Early minerals, such as the chromium-bearing mineral chromite, crystallize early and are denser than the surrounding magma. |
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The size and depth of these magma chambers can be determined by mapping the earthquake activity around them. |
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When magma moves beneath a volcano, such as when the magma chamber fills prior to an eruption, there is swelling of the volcanic cone above. |
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The magmatic fabric of a plutonic rock forms during a relatively short time interval, after ascent and before final crystallization of magma. |
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The deepest layer is gabbro, coarse-grained but chemically equivalent to basalt, which forms when magma cools and crystallizes slowly. |
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What's under threat here is simply civilization, the thin crust we lay across the seething magma of nature, including human nature. |
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This results in boiling and separation of a hydrothermal fluid from the magma. |
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And in the case of magma it can foam and outgas very volatile compounds that can cause explosive eruptions and throw projectiles great distances. |
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Variations in composition within each series reflect differentiation in magma chambers under volcanoes. |
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Once the gas-saturated magma is ponded and retained in a holding reservoir, it will cool and crystallize, causing further degassing. |
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Whatever the source, an alkalic basaltic magma pooled in the potassium-poor rocks of the lower crust. |
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The dominant magma types are basalts and hawaiites, with lesser amounts of trachytes, quartz trachytes, alkali rhyolites and phonolites. |
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The bulk of the T2 magma is represented by the lava domes and coulees, which are the most evolved. |
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When gas from the magma chamber has been exhausted, the lava erupts more quietly to form a broader and lower edifice, a shield volcano. |
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We suggest that primitive magmas ascending from the mantle are normally trapped in magma chamber complexes situated at or near the Moho. |
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The selective removal of these minerals resulted in a change of the composition of the magma to one near that of the rock syenite. |
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Several pools of syenitic magma were separated from the main body of the melt. |
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Increased concentrations of carbon dioxide and hydrogen sulfide were detected in the air, signs of fresh magma rising. |
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Eruptions after 26 October 1986 were phreatic steam explosions, not direct expressions of magma. |
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These eruptions are thought to rise first as vertical sheets of magma, before separating into individual pipes. |
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These estimates of intrusion times may be compared to estimates based on magma supply through dykes. |
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Second, Dan Johnson is overseeing a microgravity experiment designed to measure minute changes in mass as magma moves and vesiculates. |
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If enough magma congealed around the exchangers it could degrade performance and cause damage. |
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Dissolved gases in the magma determine whether the eruption will be explosive or nonexplosive. |
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The viscosity of the magma, however, is also an important factor in determining whether an eruption will be explosive or nonexplosive. |
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As a result, density and viscosity both decrease, and the magma becomes buoyant and mobile. |
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They may be caused by a complex system of faults or by changes in the volcano's magma plumbing system. |
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Volcanoes erupt not simply because magma is hot, but because hot, rising magma turns underground water to steam, which then expands explosively. |
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These sediments are melted and generate magma, which buoys up to earth's surface and erupts explosively at major island arc volcanic systems. |
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As the magma approaches the surface it occasionally erupts and forms volcanoes. |
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Others, called volcanic earthquakes, are usually shallower and can be precursors to volcanic eruptions and intrusions of magma. |
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This, together with volatile exsolution, which creates buoyant magma, allows evolved magma to erupt. |
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Gases that are dissolved in the magma until the time of eruption bubble out as the magma approaches the surface of the Earth. |
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Ascent of magma and construction of volcanoes, however, are not driven by thermal energy but by gravitational energy. |
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Mass balance calculations support this model of cogenesis by differentiation from a common parent magma with at least two cycles. |
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This event is also associated with production of late orogenic granite magma. |
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At this series of erupting geysers in the north of the island, boiling water is expelled from the magma at the earth's core. |
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First, we assume that the magma degassing process is open, meaning that gas and bubbles are lost from the magma during degassing. |
