Magma is described as the extremely hot liquid or the semi-liquid rock which is situated under the Earth's surface. This magma can easily push through the holes or the cracks in the crust surface which causes a volcanic eruption. When the magma flows or it erupts onto the Earth's surface, this is given a new name called lava. Like a solid rock that has many constituents, magma is also a mixture of many minerals.
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Magma, the word has originated from ancient Greek which means ‘thick unguent’. This is a molten or semi-molten material that is of course naturally produced. They also form the igneous rocks in this process. In another study, it is proved that the magma which is found underneath the earth’s surface has magmatism that is similar to be found on other terrestrial planets and other natural satellites. Apart from molten rock, this magma may also contain suspended crystals and gas bubbles.
Magma is molten or half molten rock that also forms igneous rocks. These magma rocks consist of silicate liquid. The magma tricks at the depth of the earth’s surface which is afterwards ejected in the form of lava. The suspended crystals and the fragments of unmelted rock may also be transported in the magma; this is also dissolved and with high volatility may get separated as bubbles and some liquid may also get crystallized during this movement. Other such intertwined physical properties are also responsible to determine the characteristics of magma. This will also lead to describe the chemical composition of the magma, viscosity of the magma, the dissolved gases in the magma, and its temperature.
Molten Magma mostly exists in the lower part of the Earth's crust and also in the upper portion of the mantle. So, the mantle and the crust are solid, and hence the presence of magma is quite crucial to the understanding of the geology and the morphology of the mantle.
Magma here forms from the partial melting of the mantle rocks. As these rocks move upward (or they have water as added to them), they begin to melt a little bit. These then melt and migrate upward and form larger volumes that continue to swim upward. They also may collect in the magma chamber. Also, they might just come straight up.
While they rise, the molecules of gas present in the magma come out of this solution and form bubbles and as these bubbles rise, they gradually expand. After which the pressure of bubbles becomes stronger than the surrounding solid rock and then this surrounding rock fractures, which allows the magma to get to the surface of it.
Magma and Lava
We use the term ‘magma’ which means underground molten rock and we also use the term ‘lava’ for the molten rock which breaks through the Earth's surface.
The accurate distinction between magma and lava is about its location. When we refer to magma, we indicate the molten rock which is being trapped underground. While, when the molten rock comes up to the surface this keeps flowing like a liquid, and then this is called the lava.
Magma is hotter than lava. The hotness actually depends on when the lava has reached the surface and also if the magma and the lava emit from the same magma chamber.
Basaltic lava, also known as the mafic lava, is the molten rock that is enriched in iron and magnesium with depleted in silica. The basaltic magmas are formed by exceeding the melting point of the mantle that is either by adding the heat or changing its composition or by decreasing its pressure.
Basaltic magma is also formed through the dry partial melting of the mantle. The mantle lies quite below the crust of the earth. The Basalts also make up most of the crust of the ocean, thus the basaltic magma is generally found in the oceanic volcanoes.
Types of Magma
There are three types of magma: basaltic, andesitic, and rhyolitic. All of these has a different mineral composition. All this type of magma has a significant percentage of silicon dioxide.
Basaltic magma is high in iron, magnesium, and calcium but it has deficient or it is low in potassium and sodium.
Andesitic magma has adequate amounts of all these minerals.
Rhyolitic magma is high in potassium and sodium while it is low in iron, magnesium, and calcium.
Andesitic magma has moderate amounts of minerals, with a rising temperature that ranges from about 800oC to 1000oC. The Rhyolitic magma is quite high in potassium and sodium but it is low in iron, magnesium, and calcium.
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These are the molten rock inside the earth, they are deeper in the Earth’s surface are hot rocks that slowly melt and this becomes a thick flowing substance which is called magma. Since this is lighter than the solid rock that is around it the magma rises and then collects in magma chambers. Thus, in this process, some of the magma pushes through vents and fissures coming down to the Earth's surface.