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The narrow vertical conduit, postulated to connect the plume head to the core-mantle boundary, is viewed as providing a continuous supply of magma to a hotspot. As the overlying tectonic plate moves over this hotspot, the eruption of magma from the fixed plume onto the surface is expected to form a chain of volcanoes that parallels plate motion ...
Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') [1] is the molten or semi-molten natural material from which all igneous rocks are formed. [2] Magma (sometimes colloquially but incorrectly referred to as lava) is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial ...
Volcanic ash is formed during explosive volcanic eruptions and phreatomagmatic eruptions, [2] and may also be formed during transport in pyroclastic density currents. [3] Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles (dominantly water and carbon dioxide) to exsolve into gas bubbles. [4]
These rhyolites can form violent eruptions. [10] [11] For example, the Yellowstone Caldera was formed by some of the most powerful volcanic explosions in geologic history. 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).
Artemis Corona is a large plume formed by the upwelling of mantle derived magma and is on a scale potentially comparable to that in the Archean mantle. [1] Models using its known characteristics showed that continued magmatism from conductive heat through the plume caused gravitational collapse.
Phreatomagmatic ash is formed by the same mechanisms across a wide range of compositions, basic and acidic. Blocky and equant clasts with low vesicle content are formed. [2] The deposits of phreatomagmatic explosive eruptions are also considered to be better sorted and finer grained than the deposits of magmatic eruption.
Diapirs also form in the Earth's mantle when a sufficient mass of hot, less dense magma assembles. Diapirism in the mantle is thought to be associated with the development of large igneous provinces and some mantle plumes. Explosive, hot volatile rich magma or volcanic eruptions are referred to generally as diatremes. Diatremes are not usually ...
Eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra. The ash and tephra are ejected at speeds of several hundred metres per second, and can rise rapidly to heights of several kilometres, lifted by enormous ...