How is felsic magma created?
It has been suggested that felsic magmas found at subduction-zone volcanoes are produced by mechanisms including fractional crystallization with or without crustal assimilation8, partial melting of the crust9,10, and partial melting of metasomatised silica-excess pyroxenite mantle11,12.
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 is felsic magma made of?
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.
How are felsic volcanoes formed?
When lava approaches the surface, the pressure on it is greatly reduced and the dissolved gases come out of solution; they form bubbles and rise. The escape of gases may produces tremendous force in a volcano, producing explosive eruptions. In general, the more felsic the magma the greater the volatile content.
Why will magma become more felsic as it ages?
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.
Where is felsic found?
Plutonic and hypabyssal felsic rocks may occur as batholiths, plutons, stocks, laccoliths, dikes, sills and plugs. The largest are granitoid batholiths, which are composite intrusions composed of many individual plutons and associated with active continental margins (see Granite and Granitoids).
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 is the difference between mafic and felsic 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 causes mafic magma?
Such vast outpourings of mafic lava are called flood basalts and are believed to be caused by mantle plumes (hotspots), which partially melt the mantle beneath the earth's crust. The mafic magma that is generated by the mantle plume reaches the earth's surface through fractures (fissures) instead of one central vent.
Why does magma tend to have a more felsic intermediate composition at volcanic sites associated with oceanic continental subduction?
They tend to occur along oceanic-to-oceanic or oceanic-to-continental boundaries because of subduction zones. They tend to be made of felsic to intermediate rock and the viscosity of the lava means that eruptions tend to be explosive.
How are mafic and felsic rocks formed?
0:003:55Igneous Rocks-(Extrusive-Intrusive-Mafic …YouTube
How are felsic magmas different from mafic magmas?
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.
How does mafic magma become felsic?
The processes is called magmatic differentiation by Fractional Crystallization. Because mafic minerals like olivine and pyroxene crystallize first, the process results in removing Mg, Fe, and Ca, and enriching the liquid in silica. Thus crystal fractionation can change a mafic magma into a felsic magma.
How is mafic formed?
Mafic rocks that constitute the igneous oceanic crust are created at mid-ocean ridge seafloor spreading centers as a byproduct of partial melt from upwelling mantle. Through various parts of the spreading process, permeability can be generated in both the intrusive gabbros and extrusive basalts.
Why is a felsic magma much more likely to produce an explosive eruption?
Why is felsic magma much more likely to produce an explosive eruption? . Felsic magma has a high viscosity, which will tend to stick in and clog volcanic conduits.
Why are felsic magmas more viscous than mafic magmas?
Felsic magma has more silica and alumina content, which makes magma more viscous. Mafic magma has less silica content and more iron and magnesium in it.
How is mafic magma formed?
In general, melting of a mantle source (garnet peridotite) results in mafic/basaltic magmas. Melting of crustal sources yields more siliceous magmas. In general more siliceous magmas form by low degrees of partial melting. As the degree of partial melting increases, less siliceous compositions can be generated.
Which of the following describes the way how basaltic magma can generate felsic magma?
Which of the following describes the way how basaltic magma can generate felsic magma? In continental settings, rising basaltic magma can melt low-density silica-rich rocks generating a secondary melt of felsic magma.
How is mafic magma produced?
In general, melting of a mantle source (garnet peridotite) results in mafic/basaltic magmas. Melting of crustal sources yields more siliceous magmas. In general more siliceous magmas form by low degrees of partial melting. As the degree of partial melting increases, less siliceous compositions can be generated.
What is a felsic composition?
Felsic rocks are mostly feldspar (especially K-feldspar), at least 10% quartz, and less than 15% mafic minerals (biotite, hornblende).
Why are felsic magmas more viscous?
First, as we've already discussed, felsic magmas tend to be more viscous because they have more silica, and hence more polymerization. Second, felsic magmas tend to have higher levels of volatiles; that is, components that behave as gases during volcanic eruptions.
What is felsic lava rich in?
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. Viscosity is a liquid's resistance to flow.
Which of the following describes the way how basaltic magma can generate felsic magma quizlet?
Which of the following describes the way how basaltic magma can generate felsic magma? In continental settings, rising basaltic magma can melt low-density silica-rich rocks generating a secondary melt of felsic magma.
Is basaltic magma felsic or mafic?
| Summary Table | ||
|---|---|---|
| Magma Type | Solidified Volcanic Rock | Gas Content |
| Mafic or Basaltic | Basalt | Low |
| Intermediate or Andesitic | Andesite | Intermediate |
| Felsic or Rhyolitic | Rhyolite | High |
Sep 3, 2015
Where is felsic lava found?
convergent zone By contrast, felsic lava is usually found in specific geological areas known as the convergent zone. This area is where geologic plates collide.
What two processes cause initially mafic magmas to become more felsic?
The processes is called magmatic differentiation by Fractional Crystallization. Because mafic minerals like olivine and pyroxene crystallize first, the process results in removing Mg, Fe, and Ca, and enriching the liquid in silica. Thus crystal fractionation can change a mafic magma into a felsic magma.
How do felsic and mafic magma differ?
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.
Where does mafic magma come from?
Mafic magmas are usually produced at spreading centers, and represent material which is newly differentiated from the upper mantle. Common mafic rocks include basalt and gabbro.
Why does a more felsic magma have a higher viscosity than a mafic magma at the same temperature?
Felsic magma has more silica and alumina content, which makes magma more viscous. Mafic magma has less silica content and more iron and magnesium in it.
Why are felsic magma more explosive than mafic magma?
Gases – At depth in the Earth nearly all magmas contain gas. Gas gives magmas their explosive character, because the gas expands as pressure is reduced. Felsic magmas usually have higher gas contents than mafic magmas.