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Rhyolite. Rhyolite (/ ˈraɪ.əlaɪt / RY-ə-lyte) [1][2][3][4] is the most silica -rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and ...
Magmatic water. Magmatic water, also known as juvenile water, is an aqueous phase in equilibrium with minerals that have been dissolved by magma deep within the Earth's crust and is released to the atmosphere during a volcanic eruption. It plays a key role in assessing the crystallization of igneous rocks, particularly silicates, as well as the ...
A chain of volcanoes is created as the lithosphere moves over the source of magma. In geology, hotspots (or hot spots) are volcanic locales thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. [1] Examples include the Hawaii, Iceland, and Yellowstone hotspots. A hotspot's position on the Earth's ...
Eruption. Oruanui eruption impact North Island in terms of approximate 10cm ash deposit (white shading) and approximate ignimbrite from pyroclastic flow (yellow shading). [2]: 529 The central red area is the Oruanui caldera with surrounding collapse crater in lighter red. It is superimposed on present day New Zealand although at the time New ...
Dacite (/ ˈdeɪsaɪt /) is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz.
June 1951 (Rotomahana) June to August 1886 (Tarawera) Mount Tarawera is a volcano on the North Island of New Zealand within the older but volcanically productive Ōkataina Caldera. Located 24 kilometres southeast of Rotorua, it consists of a series of rhyolitic lava domes that were fissured down the middle by an explosive basaltic eruption in 1886.
Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass, it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disordered array of liquid. [1] Volcanic glass may refer to the interstitial material, or matrix, in an aphanitic (fine ...
Torfajökull (Icelandic for "Torfi's glacier "; Icelandic pronunciation: [ˈtʰɔrvaˌjœːkʏtl̥] ⓘ) is a rhyolitic stratovolcano, with a large caldera (central volcano) capped by a glacier of the same name and associated with a complex of subglacial volcanoes. Torfajökull last erupted in 1477 and consists of the largest area of silicic ...