Seymour Island

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Seymour Island
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Seymour Island
Antarctic Peninsula
Geography
Location Antarctica
Coordinates 64°14′S56°37′W / 64.233°S 56.617°W / -64.233; -56.617
Archipelago James Ross Island group
Administration
None
Demographics
Population0
[1]
Geologic map of Seymour Island, Antarctica Geologic map of Seymour Island, Antarctica.png
Geologic map of Seymour Island, Antarctica

Seymour Island or Marambio Island, is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is the closest part of Antarctica to South America. [2] It lies within the section of the island chain that resides off the west side of the peninsula's northernmost tip. Within that section, it is separated from Snow Hill Island by Picnic Passage, and sits just east of the larger key, James Ross Island, and its smaller, neighboring island, Vega Island.

Contents

Seymour Island is sometimes called Marambio Island or Seymour-Marambio Island, taking its resident Argentine base as its namesake (see section, Base Antárctica Marambio, below).

Historic site

A wooden plaque and rock cairn stand at Penguins Bay, on the southern coast of Seymour Island. The plaque was placed on 10 November 1903 by the crew of the Argentinian Corvette Uruguay on a mission to rescue the members of the Swedish expedition led by Otto Nordenskiöld. The inscription on the plaque, placed where the two parties met, reads:

“10.XI.1903 Uruguay (Argentine Navy) in its journey to give assistance to the Swedish Antarctic expedition”.

The cairn was erected in January 1990 by Argentina at the site of the plaque in commemoration of the same event. The site has been designated a Historic Site or Monument (HSM 60), following a proposal by Argentina to the Antarctic Treaty Consultative Meeting. [3]

Base Antárctica Marambio

Located in the island is the Marambio Base which is the main Argentine base in Antarctica operating an airfield (ICAO SAWB) for wheeled landing the whole year. [4] In winter the base has an average of 55 crew members, but in summer the population of the base can grow to 180. [5]

Climate

The average temperatures on Seymour Island, as measured at Base Antárctica Marambio, are 1 °C (33.8 °F) during the summer and −21 °C (−5.8 °F) during the winter. In the wintertime, however, strong winds can lower the wind chill temperature feeling to as low as −60 °C (−76 °F) on exposed skin. On 9 February 2020, a temperature of 20.75 °C (69.3 °F) was recorded on the island. [6] However, on 1 July 2021, the World Meteorological Organization invalidated the reading because based on the analysis of the data, the air temperature was recorded in non-standard conditions, leading to bias and errors in the temperature sensor and readings. [7] [8]

Paleontological significance

The rocks making up Seymour Island date mainly from the Late Cretaceous to the Eocene. Successively younger rock formations found on the island are the López de Bertodano Formation (Cretaceous to early Paleocene), Sobral Formation and Cross Valley Formation (Paleocene) and La Meseta Formation (Eocene). Seymour Island has been referred to as the Rosetta Stone of Antarctic palaeontology, due to the unparalleled insight it provides into the geological and palaeontological history of the continent.

In December 1892 [9] when Norwegian Captain, Carl Anton Larsen landed his ship, the Jason, on Seymour Island, he returned with more than maps of the territory, he found fossils of long-extinct species. Larsen's trip aboard the Jason was significantly more successful than his Swedish Antarctic Expedition journey between 1901 and 1904 [10] . During that trip, his ship, the Antarctic, was crushed and sunk by icebergs, and he and his crew were forced to weather fourteen months on the neighboring Snow Hill Island, surviving on penguins and seals. Ever since his voyage on the Jason, the island has been the subject of paleontological study.

The Cretaceous-Paleogene boundary (K-Pg) crops out on Seymour Island in the upper levels of the López de Bertodano Formation. [11] A small (but significant) iridium anomaly occurs at the boundary on Seymour Island, as at lower latitudes, thought to be fallout from the Chicxulub impactor in the Gulf of Mexico. [12] Directly above the boundary a layer of disarticulated fish fossils occurs, victims of a disturbed ecosystem immediately following the impact event. [11] Multiple reports have described evidence for climatic changes in Antarctica prior to the mass extinction, [13] but the extent to which these affected marine biodiversity is debated. Based on extensive marine fossil collections from Seymour Island, recent work has confirmed that a single and severe mass extinction event occurred at this time in Antarctica just as at lower latitudes. [14]

Seymour Island has also been the site of much study of the Eocene Epoch of climatic cooling, a process that culminated in the initiation of Antarctic glaciation. Studies of the fine fraction carbonate from sites in the Southern Ocean suggest that, rather than a monotonic decrease in temperature over the Eocene Epoch, the middle of the epoch was punctuated by a brief duration of warming (Bohaty and Zachos, 2003). [15]

