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Andesite (/ ˈ æ n d ə z aɪ t /) [1] is a volcanic rock of intermediate composition.In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite.
The andesite line is the most significant regional geologic distinction in the Pacific Ocean basin. It separates the mafic basaltic volcanic rocks of the Central Pacific Basin from the partially submerged continental areas of more felsic andesitic volcanic rock on its margins.
Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase . Basaltic andesite can be found in volcanoes around the world, including in Central America [ 1 ] and the Andes of South America .
A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm. Adakite – Volcanic rock type; Andesite – Type of volcanic rock; Alkali feldspar granite – Type of igneous rock rich in alkali feldspar; Anorthosite – Mafic intrusive igneous rock composed predominantly of plagioclase
The Bearwallow Mountain Andesite or Bearwallow Mountain Formation is a geologic formation exposed in and around the Mogollon Mountains of southwest New Mexico. It has a radiometric age of 27 to 23 million years, corresponding to the late Oligocene to early Miocene epochs .
Because andesite is the main type of lava erupted from Mount Price, lava flows are a low to moderate hazard. [19] Andesite is intermediate in silica content, indicating it has a higher viscosity than basaltic lava but is less viscous than dacite or rhyolite lava. As a result, andesite lava flows typically move slower than basaltic lava flows ...
Along the rim of the Pacific Basin are convergent plate boundaries often referred to as the andesite line since orogenic andesite is associated with this boundary. This line is often, but erroneously, confused with the boundaries of either the Pacific plate or the Pacific basin; the andesite line, however, also includes the Juan de Fuca, Cocos ...
9- to 18-million-year-old basalt, basaltic andesite, and andesite lavas with lesser amounts of dacite tuffs and lavas. [2] 18- to 40-million-year-old silicic tuffs and lavas. Units 3 and 4 were erupted from many vents west of known High Cascade volcanic centers, although some of these older vents may be buried beneath the High Cascade Range. [2]