Aptian

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 0.6 Ma to 113.2 ± 0.3 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous.^[1]

The Aptian partly overlaps the upper part of the Western European Urgonian Stage.

The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years,^[2]^[3]^[4] being marked by enhanced silicate weathering,^[5] as well as ocean acidification.^[6] The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.^[7]

Stratigraphic definitions

The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its crystallized fruits. The original type locality is in the vicinity of Apt. The Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840.

Subdivision

In the Tethys domain, the Aptian contains eight ammonite biozones:

zone of Hypacanthoplites jacobi
zone of Nolaniceras nolani
zone of Parahoplites melchioris
zone of Epicheloniceras subnodosocostatum
zone of Duffrenoyia furcata
zone of Deshayesites deshayesi
zone of Deshayesites weissi
zone of Deshayesites oglanlensis

Sometimes the Aptian is subdivided in three substages or subages: Bedoulian (early or lower), Gargasian (middle) and Clansayesian (late or upper). In modern formal chronostratigraphy the Aptian is divided into Lower and Upper sub-stages. The Lower Aptian is almost equivalent to the Bedoulian (without the Dufrenoyia furcata Zone), and it includes the 3 "Deshayesites" ammonite zones. The Upper Aptian spans the Gargasian and Clansayesian intervals, it includes the furcata to jacobi Tethys ammonite zones (Moullade et al. 2011 ^[8]).

Lithostratigraphic units

Examples of rock units formed during the Aptian are: Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group and Yixian Formation.

Climate

A cold episode occurred at the start of the Aptian, as evidenced by the migration of the dinoflagellates Cepadinium variabilis and Pseudoceratium nohrhansenii into lower latitudes.^[9] A decline in global pCO₂ occurred from about 1,000 ppm to 800 ppm from the start of the Aptian to the C10 positive carbon isotope excursion.^[10] During the late Aptian, pCO₂ was between 515 ± 79 and 1029.8 ± 158 ppm as evidenced by the stomatal density of Pseudofrenelopsis capillata.^[11]

