Magma is a mixture of molten and semi-molten rock uncovered beneath the surface of the Earth.
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Magma is a molten and also semi-molten absent mixture found under the surface of the Earth. This mixture is usually made up of 4 parts: a hot liquid base, called the melt; minerals crystallized by the melt; hard rocks incorporated into the melt from the bordering confines; and dissolved gases.
When magma is ejected by a volcano or other vent, the product is dubbed lava. Magma that has actually cooled right into a solid is dubbed igneous rock.
Magma is exceptionally hot—between 700° and 1,300° Celsius (1,292° and also 2,372° Fahrenheit). This heat makes magma a very fluid and also dynamic substance, able to create brand-new landforms and also engage physical and also chemical transformations in a variety of different environments.
Earth is split into three basic layers. The main point is the superheated center, the mantle is the thick, middle layer, and also the crust is the height layer ~ above which us live.
Magma originates in the lower component of the Earth’s crust and in the upper portion of the mantle. Many of the mantle and crust room solid, for this reason the visibility of magma is an important to understanding the geology and morphology the the mantle.
Differences in temperature, pressure, and structural formations in the mantle and crust reason magma to form in different ways.
Decompression melting involves the upward motion of Earth"s mostly-solid mantle. This warm material rises to an area of lower pressure through the process of convection. Areas of reduced pressure always have a reduced melting suggest than areas of high pressure. This reduction in overlying pressure, or decompression, allows the mantle rock to melt and form magma.
Decompression melting frequently occurs in ~ divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma listed below to rise and fill the an are of reduced pressure. The rock then cools into brand-new crust.
Decompression melting likewise occurs in ~ mantle plumes, columns of hot rock that increase from Earth’s high-pressure main point to its lower-pressure crust. When located beneath the ocean, these plumes, additionally known as hot spots, press magma onto the seafloor. This volcanic piles can prosper into volcanic islands over numerous years that activity.
Magma can additionally be produced when hot, liquid rock intrudes right into Earth’s cold crust. Together the liquid rock solidifies, it loser its warmth to the surrounding crust. Much like hot fudge being poured end cold ice cream cream, this transport of warmth is able to melt the bordering rock (the “ice cream”) into magma.
Transfer that heat frequently happens in ~ convergent boundaries, wherein tectonic plates room crashing together. Together the denser tectonic key subducts, or sink below, or the less-dense tectonic plate, warm rock from below can intrude right into the cooler plate above. This process transfers heat and also creates magma. Over numerous years, the magma in this subduction zone can develop a collection of energetic volcanoes known as a volcano arc.
Flux melting occurs once water or carbon dioxide are added to rock. This compounds reason the absent to melt at reduced temperatures. This create magma in areas where it originally preserved a hard structure.
Much like warm transfer, flux melting likewise occurs around subduction zones. In this case, water overlying the subducting seafloor would reduced the melt temperature the the mantle, generating magma the rises come the surface.
Magma leaves the confines of the upper mantle and also crust in two major ways: together an intrusion or together an extrusion. One intrusion can form features such as dikes and also xenoliths. One extrusion can include lava and also volcanic rock.
Magma have the right to intrude into a low-density area of one more geologic formation, such together a sedimentary rock structure. Once it cools to solid rock, this intrusion is often called a pluton. A pluton is one intrusion the magma the wells increase from below the surface.
Plutons can encompass dikes and also xenoliths. A magmatic dike is just a big slab of magmatic product that has intruded into an additional rock body. A xenolith is a piece of absent trapped in another type of rock. Many xenoliths space crystals torn from within the Earth and also embedded in magma if the magma was cooling.
The most familiar way for magma to escape, or extrude, come Earth’s surface ar is through lava. Lava eruptions have the right to be “fire fountains” of liquid rock or thick, slow-moving rivers that molten material. Lava cools to form volcanic rock and volcanic glass.
Magma can also extrude right into Earth’s setting as part of a violent volcanic explosion. This magma solidifies in the wait to type volcanic rock dubbed tephra. In the atmosphere, tephra is more often referred to as volcanic ash. As it falls to Earth, tephra has rocks such together pumice.
In locations where temperature, pressure, and structural formation allow, magma have the right to collect in magma chambers. Many magma chambers sit far beneath the surface of the Earth.
The pool of magma in a magma chamber is layered. The least-dense magma rises to the top. The densest magma sinks near the bottom of the chamber. Over countless years, countless magma chambers merely cool to kind a pluton or big igneous intrusion.
If a magma room encounters an huge amount of pressure, however, it might fracture the rock roughly it. The cracks, dubbed fissures or vents, room tell-tale indications of a volcano. Numerous volcanoes sit end magma chambers.
As a volcano’s magma room experiences greater pressure, frequently due to much more magma seeping right into the chamber, the volcano may undergo one eruption. An eruption to reduce the push inside the magma chamber. As lengthy as an ext magma pools into a volcano’s magma chamber, over there is the possibility of one eruption and also the volcano will continue to be active.
Large eruptions can virtually empty the magma chamber. The layers of magma might be recorded by the type of eruption material the volcano emits. Gases, ash, and light-colored rock are emitted first, native the least-dense, optimal layer the the magma chamber. Dark, thick volcanic absent from the lower part of the magma chamber may be released later.
In violent eruptions, the volume of magma shrinks so lot that the whole magma chamber collapses and forms a caldera.
All magma has gases and also a mixture of basic elements. Being that oxygen and also silicon space the most abundant elements in magma, geologists specify magma varieties in terms of their silica content, expressed as SiO2. These distinctions in chemistry composition are straight related to distinctions in gas content, temperature, and also viscosity.
Mafic magma has fairly low silica content, approximately 50%, and greater contents in iron and also magnesium. This kind of magma has a short gas content and low viscosity, or resistance to flow. Mafic magma likewise has high mean temperatures, in between 1000o and 2000o Celsius (1832o and 3632o Fahrenheit), i m sorry contributes to its lower viscosity.
Low viscosity method that mafic magma is the most liquid of magma types. It erupts non-explosively and also moves really quickly once it get Earth’s surface as lava. This lava cools into basalt, a rock the is heavy and also dark in color due come its greater iron and magnesium levels. Basalt is one of the most usual rocks in Earth’s crust as well as the volcano islands created by hot spots. The Hawaiian Islands room a direct an outcome of mafic magma eruptions. Secure and reasonably calm “lava fountains” continue to change and broaden the “Big Island” the Hawaii.
Intermediate magma has greater silica content (roughly 60%) 보다 mafic magma. This outcomes in a higher gas content and viscosity. Its average temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit).
As a result of its higher viscosity and also gas content, intermediate magma build up pressure listed below the Earth’s surface prior to it deserve to be released together lava. This an ext gaseous and sticky lava often tends to explode violently and also cools together andesite rock. Intermediate magma most frequently transforms into andesite as result of the transport of warmth at convergent bowl boundaries. Andesitic rocks room often found at continent volcanic arcs, such together the Andes mountains in southern America, after which they are named.
Felsic magma has the highest possible silica content of every magma types, between 65-70%. Together a result, felsic magma additionally has the highest gas content and viscosity, and lowest average temperatures, between 650o and 800o Celsius (1202o and also 1472o Fahrenheit).
Thick, viscous felsic magma deserve to trap gas balloon in a volcano’s magma chamber. These trapped bubbles can reason explosive and also destructive eruptions. This eruptions eject lava violently right into the air, i m sorry cools into dacite and also rhyolite rock. Much like intermediary magma, felsic magma may be most commonly found at convergent plate limits where deliver of heat and also flux melt create big stratovolcanoes.
Magma exists together pockets and also plumes beneath the surface of the Earth.
Photograph through Carsten Peter, national Geographic
Magma is usually studied as lava or igneous rock. But most magma remains molten or partly molten in ~ Earth’s surface. In fact, magma has actually only been discovered three times in the “natural” habitat deep in Earth’s crust. Geothermal drilling projects found two magma web page on the “Big Island” of Hawaii, and one ~ above Iceland.
In 2009, the iceland Deep Drilling Project developed a fine that offers magma to create geothermal energy. Normally, geothermal energy is developed by pump water into hot volcanic bedrock, creating steam that is then harnessed to create electricity. While normal geothermal resources average approximately 60° to 80°Celsius (140° to 176° Fahrenheit), the magma well’s heavy steam reached a record-breaking temperature of 450° Celsius (842° Fahrenheit)! This large increase in temperature permitted just one magma well to generate approximately 36 megawatts the electricity, powering 36,000 homes. In comparison, one solitary wind wind turbine generates between 1 come 3 megawatts.
Hawaii"s Molten MagmaHawaiian magma is different than magma in various other parts of the Earth since it has more molten rock and less liquified gases and also rock fragments. The Hawaiian volcano Kilauea, top top the "Big Island" that Hawaii, has erupted with sufficient molten lava come pave a road about the earth three times.
type of mineral that is clear and, as soon as viewed under a microscope, has actually a repeating pattern of atoms and also molecules.
upward motion of Earth"s mantle to an area of lower pressure, enabling mantle rock to melt, leading to magma formation.
area where 2 or more tectonic key are relocating away from every other. Also called one extensional boundary.
process the occurs as soon as water is added to hot, solid rock, lowering the melting suggest and allowing the production of magma.
state of issue with no fixed form that will certainly fill any type of container uniformly. Gas molecules room in constant, random motion.
study that the physical history of the Earth, that composition, its structure, and the procedures that type and change it.
intensely hot an ar deep within the planet that rises to just underneath the surface. Some hot spots create volcanoes.
phenomenon where lava is forcefully however not violently ejected native a volcano with a fissure or vent.
massive slab of solid rock comprised of Earth"s lithosphere (crust and also upper mantle). Also called lithospheric plate.
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an opened in the Earth"s crust, through which lava, ash, and also gases erupt, and additionally the cone built by eruptions.
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