The Réunion hotspot is a

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

hotspot which currently lies under the island of

Réunion Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...

in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

. The Chagos-Laccadive Ridge and the southern part of the

Mascarene Plateau The Mascarene Plateau is a submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately , from Seychelles in the north to Réunion in the south. The plateau covers an area of over of shallow water, wi ...

are volcanic traces of the Réunion hotspot. The hotspot is believed to have been active for over 65 million years. A huge eruption of this hotspot 65 million years ago is thought to have laid down the Deccan Traps, a vast bed of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

lava that covers part of central

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, and opened a rift which separated India from the Seychelles Plateau. The Deccan Traps eruption coincided roughly with the nearly antipodal

Chicxulub impactor The Chicxulub crater () is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore near the community of Chicxulub, after which it is named. It was formed slightly over 66 million years ago when a large as ...

and the Cretaceous–Paleogene extinction of the

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s, and there is considerable speculation that the three events were related. As the Indian plate drifted north, the hotspot continued to punch through the plate, creating a string of volcanic islands and undersea plateaux. The

Laccadive Islands The Laccadive or Cannanore Islands are one of the three island subgroups in the Union Territory of Lakshadweep, India. It is the central subgroup of the Lakshadweep, separated from the Amindivi Islands subgroup roughly by the 11th parallel ...

, the

Maldives Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...

, and the

Chagos Archipelago The Chagos Archipelago () or Chagos Islands (formerly the Bassas de Chagas, and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives arch ...

are

atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gr ...

s resting on former volcanoes created 60–45 million years ago that subsequently submerged below sea level. About 45 million years ago the

Central Indian Ridge The Central Indian Ridge (CIR) is a north–south-trending mid-ocean ridge in the western Indian Ocean. Geological setting The morphology of the CIR is characteristic of slow to intermediate ridges. The axial valley is 500–1000 m deep; ...

crossed over the hotspot, and the hotspot passed under the

African Plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate ...

. The hotspot appears to have been relatively quiet 45–10 million years ago, when activity resumed, creating the

Mascarene Islands The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...

, which include

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label=Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It incl ...

, and Rodrigues. Mauritius and Rodrigues Ridge were created 8–10 million years ago, and Rodrigues and Réunion Islands in the last two million years.

Piton de la Fournaise Piton de la Fournaise (; en, "Peak of the Furnace") is a shield volcano on the eastern side of Réunion island (a French overseas department and region) in the Indian Ocean. It is currently one of the most active volcanoes in the world, alo ...

, a

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

on the southeastern corner of Réunion, is one of the most active volcanoes in the world, erupting last in December 2020.

References

External links

Origin and compensation of Chagos-Laccadive ridge, Indian ocean, from admittance analysis of gravity and bathymetry data
* - an article accompanied with an interactive model of the hotspot {{DEFAULTSORT:Reunion Hotspot Geography of Réunion Geology of France Hotspots of the Indian Ocean