What are the composition of magma?
Magmas can vary widely in composition, but in general they are made up of only eight elements; in order of importance: oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, and potassium (Figure 3.2. 1).
What causes the composition of the magma to change?
Fractional Crystallization – When magma crystallizes it does so over a range of temperature. Each mineral begins to crystallize at a different temperature, and if these minerals are somehow removed from the liquid, the liquid composition will change.
How does magma become felsic?
2) If as a magma is cooling, the crystallizing minerals are removed (by settling out of the liquid, or by pressure squeezing the liquid away), then these minerals will deplete the system in those elements that are concentrated in mafic minerals. Thus the magma becomes more felsic in composition.
Why does partial melting result in a magma having a composition different from the rock from which it was derived?
Why does magma composition change during fractional crystallization? Different elements in the magma form crystals at different rates, leaving behind more of the unused elements.
What is the most composition of magma?
There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium.
Which component of magma is the highest and lowest in value?
Felsic MagmaFelsic magma has the highest silica content of all magma types, between 65-70%. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650o and 800o Celsius (1202o and 1472o Fahrenheit).
How do temperature and composition of magma affect viscosity?
Viscosity of Magmas Lower temperature magmas have higher viscosity than higher temperature magmas (viscosity decreases with increasing temperature of the magma).
Which component of magma is the highest and the lowest in value?
Felsic MagmaFelsic magma has the highest silica content of all magma types, between 65-70%. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650o and 800o Celsius (1202o and 1472o Fahrenheit).
Is magma felsic or mafic?
| MAGMA COMPARISON | ||
|---|---|---|
| Property | Mafic Magma | Felsic Magma |
| Composition | iron, magnesium | silica, aluminum |
| Color | darker | lighter |
| Density | higher (3 g/cm3) | lower (2.7 g/cm3) |
What is the composition of felsic?
Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).
Which type of magma forms from the partial melting of continental crust and is low in iron?
Rhyolitic magma forms as a result of wet melting of continental crust.
Does partial melting produces magma with the same composition as the parent rock from which it was derived?
Does partial melting produce magma with the same composition as the parent rock from which it was derived? Because the proportions ( of chemicals) are different as far as composition. No magma formed by partial melting is more felsic than the rock it is originally produced from.
Do lower temperature magmas have higher viscosity?
Lower temperature magmas have higher viscosity than higher temperature magmas (viscosity decreases with increasing temperature of the magma).
What is the composition of the melt generated by partial mantle melting?
Partial melting of mantle rocks will always produce magmas of basaltic composition. Partial melting of subducted ocean crust (basalt) will always produce magmas of andesitic composition. Partial melting of lower continental crust (on average of andesitic composition) will always produce magmas of granitic composition.
What are the common compositions among the three types of magma?
There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium.
What are the composition of magma that can affect its viscosity?
Mafic magmas are low in silica and contain more dark, magnesium- and iron-rich mafic minerals, such as olivine and pyroxene. Felsic magmas are higher in silica and contain lighter colored minerals such as quartz and orthoclase feldspar. The higher the amount of silica in the magma, the higher is its viscosity.
What is felsic magma?
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.
What is mafic and felsic?
Either in describing rocks or lava, mafic means that the lava or rock has less silica while felsic implies that the lava or rock has the most silica.
What is mafic magma?
Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2).
How is andesitic magma formed?
generation. 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 is the melt of a magma composed 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.
What is the difference between felsic and mafic magma?
Either in describing rocks or lava, mafic means that the lava or rock has less silica while felsic implies that the lava or rock has the most silica.
What type of magma is felsic?
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.
What is andesitic composition?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
Where is felsic magma formed?
subduction zone A. Intermediate and felsic magmas form around convergent margins with a subduction zone. 3. these volcanic mountain chains often form arc shapes, because that is the shape produced when a flat plate (tectonic plate) intersects a sphere (Earth).
What does andesitic magma produce?
Andesite magma commonly erupts from stratovolcanoes as thick lava flows, some reaching several km in length. Andesite magma can also generate strong explosive eruptions to form pyroclastic flows and surges and enormous eruption columns. Andesites erupt at temperatures between 900 and 1100 ° C.
Where are andesitic magmas produced?
They have a mineral composition that is intermediate between granite and basalt. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates.
Which of the following compositions would result in a magma with high viscosity?
2. Composition (silica content): the more mafic the lava (less silica) the lower the viscosity; the more felsic the lava (more silica) the higher the viscosity.