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Faults provide additional pathways, such as dykes, for magma transport and also may help to degas the magma during its ascent. |
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If this happens slowly, the gas bubbles will slowly migrate through the magma and degas. |
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The remaining magma as lava domes and coulees was extruded with some associated subplinian or vulcanian explosive activity. |
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If magma were to accumulate at mid-crustal levels beneath the north Taupo region, this has significant implications for hazard monitoring. |
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Scientists believe that diamonds ascend to the earth's surface in rare molten rock, or magma that originates at great depths. |
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The presence of faults within the edifice of the volcano may influence the transport and degassing of the magma. |
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We estimate the magma production, erosion and marine depositional rates of volcanic products. |
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Massive sulfide deposits may also form in other settings where water circulates in rocks near cooling magma. |
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As old oceanic crust was consumed in the trenches, new magma rose and erupted along the spreading ridges to form new crust. |
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In other words, the magma is squeezed upwards as thin sheets through long, narrow fractures. |
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This magma is rich in carbon dioxide gas, which produces explosive eruptions. |
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In the conduit where the crust cracked, the magma crystallizes and forms a dike. |
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Normally magma would fill the crack and the adjacent plates would inch away by just that amount. |
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The ringmaster then waved his hand and the earth opened up, revealing a vent filled with hot magma. |
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From beneath the dome, the magma could combine with pressurized gases and steam to trigger an eruption, Pierson said. |
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Dolerite is basaltic magma that solidifies rapidly in sills and dikes near the surface. |
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Two years ago the magma was close enough to the crown of the volcano to be seen clearly from the air. |
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Injections of new batches of mafic magma have been important for triggering dacitic eruptions. |
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The frequent but low-level activity of Vesuvius in recent centuries has relieved the build-up of pressure in the magma chamber. |
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As H2O builds up, density and viscosity decrease to a stage where the magma may again be sufficiently buoyant and mobile to rise further. |
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Intrusion of more magma into the chambers renewed doming of the collapsed calderas in an episode of resurgence. |
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A large body of magma, capped by a hydrothermal system, still exists beneath the caldera. |
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This certain spewer of magma had been dead for some time, but it was still hot enough to make any man sweat uncontrollably. |
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Eventually the central location within the volcano was again utilized for magma storage and a deep caldera was produced. |
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The question of why the plates move gets passed on to the geologists, who appeal to an upwelling of magma that pushes them apart. |
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Based on the position of the dikes, where was the source of the magma for the laccoliths located? |
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Individual volcanoes of continental monogenetic volcanic fields are generally presumed to erupt single magma batches during brief eruptions. |
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Because it is less dense than the surrounding mantle, the magma rises toward the surface. |
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The development of extensional and shear fractures in volcanic areas is usually related to magma emplacement at shallow crustal levels. |
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A spectacular form of heat advection occurs when molten rock, or magma, erupts from a volcano. |
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He argued that all other granites represent hybrid magma formed by reaction of basaltic melt with crustal metamorphic rocks. |
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Rising magma continues to build a lava dome in the crater of Mount St. Helens. |
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The low water contents strongly suggest that the erupted tephras were derived from a shallow magma reservoir or reservoirs. |
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The youngest core analysis is of identical age to the interpreted magmatic age and may have recrystallized in the magma. |
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They suggest that liquid in the Martian crust was heated when the molten rock or magma rose to the surface. |
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It further supportis the idea that the magnetic lineations represent the stretching direction of the deforming magma. |
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Lighter than the surrounding solid rock, this liquid magma rises, cools, and crystallizes beneath Earth's surface. |
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Steady rumblings have been recorded indicating the upward movement of magma. |
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A Hawaiian eruption involves the steady supply of fluid, relatively gas-poor magma to the vent. |
