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Published on Oct 13, 2015
This animation illustrates the plate tectonic evolution of the Indian Ocean from 200 million years ago to the present-day. The colored lines are "seafloor spreading isochrons" that mark the location of the ancient mid-ocean ridges. The red dots and red +'s are the location of mantle plumes or "hotspots". The black "blobs" are volcanic islands and plateaus that, like Hawaii, were produced by the hot spots.
Hot spots are formed were a plume of magma erupts from deep within the Earth. Like a volcanic "fire-hose" a tremendous amount of lava is erupted above this "hot spot". When hotspots first erupt at the Earth;s surface they often cover the land with a thick (2-3 km) pile of volcanics. These volcanic features are known as "flood basalts" or LIPS (Large Igneous Provinces). As the moving plate travels above a hotspot the erupting lava forms islands (like Hawaii) or volcanic ridges ( Ninety East ) and plateaus (Kerguelun Plateau).
Three very long-lived hotspots are worth following. The Reunion Hotspot, located at the center of the screen, first appeared 65 million years ago. Lava flows 2-3 kilometers thick covered much of India (Deccan Traps). The eruption of the Deccan flood basalts is thought to have played a role in the extinction of the dinosaurs. As India moved northward the Reunion Hotspot created the the Chagos-Laccadive Island chain, Nazarene Bank, Mauritius, and Reunion island.
The Kerguelun hotspot is another important, long-lived hot spot. The Kerguelun first erupted about 100 million years ago producing the Rajmahal Traps in NE India. Between 100 Ma and 85 Ma, the Kerguelen Hotspot built up the Kerguelun Plateau. During the late Cretaceous and early Cenozoic, India moved rapidly northward. The 90 East Ridge is a series of volcanic islands that were formed above the Kerguelun Hotspot.
The Tristan Hotspot, in the South Atlantic, is a third long-lived hotspot. Active from 180 million years ago to the present-day, the Tristan hotspot produced the Walvis Ridge, and may have been responsible for the eruption of the Karoo Flood basalts that once covered much of South Africa.
Can you see any other volcanic features that may have been generated by hotspots?