Readers ask: What Is An Andesitic Volcano?

Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesite magma can also generate strong explosive eruptions to form pyroclastic flows and surges and enormous eruption columns.

What causes andesitic volcanoes?

Granitic, or rhyolitic, magmas and andesitic magmas are generated at convergent plate boundaries where the oceanic lithosphere (the outer layer of Earth composed of the crust and upper mantle) is subducted so that its edge is positioned below the edge of the continental plate or another oceanic plate.

What type of volcano has andesitic lava?

Shield volcanoes are formed by basaltic magma, typically above a mantle plume, whereas the stratovolcanoes (sometimes referred to as composite volcanoes) are formed by andesitic/rhyolitic magma.

How are andesite volcanoes formed?

Andesite and diorite are common rocks of the continental crust above subduction zones. They generally form after an oceanic plate melts during its descent into the subduction zone to produce a source of magma. This is because their parent magmas formed from the partial melting of a basaltic oceanic plate.

What is andesite lava?

Andesite lava is of moderate viscosity and forms thick lava flows and domes. The word andesite is derived from the Andes Mountains in South America, where andesite is common. Andesite is the volcanic equivalent of diorite.

What is andesitic composition?

Andesite most commonly denotes fine-grained, usually porphyritic rocks; in composition these correspond roughly to the intrusive igneous rock diorite and consist essentially of andesine (a plagioclase feldspar) and one or more ferromagnesian minerals, such as pyroxene or biotite.

What type of volcano is andesitic magma form?

What type of volcano has andesitic magma? Shield volcanoes are formed by basaltic magma, typically above a mantle plume, whereas the stratovolcanoes (sometimes referred to as composite volcanoes) are formed by andesitic/rhyolitic magma.

What is an example of a volcano with andesitic lava composition?

Andesite commonly erupts from stratovolcanoes, where they form small-volume flows that typically advance only short distances down the flanks of a volcano. The two examples shown here are short andesite flows advancing down the slope of the Lascar volcano in Chile, and the Colima volcano in Mexico.

How is andesitic magma formed?

Andesitic magma is formed through wet partial melting of the mantle. The mantle under the ocean has contact with water. Basaltic magma with a high water content is the result. If this type of basaltic magma melts with continental crust that has a high density of dioxide silicon, andesitic magma will form.

Why do composite volcanoes have andesitic magma?

Composite volcanoes Andesitic magma, which is lower in temperature, has more silica and a lot of dissolved gases and is more likely to explode when it reaches the surface. Acidic lava, which is very viscous (sticky). For this reason, they’re also known as stratovolcanoes. Strato means layers.

Is andesite volcanic or plutonic?

Andesite is a volcanic (=extrusive igneous) rock with an intermediate to high silica content. It is the eruptive equivalent of diorite,- the same magma that produces diorite as an intrusion will become andesite if erupted.

What is basaltic andesitic and rhyolitic?

Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800^oC to 1000^oC (1472^oF to 1832^oF). Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium.

What is the use of andesite?

Andesite may be used as aggregate or fill, but it is not ideal for concrete applications because it is high in silica, and causes alkali-silica reactivity in the concrete. Andesitic volcanism is associated closely with porphyry copper deposits and it is a host rock for much of the world’s copper ore.

How do you identify andesite?

Andesite is usually light to dark gray in colour, due to its content of hornblende or pyroxene minerals. but can exhibit a wide range of shading. Darker andesite can be difficult to distinguish from basalt, but a common rule of thumb, used away from the laboratory, is that andesite has a color index less than 35.

What is the difference between basaltic and andesitic lava?

Both lavas are formed at different plate boundaries which is why they have different silica contents: the basaltic lava forms from the hot mantle material at constructive plate boundaries and hotspots whereas the andesitic lava forms at destructive plate boundaries from melting crust.

What is the characteristics of andesite?

Andesite is a dark, fine-grained, brown or greyish intermediate volcanic rock which is a commonly found in lava. The mineral composition of andesite includes biotite, pyroxene, or amphibole.