Seymour Island has been a site of study of many fossils from this particular part of the Eocene Epoch, during which there was a more flourishing ecosystem with diverse biota as a result of the warmer climate. A diverse array of fossilized species has been studied on the island, including extinct penguin species (such as Palaeeudyptes klekowskii and Archaeospheniscus wimani ), various species in the bivalvia class and various types of flora and fauna, including a frog. [15] [16]

A fossil marsupial of the extinct family Polydolopidae was found on Seymour Island in 1982. [17] This was the first evidence of land mammals having lived in Antarctica. Further fossils have subsequently been found, including members of the marsupial orders Didelphimorphia (opossum) and Microbiotheria, [18] as well as ungulates and a member of the enigmatic extinct order Gondwanatheria, possibly Sudamerica ameghinoi . [19] [20] [21]

IUGS geological heritage site

In respect of the site being the 'most representative high latitude K-Pg boundary location and one of the most significant and best exposed globally' the 'Cretaceous-Paleogene Transition at Seymour (Marambio) Island' was included by the International Union of Geological Sciences (IUGS) in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an 'IUGS Geological Heritage Site' as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.' [22]

Features

See also

Related Research Articles

<span class="mw-page-title-main">Cenozoic</span> Third era of the Phanerozoic Eon

The Cenozoic is Earth's current geological era, representing the last 66 million years of Earth's history. It is characterised by the dominance of mammals, birds, and angiosperms. It is the latest of three geological eras, preceded by the Mesozoic and Paleozoic. The Cenozoic started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor.

<span class="mw-page-title-main">Eocene</span> Second epoch of the Paleogene Period

The Eocene Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ἠώς and καινός and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.

<span class="mw-page-title-main">Paleogene</span> First period of the Cenozoic Era (66–23 million years ago)

The Paleogene Period is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 million years ago (Mya) to the beginning of the Neogene Period 23.03 Mya. It is the first part of the Cenozoic Era of the present Phanerozoic Eon. The earlier term Tertiary Period was used to define the span of time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use. Paleogene is often abbreviated "Pg", although the United States Geological Survey uses the abbreviation "Pe" for the Paleogene on the Survey's geologic maps.

<span class="mw-page-title-main">Antarctic Peninsula</span> Peninsula located in northern Antarctica

The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctica.

The Late Cretaceous is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after creta, the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period.

<span class="mw-page-title-main">South Polar region of the Cretaceous</span> Animals that lived below the Antarctic circle in the Cretaceous

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Polarornis is a genus of prehistoric bird, possibly an anserimorph. It contains a single species Polarornis gregorii, known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are dated to the Late Cretaceous.

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The Paleocene, or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek παλαιός palaiós meaning "old" and the Eocene Epoch, translating to "the old part of the Eocene".

The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous to the Danian stage of the lower Paleocene, from about 70 to 65.5 million years ago, straddling the Cretaceous-Paleogene boundary.

<span class="mw-page-title-main">Santa Marta Formation</span>

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<span class="mw-page-title-main">Sobral Formation</span> Paleontological Formation in Antarctica

The Sobral Formation is a palaeontological formation located in Antarctica. It dates to the Danian stage of the Lower Paleocene period.

Ampheristus is an extinct genus of prehistoric marine ray-finned fish. It was a basal or stem member of the family Ophidiidae, which contains modern cusk-eels. Fossils are known from worldwide from the Late Cretaceous to the late Paleogene, making it a rather successful survivor of the Cretaceous-Paleogene extinction event.

<span class="mw-page-title-main">Cariamiformes</span> Order of birds

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<span class="mw-page-title-main">La Meseta Formation</span>

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<span class="mw-page-title-main">Cretaceous–Paleogene extinction event</span> Mass extinction event about 66 million years ago

The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary(K–T)extinction, was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than 25 kilograms also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the Cenozoic era, which continues to this day.

