1134/S0031030123600300|bibcode= 2024PalJ...58..181R}} Planopora, the oldest сystoporate bryozoan to form erect, bifoliate colonies, is known from the Dapingian of the Baltic paleobasin, Leningrad Oblast, Russia.{{cite journal|author1=Anna V. Koromyslova|author2=Petr V. Fedorov|date=January 2021|url=https://www.researchgate.net/publication/344376823|title=The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia|journal=Journal of Paleontology|volume=95|issue=1|pages=24–39|doi=10.1017/jpa.2020.73|bibcode=2021JPal...95...24K }}

{{Reflist}}

• {{cite web|url=https://timescalefoundation.org/gssp/image.php?periodid=138&top_parentid=77&imageid=375|title=GSSP for base of the Middle Ordovician (base of Dapingian Stage) at the Huanghuachang Section, Yichang, Hubei, South China|website=timescalefoundation.org|language=en|archive-url=https://web.archive.org/web/20240404223918/https://timescalefoundation.org/gssp/image.php?periodid=138&top_parentid=77&imageid=375|archive-date=2024-04-04|url-status=live}}
• {{cite web|title=GSSP Table - Paleozoic Era|url=https://timescalefoundation.org/gssp/index.php?parentid=77|website=timescalefoundation.org|language=en|archive-url=https://web.archive.org/web/20231008002417/https://timescalefoundation.org/gssp/index.php?parentid=77|archive-date=2023-10-08|url-status=live}}
• {{cite web|url=https://ordovician.stratigraphy.org/dapingian|title=Dapingian|publisher=Subcommission on Ordovician Stratigraphy|language=en|archive-url=https://web.archive.org/web/20210618091057/https://ordovician.stratigraphy.org/dapingian|archive-date=2021-06-18|url-status=live}}

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Category:Ordovician geochronology