References

Notes

↑ Gradstein et al. (2004)
↑ Blok, C. N.; Ineson, J.; Anderskouv, K.; Fantasia, A.; Sheldon, E.; Thibault, N.; Jelby, M. E.; Adatte, T. et al. (1 September 2022). "Latitude-dependant climate changes across the Aptian Oceanic Anoxic Event 1a". Palaeogeography, Palaeoclimatology, Palaeoecology 601. doi:10.1016/j.palaeo.2022.111085. Bibcode: 2022PPP...60111085B.
↑ Li, Yong-Xiang; Bralower, Timothy J.; Montañez, Isabel P.; Osleger, David A.; Arthur, Michael A.; Bice, David M.; Herbert, Timothy D.; Erba, Elisabetta et al. (15 July 2008). "Toward an orbital chronology for the early Aptian Oceanic Anoxic Event (OAE1a, ~ 120 Ma)". Earth and Planetary Science Letters 271 (1–4): 88–100. doi:10.1016/j.epsl.2008.03.055. Bibcode: 2008E&PSL.271...88L.
↑ Leckie, R.; Bralower, Timothy J.; Cashman, R. (2002). "Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the mid-Cretaceous". Paleoceanography and Paleoclimatology 17 (3): 1–29. doi:10.1029/2001pa000623. Bibcode: 2002PalOc..17.1041L. https://www.geo.umass.edu/faculty/leckie/Leckie%20et%20al.%202002.pdf.
↑ Lechler, Maria; Von Strandmann, Philip A. E. Pogge; Jenkyns, Hugh C.; Prosser, Giacomo; Parente, Mariano (15 December 2015). "Lithium-isotope evidence for enhanced silicate weathering during OAE 1a (Early Aptian Selli event)". Earth and Planetary Science Letters 432: 210–222. doi:10.1016/j.epsl.2015.09.052. Bibcode: 2015E&PSL.432..210L. https://www.sciencedirect.com/science/article/abs/pii/S0012821X15006299. Retrieved 30 September 2022.
↑ Erba, Elisabetta; Bottini, Cinzia; Weissert, Helmut J.; Keller, Christina E. (23 July 2010). "Calcareous Nannoplankton Response to Surface-Water Acidification Around Oceanic Anoxic Event 1a". Science 329 (5990): 428–432. doi:10.1126/science.1188886. PMID 20651148. Bibcode: 2010Sci...329..428E. https://www.science.org/doi/10.1126/science.1188886. Retrieved 24 January 2023.
↑ Archangelsky, Sergio. "The Ticó Flora (Patagonia) and the Aptian Extinction Event." Acta Paleobotanica 41(2), 2001, pp. 115-22.
↑ Moullade, Michel; Granier, Bruno; Tronchetti, Guy (2011). "The Aptian Stage: Back to fundamentals". Episodes 34 (3): 148–156. doi:10.18814/epiiugs/2011/v34i3/002.
↑ Boukhamsin, Hani; Peyrot, Daniel; Lang, Simon; Vecoli, Marco (January 2022). "Low-latitude ?upper Barremian–lower Aptian palynoflora and paleovegetation of the Biyadh Formation (Arabian Plate, eastern margin of northern Gondwana): evidence for a possible cold snap" (in en). Cretaceous Research 129. doi:10.1016/j.cretres.2021.104995. Bibcode: 2022CrRes.12904995B. https://www.sciencedirect.com/science/article/pii/S0195667121002433. Retrieved 1 November 2024.
↑ Ludvigson, G.A.; Joeckel, R.M.; Murphy, L.R.; Stockli, D.F.; González, L.A.; Suarez, Celina A.; Kirkland, James I.; Al-Suwaidi, A. (September–December 2015). "The emerging terrestrial record of Aptian-Albian global change" (in en). Cretaceous Research 56: 1–24. doi:10.1016/j.cretres.2014.11.008. Bibcode: 2015CrRes..56....1L. https://www.sciencedirect.com/science/article/pii/S0195667114002195. Retrieved 1 November 2024.
↑ Degani-Schmidt, Isabela; Guerra-Sommer, Margot; Carvalho, Ismar de Souza (June 2023). "Stomatal numbers of Pseudofrenelopsis capillata (Cheirolepidiaceae, Coniferales) in the peri-equatorial late Aptian Crato Formation (Santana group, Araripe Basin, Brazil) and their paleoclimatic and paleoenvironmental significance" (in en). Journal of South American Earth Sciences 126. doi:10.1016/j.jsames.2023.104331. Bibcode: 2023JSAES.12604331D. https://www.sciencedirect.com/science/article/pii/S0895981123001426. Retrieved 1 November 2024.

Literature

Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
Orbigny, A.C.V.M. d'; 1842: Paléontologie française: Terrains crétacés, vol. ii. (in French)

External links

GeoWhen Database - Aptian
Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic charts of the Lower Cretaceous: [1] and [2], at the website of Norges Network of offshore records of geology and stratigraphy

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Original source: https://en.wikipedia.org/wiki/Aptian. Read more

[1] Gradstein et al. (2004)

[2] Blok, C. N.; Ineson, J.; Anderskouv, K.; Fantasia, A.; Sheldon, E.; Thibault, N.; Jelby, M. E.; Adatte, T. et al. (1 September 2022). "Latitude-dependant climate changes across the Aptian Oceanic Anoxic Event 1a". Palaeogeography, Palaeoclimatology, Palaeoecology 601. doi:10.1016/j.palaeo.2022.111085. Bibcode: 2022PPP...60111085B.

