Hotspots driving tectonic plate movement | Nature | The Earth Times
Most volcanic activity occurs at plate boundaries, but there are also a large number of These areas of so-called intraplate volcanism are called hot spots. landscapes and phenomena taken during volcano tours over the past few years. The Wikibook Historical Geology has a page on the topic of: Hotspots (): Moving hotspots – Evidence from paleomagnetism. Magma generated by the hot spot rises through the rigid plates of the lithosphere and As oceanic volcanoes move away from the hot spot, they cool and subside , Hot spots are places within the mantle where rocks melt to generate magma.
These plumes of incredibly hot, molten rock push against continental plates and drive their movement. Around 70 million years ago, the tectonic plate that now includes the Indian subcontinent lay northeast of Madagascar. Suddenly, it started moving incredibly quickly - by geological standards - at 10 centimetres per year.
Around the same time, a spate of huge volcanoes occurred at the Deccan Plateau, sited in the area that is now India. Molten lava was thrown over around 1.
Steve Cande and Dave Stegman, who led the study for Scripps Institution of Oceanography, tracked movements of continental plates throughout Earth's history. Their research suggests that the Indian subcontinent tectonic plate sat over a powerful mantle plume which began around 70 million years ago, around what is now the Reunion Islands.
This rising mass of hot rock hit the Earth's crust and spread out. The pushing force of the mantle plume sent the Indian plate hurtling towards what is now Asia.
The Reunion mantle plume is also thought to be responsible for the mass volcanism at the Deccan Plateau.
Hotspot (geology) - Wikipedia
Cande and Stegman also think that the Reunion mantle plume caused the African tectonic plate to slow down for around 5 million years. After the plume subsided, the Indian tectonic plate slowed to a more normal geological movement of around a few centimetres each year, whereas the African plate sped up. Tuzo Wilsonwho postulated in that the formation of the Hawaiian Islands resulted from the slow movement of a tectonic plate across a hot region beneath the surface.
Composition[ edit ] Most hotspot volcanoes are basaltic e. As a result, they are less explosive than subduction zone volcanoes, in which water is trapped under the overriding plate.
Plate tectonics affected by mantle hot spots
Where hotspots occur in continental regionsbasaltic magma rises through the continental crust, which melts to form rhyolites. These rhyolites can form violent eruptions. However, when the rhyolite is completely erupted, it may be followed by eruptions of basaltic magma rising through the same lithospheric fissures cracks in the lithosphere. An example of this activity is the Ilgachuz Range in British Columbia, which was created by an early complex series of trachyte and rhyolite eruptions, and late extrusion of a sequence of basaltic lava flows.
The latter form over subduction zones, at converging plate boundaries.
When one oceanic plate meets another, the denser plate is forced downward into a deep ocean trench. This plate, as it is subducted, releases water into the base of the over-riding plate, and this water mixes with the rock, thus changing its composition causing some rock to melt and rise. It is this that fuels a chain of volcanoes, such as the Aleutian Islandsnear Alaska.
Plate Tectonics: intraplate (hot spot) volcanism / VolcanoDiscovery
Hotspot volcanic chains[ edit ] Over millions of years, the Pacific Plate has moved over the Hawaii hotspotcreating a trail of underwater mountains that stretch across the Pacific Kilauea is the most active shield volcano in the world. The volcano has erupted nonstop since and it is part of the Hawaiian—Emperor seamount chain.
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Mauna Loa is a large shield volcano.