What is andesitic magma?

Asked By: Sharmin Imloul | Last Updated: 24th March, 2020
Category: science geology
4.8/5 (58 Views . 43 Votes)
Andesitic magma is mostly produced by stratovolcanoes. It is a type of magma that hardens quickly once it reaches the surface.

Click to see full answer


In this regard, what is andesitic lava?

ANDESITIC LAVA These viscous lavas have relatively high aspect ratios (thickness/area), generally > 1/100, and some are thick enough to form as lava domes. Andesite commonly erupts from stratovolcanoes, where they form small-volume flows that typically advance only short distances down the flanks of a volcano.

Beside above, what are the characteristics of andesitic magma? Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800oC to 1000oC (1472oF to 1832oF). Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium. It occurs in the temperature range of about 650oC to 800oC (1202oF to 1472oF).

Subsequently, one may also ask, how is andesitic magma formed?

Andesitic Magma. Andesitic magma is formed through wet partial melting of the mantle. The mantle under the ocean has contact with water. When subduction, or continental plates pulling away from one another, occurs, the mantle will heat up and water is pushed into it.

Where is andesitic magma found?

generation. 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.

37 Related Question Answers Found

Is aa lava faster than pahoehoe?

The A'a / Pahoehoe difference:
If lava cools slowly and does not move too fast it forms smooth ropy lava called pahoehoe. However, if it cools quickly and moves fast it can tear into clinkery pieces called a'a. Temperature and gases certainly influence whether the lava becomes aa or pahoehoe.

Is andesitic magma an explosive?

Explosive eruptions are favored by high gas content and high viscosity (andesitic to rhyolitic magmas). Explosive bursting of bubbles will fragment the magma into clots of liquid that will cool as they fall through the air.

Where are the different types of magma generated?

Three general types are recognized:
  • Basaltic magma -- SiO2 45-55 wt%, high in Fe, Mg, Ca, low in K, Na.
  • Andesitic magma -- SiO2 55-65 wt%, intermediate. in Fe, Mg, Ca, Na, K.
  • Rhyolitic magma -- SiO2 65-75%, low in Fe, Mg, Ca, high in K, Na.

What is magma made of?

Magma is a molten and semi-molten rock mixture found under the surface of the Earth. This mixture is usually made up of four parts: a hot liquid base, called the melt; minerals crystallized by the melt; solid rocks incorporated into the melt from the surrounding confines; and dissolved gases.

Which type of magma is more explosive?


As a general rule, therefore, nonexplosive eruptions are typical of basaltic-to-andesitic magmas which have low viscosities and low gas contents, whereas explosive eruptions are typical of andesitic-to-rhyolitic magmas which have high viscosities and high gas contents.

How is rhyolite formed?

Rhyolite is a volcanic rock. It is fine-grained because it forms by the rapid cooling of magma, usually when it erupts onto the Earth's surface. When rhyolite erupts quietly it forms lava flows. If it erupts explosively it often forms pumice.

What does basaltic mean?

Scientific definitions for basaltic
A dark, fine-grained, igneous rock consisting mostly of plagioclase feldspar and pyroxene, and sometimes olivine. Basalt makes up most of the ocean floor and is the most common type of lava.

Where is rhyolite found?

Rhyolite is found in volcanic arcs where crustal rocks have been subducted under continental crust and melted into a lighter magma rich in silica.

Is Lava wet?

The rocks over which it flows are technically wet with lava. So yes, technically lava is wet, even though we wouldn't normally use the word “wet” in that way. The lava, itself (when liquid) is very much above the boiling point of water, so it is not wet with liquid water, so it's a no in that sense.

What are three ways that magma is generated?


Three ways to Generate Magmas
Lowering the melting temperature can be achieved by adding water or Carbon Dioxide (flux melting). Decompression Melting - Under normal conditions the temperature in the Earth, shown by the geothermal gradient, is lower than the beginning of melting of the mantle.

What is basaltic magma?

Basaltic lava, or mafic lava, is molten rock enriched in iron and magnesium and depleted in silica. Basaltic magmas are formed by exceeding the melting point of the mantle either by adding heat, changing its composition, or decreasing its pressure. Underwater, basaltic lavas are erupted as pillow basalts.

Why does magma rise after forming?

Magma forms from partial melting of mantle rocks. They may collect in a magma chamber or they may just come straight up. As they rise, gas molecules in the magma come out of solution and form bubbles and as the bubbles rise they expand.

What types of magma are there?

Types of magma are determined by chemical composition of the magma. Three general types are recognized: Basaltic magma -- SiO2 45-55 wt%, high in Fe, Mg, Ca, low in K, Na.

Temperature of Magmas
  • Basaltic magma - 1000 to 1200oC.
  • Andesitic magma - 800 to 1000oC.
  • Rhyolitic magma - 650 to 800oC.

What are two ways primary magma can be generated?

Answer: Primary magmas can be generated through decompression melting at mid-ocean ridges or when water dehydrated from a subducting plate promotes partial melting.

Is Magma a lava?


Magma is composed of molten rock and is stored in the Earth's crust. Lava is magma that reaches the surface of our planet through a volcano vent.

What kind of volcanoes does andesitic magma produce?

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. You will also come to understand the relationship between volcanic phenomena and plate tectonics.

What are the 4 types of lava?

The most common way to divide lava flows into distinct types is following: Pahoehoe lava flow, Aa lava flow, Blocky lava flow, and also Pillow lava flow.