[Li2008-3] Li, Yong-Xiang; Bralower, Timothy J.; Montañez, Isabel P.; Osleger, David A.; Arthur, Michael A.; Bice, David M.; Herbert, Timothy D.; Erba, Elisabetta et al. (15 July 2008). "Toward an orbital chronology for the early Aptian Oceanic Anoxic Event (OAE1a, ~ 120 Ma)". Earth and Planetary Science Letters 271 (1–4): 88–100. doi:10.1016/j.epsl.2008.03.055. Bibcode: 2008E&PSL.271...88L.

[oaedef-4] Leckie, R.; Bralower, Timothy J.; Cashman, R. (2002). "Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the mid-Cretaceous". Paleoceanography and Paleoclimatology 17 (3): 1–29. doi:10.1029/2001pa000623. Bibcode: 2002PalOc..17.1041L. https://www.geo.umass.edu/faculty/leckie/Leckie%20et%20al.%202002.pdf.

[MariaLechler2015-5] Lechler, Maria; Von Strandmann, Philip A. E. Pogge; Jenkyns, Hugh C.; Prosser, Giacomo; Parente, Mariano (15 December 2015). "Lithium-isotope evidence for enhanced silicate weathering during OAE 1a (Early Aptian Selli event)". Earth and Planetary Science Letters 432: 210–222. doi:10.1016/j.epsl.2015.09.052. Bibcode: 2015E&PSL.432..210L. https://www.sciencedirect.com/science/article/abs/pii/S0012821X15006299. Retrieved 30 September 2022.

[6] Erba, Elisabetta; Bottini, Cinzia; Weissert, Helmut J.; Keller, Christina E. (23 July 2010). "Calcareous Nannoplankton Response to Surface-Water Acidification Around Oceanic Anoxic Event 1a". Science 329 (5990): 428–432. doi:10.1126/science.1188886. PMID 20651148. Bibcode: 2010Sci...329..428E. https://www.science.org/doi/10.1126/science.1188886. Retrieved 24 January 2023.

[7] Archangelsky, Sergio. "The Ticó Flora (Patagonia) and the Aptian Extinction Event." Acta Paleobotanica 41(2), 2001, pp. 115-22.

[8] Moullade, Michel; Granier, Bruno; Tronchetti, Guy (2011). "The Aptian Stage: Back to fundamentals". Episodes 34 (3): 148–156. doi:10.18814/epiiugs/2011/v34i3/002.

[9] Boukhamsin, Hani; Peyrot, Daniel; Lang, Simon; Vecoli, Marco (January 2022). "Low-latitude ?upper Barremian–lower Aptian palynoflora and paleovegetation of the Biyadh Formation (Arabian Plate, eastern margin of northern Gondwana): evidence for a possible cold snap" (in en). Cretaceous Research 129. doi:10.1016/j.cretres.2021.104995. Bibcode: 2022CrRes.12904995B. https://www.sciencedirect.com/science/article/pii/S0195667121002433. Retrieved 1 November 2024.

[10] Ludvigson, G.A.; Joeckel, R.M.; Murphy, L.R.; Stockli, D.F.; González, L.A.; Suarez, Celina A.; Kirkland, James I.; Al-Suwaidi, A. (September–December 2015). "The emerging terrestrial record of Aptian-Albian global change" (in en). Cretaceous Research 56: 1–24. doi:10.1016/j.cretres.2014.11.008. Bibcode: 2015CrRes..56....1L. https://www.sciencedirect.com/science/article/pii/S0195667114002195. Retrieved 1 November 2024.

[11] Degani-Schmidt, Isabela; Guerra-Sommer, Margot; Carvalho, Ismar de Souza (June 2023). "Stomatal numbers of Pseudofrenelopsis capillata (Cheirolepidiaceae, Coniferales) in the peri-equatorial late Aptian Crato Formation (Santana group, Araripe Basin, Brazil) and their paleoclimatic and paleoenvironmental significance" (in en). Journal of South American Earth Sciences 126. doi:10.1016/j.jsames.2023.104331. Bibcode: 2023JSAES.12604331D. https://www.sciencedirect.com/science/article/pii/S0895981123001426. Retrieved 1 November 2024.

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