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QAPF diagram with basalt/andesite field highlighted in yellow. Andesite is distinguished from basalt by SiO 2 > 52%. Andesite is field O2 in the TAS classification.. Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals.
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.
Composite or stratovolcanoes often have andesitic magma and typically form the extrusive rock andesite. Andesitic magma is composed of many gases and melted mantle rocks. [2] Cinder or scoria cones violently expel lava with high gas content, [2] and due to the vapor bubbles in this mafic lava, the extrusive basalt scoria is formed. [6]
For example, andesitic magmatism is associated with the formation of island arcs at convergent plate boundaries while basaltic magmatism is found at mid-ocean ridges during sea-floor spreading at divergent plate boundaries. On Earth, magma forms by partial melting of silicate rocks either in the mantle, continental or oceanic crust. Evidence ...
Andesitic tuffs are exceedingly common. They occur along the whole chain of the Cordilleras [ 40 ] [ 41 ] and Andes , [ 42 ] in the West Indies , New Zealand, [ 43 ] Japan, [ 44 ] etc. In the Lake District , [ 45 ] North Wales, Lorne , the Pentland Hills , the Cheviots , and many other districts of Great Britain , ancient rocks of exactly ...
Meaning Origin language and etymology Example(s) bacillus: rod-shaped Latin baculus, stick Bacillus anthracis: bacteri-Pertaining to bacteria: Latin bacterium; Greek βακτήριον (baktḗrion), small staff bacteriophage, bactericide: balan-of the glans penis or glans clitoridis: Greek βάλανος (bálanos), acorn, glans balanitis: bas-
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Dacite from the Lassen Volcano National Park. Dacite (/ ˈ d eɪ s aɪ t /) is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides.