Magma is a mixture the molten and also semi-molten rock discovered beneath the surface of the Earth.
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Magma is a molten and semi-molten rock mixture uncovered under the surface ar of the Earth. This mixture is usually comprised of four parts: a hot liquid base, called the melt; mineral crystallized through the melt; solid rocks included into the melt indigenous the neighboring confines; and also dissolved gases.
When magma is ejected through a volcano or various other vent, the material is called lava. Magma that has actually cooled right into a solid is called igneous rock.
Magma is very hot—between 700° and also 1,300° Celsius (1,292° and also 2,372° Fahrenheit). This warmth makes magma a really fluid and dynamic substance, able come create brand-new landforms and engage physical and also chemical transformations in a variety of various environments.
Earth is divided into three general layers. The main point is the superheated center, the mantle is the thick, middle layer, and the crust is the optimal layer on which we live.
Magma originates in the lower component of the Earth’s crust and also in the upper part of the mantle. Many of the mantle and also crust room solid, so the existence of magma is crucial to understanding the geology and also morphology the the mantle.
Differences in temperature, pressure, and also structural formations in the mantle and also crust reason magma to type in different ways.
Decompression melting entails the upward motion of Earth"s mostly-solid mantle. This warm material rises come an area of reduced pressure v the process of convection. Areas of reduced pressure constantly have a reduced melting point than locations of high pressure. This reduction in overlying pressure, or decompression, permits the mantle absent to melt and form magma.
Decompression melting often occurs in ~ divergent boundaries, where tectonic key separate. The rifting movement reasons the buoyant magma listed below to rise and fill the an are of lower pressure. The rock climate cools into brand-new crust.
Decompression melting likewise occurs at mantle plumes, columns of warm rock that increase from Earth’s high-pressure core to that lower-pressure crust. When situated beneath the ocean, this plumes, also known as warm spots, push magma top top the seafloor. This volcanic piles can grow into volcanic archipelago over countless years the activity.
Magma can also be created when hot, liquid rock intrudes into Earth’s cold crust. As the fluid rock solidifies, it loser its warmth to the neighboring crust. Much like hot fudge gift poured over cold ice cream, this transfer of warmth is able to melt the surrounding rock (the “ice cream”) right into magma.
Transfer of heat regularly happens at convergent boundaries, where tectonic plates room crashing together. Together the denser tectonic bowl subducts, or sink below, or the less-dense tectonic plate, warm rock from listed below can intrude right into the cooler plate above. This process transfers heat and also creates magma. Over countless years, the magma in this subduction ar can develop a series of energetic volcanoes well-known as a volcano arc.
Flux melt occurs as soon as water or carbon dioxide are added to rock. This compounds reason the absent to melt at lower temperatures. This create magma in areas where that originally preserved a hard structure.
Much like warmth transfer, flux melting also occurs around subduction zones. In this case, water overlying the subducting seafloor would reduced the melting temperature of the mantle, generating magma that rises come the surface.
Magma leaves the confines of the top mantle and crust in two major ways: together an intrusion or together an extrusion. An intrusion can kind features such as dikes and also xenoliths. One extrusion could include lava and also volcanic rock.
Magma have the right to intrude into a low-density area of an additional geologic formation, such together a sedimentary rock structure. As soon as it cools to solid rock, this intrusion is often referred to as a pluton. A pluton is an intrusion of magma that wells increase from listed below the surface.
Plutons can incorporate dikes and also xenoliths. A magmatic dike is merely a huge slab that magmatic product that has actually intruded into one more rock body. A xenolith is a item of absent trapped in another form of rock. Many xenoliths are crystals take it from within the Earth and embedded in magma while the magma to be cooling.
The most familiar means for magma to escape, or extrude, come Earth’s surface is v lava. Lava eruptions deserve to be “fire fountains” of fluid rock or thick, slow-moving rivers of molten material. Lava cools to kind volcanic rock and volcanic glass.
Magma can likewise extrude right into Earth’s setting as part of a violent volcano explosion. This magma solidifies in the air to form volcanic rock called tephra. In the atmosphere, tephra is an ext often called volcanic ash. Together it drops to Earth, tephra contains rocks such together pumice.
In areas where temperature, pressure, and also structural formation allow, magma can collect in magma chambers. Many magma chambers sit much beneath the surface ar of the Earth.
The pool of magma in a magma room is layered. The least-dense magma rises to the top. The densest magma sinks near the bottom the the chamber. Over countless years, many magma chambers just cool to kind a pluton or large igneous intrusion.
If a magma room encounters an massive amount of pressure, however, it may fracture the rock approximately it. The cracks, called fissures or vents, space tell-tale indicators of a volcano. Many volcanoes sit end magma chambers.
As a volcano’s magma chamber experiences better pressure, regularly due to much more magma seeping into the chamber, the volcano might undergo an eruption. One eruption to reduce the push inside the magma chamber. As lengthy as much more magma pools right into a volcano’s magma chamber, over there is the opportunity of an eruption and also the volcano will remain active.