<i>Kaikaifilu</i> Extinct genus of marine squamate reptiles

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References

  1. ↑ Administered under the Antarctic Treaty System
  2. ↑ ESA Science & Technology: Graham Land
  3. ↑ "List of Historic Sites and Monuments approved by the ATCM (2012)" (PDF). Antarctic Treaty Secretariat. 2012. Retrieved 4 January 2014.
  4. ↑ Antarctic facilities Archived 2008-04-24 at the Wayback Machine – comnap.aq
  5. ↑ official page Archived 2013-12-03 at the Wayback Machine
  6. ↑ Watts, Jonathan (13 February 2020). "Antarctic temperature rises above 20C for first time on record". The Guardian. ISSN   0261-3077 . Retrieved 13 February 2020.
  7. ↑ "WMO verifies one temperature record for Antarctic continent and rejects another". World Meteorological Organization. 1 July 2021. Retrieved 3 July 2021.
  8. ↑ "WMO verifies highest temperatures for Antarctic Region". World Meteorological Organization. 1 March 2017. Archived from the original on 18 December 2023. Retrieved 13 February 2020.
  9. ↑ Tønnessen, Joh. N. (1982). The History of Modern Whaling. University of California Press. p. 150. ISBN   978-0-520-03973-5.
  10. ↑ Babcock, L. E.; Feldmann, R. M.; Grunow, A. M. (2024). "Cretaceous–Palaeogene lobsters, Hoploparia stokesi (Weller, 1903), from Antarctica: historical review, and transfer of specimens from the United States Polar Rock Repository". Polar Research. 43 (9866): 1–5. doi:10.33265/polar.v43.9866.
  11. 1 2 Zinsmeister, W.J. (1998). "Discovery of fish mortality horizon at the K-T Boundary on Seymour Island: Re-evaluation of events at the end of the Cretaceous". Journal of Paleontology. 72 (3): 556–571. doi:10.1017/S0022336000024331. S2CID   132206016.
  12. ↑ Elliot, D.H.; Askin, R.A.; Kyte, F.T.; Zinsmeister, W.J. (1994). "Iridium and dinocysts at the Cretaceous-Tertiary boundary on Seymour Island, Antarctica: Implications for the K-T event". Geology. 22 (8): 675. Bibcode:1994Geo....22..675E. doi:10.1130/0091-7613(1994)022<0675:IADATC>2.3.CO;2.
  13. ↑ Petersen, S.V.; Dutton, A.; Lohmann, K.C. (2016). "End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change". Nature Communications. 7: 12079. Bibcode:2016NatCo...712079P. doi:10.1038/ncomms12079. PMC   4935969 . PMID   27377632.
  14. ↑ Witts, JD; Whittle, RJ; Wignall, PB; Crame, JA; Francis, JE; Newton, RJ; Bowman, VC (2016). "Macrofossil evidence for a rapid and severe Cretaceous-Paleogene mass extinction in Antarctica". Nature Communications. 7: 11738. Bibcode:2016NatCo...711738W. doi:10.1038/ncomms11738. PMC   4894978 . PMID   27226414.
  15. 1 2 "Middle Eocene Warming On Seymour Island, Antarctica: Continental Shelf Paleotemperatures Recorded In Molluscan Carbonates". Archived from the original on 21 August 2008. Retrieved 9 February 2007.
  16. ↑ Mörs, Thomas; Reguero, Marcelo; Vasilyan, Davit (2020). "First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia". Scientific Reports. 10 (1): 5051. Bibcode:2020NatSR..10.5051M. doi:10.1038/s41598-020-61973-5. PMC   7181706 . PMID   32327670.
  17. ↑ Woodburne, Michael O.; Zinsmeister, William J. (October 1982). "Fossil Land Mammal from Antarctica". Science. 218 (4569): 284–286. Bibcode:1982Sci...218..284W. doi:10.1126/science.218.4569.284. PMID   17838631. S2CID   32304737.
  18. ↑ Goin, Francisco J.; et al. (December 1999). "New Discoveries of "Opposum-Like" Marsupials from Antarctica (Seymour Island, Medial Eocene)". Journal of Mammalian Evolution. 6 (4): 335–365. doi:10.1023/A:1027357927460. S2CID   2319361.
  19. ↑ Reguero, Marcelo A.; Marenssi, Sergio A.; Santillana, Sergio N. (May 2002). "Antarctic Peninsula and South America (Patagonia) Paleogene terrestrial faunas and environments: biogeographic relationships". Palaeogeography, Palaeoclimatology, Palaeoecology. 179 (3–4): 189–210. Bibcode:2002PPP...179..189R. doi:10.1016/S0031-0182(01)00417-5.
  20. ↑ Mills, William James. Exploring Polar Frontiers: A Historical Encyclopedia, ABC-CLIO, 2003. ISBN   1-57607-422-6, ISBN   978-1-57607-422-0
  21. ↑ Goin, F.J.; Reguero, M.A.; Pascual, R.; von Koenigswald, W.; Woodburne, M.O.; Case, J.A.; Marenssi, S.A.; Vieytes, C.; Vizcaíno, S.F. (2006). "First gondwanatherian mammal from Antarctica". Geological Society, London, Special Publications. 258 (1): 135–144. Bibcode:2006GSLSP.258..135G. doi:10.1144/GSL.SP.2006.258.01.10. S2CID   129493664.
  22. ↑ "The First 100 IUGS Geological Heritage Sites" (PDF). IUGS International Commission on Geoheritage. IUGS. Retrieved 10 November 2022.
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