Continental fragment in the context of "Jan Mayen"

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

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

A submerged continent or a sunken continent is a region of continental crust, extensive in size but mainly undersea. The terminology is used by some paleogeologists and geographers in reference to some landmasses (none of which are as large as any of the seven generally-recognized continents).

The definition of this term is unclear. If continental fragments and microcontinents smaller than 2,500,000 km (970,000 sq mi), which is approximately one third of the area of mainland Australia, are excluded, then Zealandia (approximately 4,900,000 km or 1,900,000 sq mi) would be the only geological feature which is classifiable as a submerged continent.

The Mascarene Islands (English: /mæskəˈriːn/; French: Mascareignes [maskaʁɛɲ] ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their name derives from the Portuguese navigator Pedro Mascarenhas, who first visited them in April 1512. The islands share a common geological origin beneath the Mascarene Plateau known as the Mauritia microcontinent which was a Precambrian microcontinent situated between India and Madagascar until their separation about 70 million years ago. They form a distinct ecoregion with unique biodiversity and endemism of flora and fauna.

The Scotia Arc is the island arc system forming the north, east and south border of the Scotia Sea. The northern border, the North Scotia Ridge, comprises (from west to east): Isla de los Estados at the tip of Tierra del Fuego, the Burdwood, Davis, and Aurora Banks; the Shag, South Georgia Island and Clerke Rocks. The eastern border comprises the volcanic South Sandwich Islands flanked by the South Sandwich Trench. The southern border, the South Scotia Ridge, comprises (east to west): Herdman, Discovery, Bruce, Pirie, and Jane Banks; the South Orkney Islands and Elephant Island. Finally, the Bransfield Strait separates the arc from the South Shetland Islands and James Ross Island flanking the tip of the Antarctic Peninsula.

The Scotia Arc surrounds the small Scotia and South Sandwich Plates.The arc is formed by continental fragments that once formed a land bridge between South America and Antarctica, which was once part of the subduction margin that still forms the Andes. An ancestral arc, which formed a separate subduction system, broke through this land bridge and started to form the Scotia Sea by eastward back-arc extension driven by subduction of the South American Plate (also located east of the Scotia Arc).Today, the Scotia Arc forms a discontinuous link between South America and Antarctica. It is considered a continuation of the Andes, and the antarctic part of that mountain range is called the Antarctandes. The Scotia Arc is also an important barrier between the Pacific and Atlantic Oceans, and therefore for the Antarctic Circumpolar Current.