Taghanic event
386 million years ago
in Middle Devonian period
387.7 ± 0.8 – 382.7 ± 1.6 Ma
↓

The Taghanic event (Taghanic unconformity, Taghanic crisis and Taghanic onlap) was an extinction event about 386 million years ago during the Givetian faunal stage of the Middle Devonian geologic period in the Paleozoic era.[1] The cause of the extinction event is from an anoxic event and hypoxia. The event had a time span when the dissolved oxygen (O2) level in the Earth's oceans were depleted. The Taghanic event caused a very high death rate of corals. The loss of the corals reefs, caused a high loss of animals that lived in and around the reefs. The extinction rate had been placed between 28.5 and 36%, making the event the 8th highest extinction event.[2][3][4] The reduced oxygen levels were caused by a period of global-warming. The global-warming was caused by the Milankovitch cycles. In the Taghanic event sea levels were higher.[5] After the Taghanic Event, sea life recovered in the Frasnian faunal stage starting 382.7 million years ago. The two other events near this time span were the Kellwasser event (372 ma), and the Hangenberg event (359 ma).[6][5][7]

Extinctions

The Taghanic event at the Givetian/Frasnian boundary caused extinctions. About 50% of coral genera disappear. Brachiopods Mollusca lost about six families of species. About 47% Stromatoporoid sea sponges genera disappeared. Many Bryozoa are also lost. The population of Ammonoids, Tabulata, Trilobites, and Rugosa are reduced.[8] The Thamnopora boloniensis, a Tabulate coral, became extinct.[9]

Sediments

Old Red Sandstone continent sediments are studied to evaluate the Taghanic extinction event. Taghanic event is found by studying the sudden sedimentary layer changes, faunal changes, and palaeobiogeographic events.[6] The Taghanic event is found in the Tully Formation and Marcellus Formation found in New York and Pennsylvania, including the Windom shale there. Mahantango Formation in Pennsylvania, West Virginia, and Maryland record the Taghanic event. Taghanic event has also been found in Tafilalt, Morocco in the eastern Anti-Atlas mountain range. Orcadian Basin in Scotland has exposed rocks of the Taghanic event.[10]

Taghanic onlap

The period of global-warming that caused the Taghanic event, melted ice caps that caused sea level to rise. This caused the Taghanic onlap, the submergence of land by the advancing sea. The advancing sea laid down a strata deposits on the seafloor. The flooding of the what is now the southwestern United States created a shallow water marine environment.[3][11][12]

Gallery

CambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
Marine extinction intensity during the Phanerozoic
%
Millions of years ago
CambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
The Taghanic event was just before the Late Devonian (Late D) event. The chart gives a comparison of the extinction event to other mass extinction events in Earth's history. Plotted is the extinction intensity, calculated from marine genera.

See also

References

  1. ^ Marshall, John E. A.; Brown, John F.; Astin, Timothy R. (April 15, 2011). "Recognising the Taghanic Crisis in the Devonian terrestrial environment and its implications for understanding land–sea interactions". Palaeogeography, Palaeoclimatology, Palaeoecology. 304 (1): 165–183. doi:10.1016/j.palaeo.2010.10.016 – via ScienceDirect.
  2. ^ Sepkoski, J. John (December 18, 1996). Walliser, Otto H. (ed.). Global Events and Event Stratigraphy in the Phanerozoic: Results of the International Interdisciplinary Cooperation in the IGCP-Project 216 "Global Biological Events in Earth History". Springer. pp. 35–51. doi:10.1007/978-3-642-79634-0_4 – via Springer Link.
  3. ^ a b Johnson, J. G. (1970). "Taghanic Onlap and the End of North American Devonian Provinciality". Geological Society of America Bulletin. 81 (7): 2077. Bibcode:1970GSAB...81.2077J. doi:10.1130/0016-7606(1970)81[2077:TOATEO]2.0.CO;2.
  4. ^ Feist, R.; Klapper, G. (2021). "Phacopid trilobites in post-Taghanic Givetian through Frasnian cephalopod limestones, Montagne Noire (France) and related areas (Thuringia, Morocco)". Bulletin of Geosciences. 97 (1): 1–32. doi:10.3140/bull.geosci.1834. S2CID 246358282.
  5. ^ a b "Abstract: THE TAGHANIC EVENT: A LATE MID DEVONIAN ARIDITY CRISIS (2003 Seattle Annual Meeting (November 2–5, 2003))". gsa.confex.com.
  6. ^ a b "Late Devonian - an overview | ScienceDirect Topics". www.sciencedirect.com.
  7. ^ McGhee Jr GR, Clapham ME, Sheehan PM, Bottjer DJ, Droser ML (January 2013). "A new ecological-severity ranking of major Phanerozoic biodiversity crises". Palaeogeography, Palaeoclimatology, Palaeoecology. 370: 260–270. Bibcode:2013PPP...370..260M. doi:10.1016/j.palaeo.2012.12.019. ISSN 0031-0182.
  8. ^ Helling, Stephan; Becker, Ralph Thomas (September 1, 2022). "Two new species of Gondwanaspis (Trilobita, Odontopleurida) from the Givetian-Frasnian transition of the northern Rhenish Massif (Germany)". Palaeobiodiversity and Palaeoenvironments. 102 (3): 697–709. doi:10.1007/s12549-022-00525-3 – via Springer Link.
  9. ^ Bridge, Tom C. L.; Baird, Andrew H.; Pandolfi, John M.; McWilliam, Michael J.; Zapalski, Mikołaj K. (January 26, 2022). "Functional consequences of Palaeozoic reef collapse". Scientific Reports. 12: 1386. doi:10.1038/s41598-022-05154-6. PMC 8792005. PMID 35082318 – via PubMed Central.
  10. ^ Aboussalam, Z. Sarah; Becker, R. Thomas (April 15, 2011). "The global Taghanic Biocrisis (Givetian) in the eastern Anti-Atlas, Morocco". Palaeogeography, Palaeoclimatology, Palaeoecology. 304 (1): 136–164. doi:10.1016/j.palaeo.2010.10.015 – via ScienceDirect.
  11. ^ Graham, John Paul. "Devonian carbonate rocks , Plate8.jpg". ir.library.oregonstate.edu.
  12. ^ "Abstract: Global Taghanic and Givetian Seawater Records: An Amelioration of Faunal Realms, Climatic Conditions and High Levels of Atmospheric Carbon Dioxide ( 2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM)". gsa.confex.com.
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