Zealandia

Topography of Zealandia, outlined in pink. The linear ridges running north-northeast (Colville to the west and Kermadec to the east, separated by the Havre Trough and Lau Basin) and southwest (the Resolution Ridge System) away from New Zealand are not considered part of Zealandia, nor are Australia (left), Vanuatu, or Fiji (top centre).^[1]

Zealandia (pronounced /ziːˈlændiə/), also known as Te Riu-a-Māui (Māori)^[2] or Tasmantis (from Tasman Sea),^[3][4] is an almost entirely submerged mass of continental crust in Oceania that subsided after breaking away from Gondwana 83–79 million years ago.^[5] It has been described variously as a submerged continent, continental fragment, and microcontinent.^[6] The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995,^[7] and satellite imagery shows it to be almost the size of Australia.^[8] A 2021 study suggests Zealandia is 1 billion years old, about twice as old as geologists previously thought.^[9]

By approximately 23 million years ago, the landmass may have been completely submerged.^[10][11] Today, most of the landmass (94%) remains submerged beneath the Pacific Ocean.^[12] New Zealand is the largest part of Zealandia that is above sea level, followed by New Caledonia.

Mapping of Zealandia concluded in 2023.^[13] With a total area of approximately 4,900,000 km² (1,900,000 sq mi),^[6] Zealandia is substantially larger than any features termed microcontinents and continental fragments. If classified as a microcontinent, Zealandia would be the world's largest microcontinent. Its area is six times the area of Madagascar , the next-largest microcontinent in the world,^[6] and more than half the area of the Australian continent. Zealandia is more than twice the size of the largest intraoceanic large igneous province (LIP) in the world, the Ontong Java Plateau (approximately 1,900,000 km² or 730,000 sq mi), and the world's largest island, Greenland (2,166,086 km² or 836,330 sq mi). Zealandia is also substantially larger than the Arabian Peninsula (3,237,500 km² or 1,250,000 sq mi), the world's largest peninsula, and the Indian subcontinent (4,300,000 km² or 1,700,000 sq mi). Due to these and other geological considerations, such as crustal thickness and density,^[14][15] some geologists from New Zealand, New Caledonia, and Australia have concluded that Zealandia fulfills all the requirements to be considered a continent rather than a microcontinent or continental fragment.^[6] Geologist Nick Mortimer (de) commented that if it were not for the ocean level, it would have been recognised as such long ago.^[16]

Zealandia supports substantial inshore fisheries and contains gas fields, of which the largest known is the New Zealand Maui gas field, near Taranaki. Permits for oil exploration in the Great South Basin were issued in 2007.^[17] Offshore mineral resources include ironsands, volcanic massive sulfides and ferromanganese nodule deposits.^[18]

Etymology

GNS Science recognises two names for the landmass. In English, the most common name is Zealandia, a latinate name for New Zealand; the name was coined in the mid-1990s and became established through common use. In the Māori language, the landmass is named Te Riu-a-Māui, meaning 'the hills, valleys, and plains of Māui'.^[2]

Geology

{{#section-h:Geology of Zealandia|Geology}}

Biogeography

New Caledonia is at the northern end of the ancient continent, while New Zealand rises at the plate boundary that bisects it. These land masses constitute two outposts of the Antarctic flora, featuring araucarias and podocarps. At Curio Bay, logs of a fossilized forest closely related to modern Kauri and Norfolk pine can be seen that grew on Zealandia approximately 180 million years ago during the Jurassic period, before it split from Gondwana.^[19] The trees growing in these forests were buried by volcanic mud flows and gradually replaced by silica to produce the fossils now exposed by the sea.

As sea levels drop during glacial periods, more of Zealandia becomes a terrestrial environment rather than a marine environment. Originally, it was thought that Zealandia had no native land mammal fauna, but the discovery in 2006 of a fossil mammal jaw from the Miocene in the Otago region demonstrates otherwise.^[20]

Political divisions

File:Zealandia EEZs.tif

The total land area (including inland water bodies) of Zealandia is 286,660.25 km² (110,680.14 sq mi). Of this, New Zealand comprises the overwhelming majority, at 267,988 km² (103,471 sq mi, or 93.49%) that includes the mainland (North Island and South Island), nearby islands, and most outlying islands, including the Chatham Islands, the New Zealand Subantarctic Islands, the Solander Islands, and the Three Kings Islands (but not the Kermadec Islands or Macquarie Island (Australia ), which are part of the rift).^[21]

New Caledonia and the islands surrounding it comprise some 18,576 km² (7,172 sq mi or 6.48%) and the remainder is made up of various territories of Australia including the Lord Howe Island Group (New South Wales) at 56 km² (22 sq mi or 0.02%), Norfolk Island at 35 km² (14 sq mi or 0.01%), as well as the Cato, Elizabeth, and Middleton reefs (Coral Sea Islands Territory) with 5.25 km² (2.03 sq mi).^[21][22]

Population

(As of 2024) the total human population of Zealandia is approximately 5.4 million people. The largest city is Auckland with about 1.7 million people; roughly one-third of the total population of the continent.

•  New Zealand – 5,112,300^[23]
•  New Caledonia (France ) – 268,767^[24]
•  Norfolk Island (Australia ) – 1,748^[25]
• Template:Country data Lord Howe Island (Australia ) – 382^[26]
• Template:Country data Coral Sea Islands Cato Reef (Australia ) – 0
• Template:Country data Coral Sea Islands Elizabeth Reef (Australia ) – 0
• Template:Country data Coral Sea Islands Middleton Reef (Australia ) – 0

See also

• Australia (continent)
• Exclusive economic zone of New Zealand
• New Zealand Subantarctic Islands

References

External links

• "Zealandia: Earth's Hidden Continent". https://www.geosociety.org/gsatoday/archive/27/3/article/GSATG321A.1.htm. 
• "E Tūhura - Explore Zealandia A portal for geoscience webmaps and information on the Te Riu-a-Māui / Zealandia region". https://data.gns.cri.nz/tez/index.html?content=/mapservice/Content/Zealandia/Home.html. 
• "Zealandia: the New Zealand (drowned) Continent". http://www.teara.govt.nz/EarthSeaAndSky/OceanStudyAndConservation/SeaFloorGeology/1/en. 
• Zealandia (National Geographic Encyclopedia)
• Is Zealandia a continent?
• The missing continent that took 375 years to find, By Zaria Gorvett, 7th February 2021, BBC website.
• Earth Has a Hidden 8th Continent, By Tia Ghose published February 17, 2017, livescience website.

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