Large eruptions can practically empty the magma chamber. The layers of magma may be documented by the type of eruption material the volcano emits. Gases, ash, and light-colored rock space emitted first, indigenous the least-dense, top layer the the magma chamber. Dark, thick volcanic rock from the lower part of the magma chamber might be exit later.
In violent eruptions, the volume of magma shrinks so much that the whole magma room collapses and forms a caldera.
All magma contains gases and also a mixture of an easy elements. Being that oxygen and also silicon are the many abundant facets in magma, geologists define magma species in regards to their silica content, expressed as SiO2. These distinctions in chemical composition are straight related to differences in gas content, temperature, and viscosity.
Mafic magma has reasonably low silica content, approximately 50%, and greater contents in iron and also magnesium. This form of magma has a low gas content and also low viscosity, or resistance come flow. Mafic magma likewise has high mean temperatures, between 1000o and 2000o Celsius (1832o and 3632o Fahrenheit), i m sorry contributes come its reduced viscosity.
Low viscosity means that mafic magma is the most fluid of magma types. That erupts non-explosively and also moves an extremely quickly as soon as it reaches Earth’s surface ar as lava. This lava cools into basalt, a rock the is heavy and dark in color due to its greater iron and also magnesium levels. Basalt is one of the most common rocks in Earth’s crust and also the volcano islands produced by hot spots. The Hawaiian Islands space a direct result of mafic magma eruptions. Steady and fairly calm “lava fountains” continue to adjust and increase the “Big Island” that Hawaii.
Intermediate magma has greater silica content (roughly 60%) 보다 mafic magma. This outcomes in a greater gas content and viscosity. Its typical temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit).
As a result of its greater viscosity and also gas content, intermediary magma build up pressure listed below the Earth’s surface before it deserve to be released as lava. This much more gaseous and also sticky lava has tendency to explode violently and cools together andesite rock. Intermediate magma most typically transforms into andesite as result of the deliver of warm at convergent bowl boundaries. Andesitic rocks space often uncovered at continent volcanic arcs, such together the Andes mountains in south America, after which they room named.
Felsic magma has the greatest silica content of all magma types, in between 65-70%. Together a result, felsic magma likewise has the highest gas content and also viscosity, and also lowest median temperatures, between 650o and also 800o Celsius (1202o and also 1472o Fahrenheit).
Thick, viscous felsic magma have the right to trap gas balloon in a volcano’s magma chamber. These trapped balloon can cause explosive and destructive eruptions. This eruptions eject lava violently into the air, i beg your pardon cools right into dacite and rhyolite rock. Lot like intermediate magma, felsic magma might be most typically found in ~ convergent plate boundaries where transfer of heat and flux melting create large stratovolcanoes.
Magma exists together pockets and also plumes in ~ the surface of the Earth.
Photograph through Carsten Peter, nationwide Geographic
Magma is commonly studied as lava or igneous rock. But most magma stays molten or partially molten beneath Earth’s surface. In fact, magma has actually only been discovered three times in that is “natural” habitat deep in Earth’s crust. Geothermal drilling projects discovered two magma web page on the “Big Island” the Hawaii, and one on Iceland.
In 2009, the iceland Deep Drilling Project produced a well that supplies magma to create geothermal energy. Normally, geothermal energy is developed by pump water into hot volcanic bedrock, creating heavy steam that is then harnessed to generate electricity. While common geothermal sources average approximately 60° come 80°Celsius (140° to 176° Fahrenheit), the magma well’s steam reached a record-breaking temperature that 450° Celsius (842° Fahrenheit)! This huge increase in temperature permitted just one magma fine to generate about 36 megawatts the electricity, powering 36,000 homes. In comparison, one solitary wind generator generates in between 1 to 3 megawatts.
Hawaii"s Molten MagmaHawaiian magma is different than magma in various other parts the the Earth due to the fact that it has an ext molten rock and less liquified gases and also rock fragments. The Hawaiian volcano Kilauea, on the "Big Island" the Hawaii, has erupted with enough molten lava come pave a road roughly the earth three times.
type the mineral the is clean and, when viewed under a microscope, has a repeating sample of atoms and also molecules.
upward activity of Earth"s mantle to an area of reduced pressure, permitting mantle rock to melt, bring about magma formation.
area where 2 or much more tectonic key are moving away from every other. Additionally called one extensional boundary.
process the occurs once water is included to hot, heavy rock, lowering that melting suggest and permitting the creation of magma.
state of issue with no fixed form that will fill any kind of container uniformly. Gas molecules space in constant, random motion.
study of the physical background of the Earth, that is composition, that structure, and also the procedures that form and readjust it.
intensely hot an ar deep in ~ the earth that rises to just underneath the surface. Some hot spots produce volcanoes.
phenomenon whereby lava is forcefully yet not violently ejected from a volcano through a fissure or vent.
massive slab of heavy rock comprised of Earth"s lithosphere (crust and also upper mantle). Likewise called lithospheric plate.
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an opened in the Earth"s crust, v which lava, ash, and also gases erupt, and likewise the cone constructed by eruptions.
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