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Magmas concentrate metals, and magma fluids traveling into the surrounding wall rock plant the seeds for mineral growth. |
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Crystals of the mineral were then carried in suspension by the upward-moving magma and forced toward the center of the flowing slurry. |
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Prior to any volcanic eruption, magma wells up through the earth's crust via any weaknesses in the rock structure. |
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The magma contains components of the sediments and weathered oceanic crust from the Nazca plate as well as the peridotite in the mantle beneath South America. |
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The enclaves probably represent globules of mafic magma in felsic magma. |
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The injection of a mafic magma into a more silicic magma chamber is an important trigger mechanism in moderate-sized andesitic, dacitic and rhyolitic eruptions. |
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The fault structure was veneered by lava which was produced by the peripheral magma reservoirs and flowed down the scarp and into the lower central caldera. |
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The higher buoyancy will allow the magma to pond at shallower depths. |
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Layered intrusions commonly occur with mafic intrusions where the minerals have a wider range of specific gravity, and the magma viscosity was low. |
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Ocean ridges are linear features on the ocean floor where molten magma originating in the earth's mantle rises and solidifies to form new ocean crust. |
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The hot gases and magma melted the ice and snow that covered the mountain and the resulting mudflow continued throughout the night and the following day. |
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The typical image that this process invokes is that of a magma chamber with bits and pieces of the enclosing country rock or wall rock floating in the magma. |
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Iron-heavy minerals are believed to have sunk through the magma before floating to the surface in a new form of mountain. |
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This suggests that the peralkaline volcanic magma was derived from a lithospheric mantle source that had not been previously depleted in incompatible elements. |
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The simplest explanation is that the general assumption that continental monogenetic volcanic fields lack significant shallow magma storage zones must be in error. |
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Underneath our feet tectonic plates shift, magma bubbles, water boils, and both regularly erupt. |
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Intended to improve the understanding of how these volcanos erupt, the system investigates the dynamics of the entire magma system below the island. |
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Inevitably, where molten rock met the bitter cold of space, heat was lost rapidly, allowing the outermost levels of the magma ocean to solidify to a thin crust. |
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When the volcano blew its top, thousands perished, immolated by fire, boiling magma, and ash. |
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Vulcanites, such as basalt and fire opal, will be formed within erupted magma where cooling is rapid and only tiny crystals have the chance to form. |
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The earthquakes indicate releases of seismic energy and magma movement. |
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Several pools of syenitic magma were separated from the main body of the melt, each eventually being emplaced as quartz syenite, fayalite granite, and riebeckite granite. |
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By this I mean that it might never have actually crystallized from a molten magma but rather recrystallized from some other rock form through a diffusion process. |
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Melts form at the highest temperatures and lowest pressures resulting in large volumes of tholeiitic magma that form shield volcanoes such as Mauna Loa. |
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The inner ear's structure and contents is thought to permit the shark to determine and distinguish sounds and the geomagnetic fields of the earth's magma. |
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A volcanic eruption, or magma rising and cooling close to the Earth's surface, will cause the formation of a wide variety of igneous rock crystals. |
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If the magma has risen quickly from the source region of the volcano, the xenoliths may represent country rock from all levels of the crust through which it has travelled. |
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Until the rocks crystallized, uranium atoms could move freely through the molten magma from which they formed, and decayed uranium could be replenished. |
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Fractionation of ferromagnesian phases such as olivine, pyroxene and magnetite must have taken place during magma emplacement, as is suggested by the low Co abundance. |
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Folded sediments of pink-brown rock rise on either side, broken at intervals by dark basalt columns of solidified magma and occasional leopard caves. |
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An aircraft will soon fly over the lava dome to test for the presence of carbon dioxide and sulfur dioxide, signs that magma might be building up. |
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The gist of the finding is that under the earth, the magma chambers do not consist of molten magma alone, but solid crystals are also found there. |
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If the magma is about 60 percent plagioclase feldspar and 35 percent mafic minerals, the intrusive rock diorite or the extrusive rock andesite will be formed. |
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Geological Survey crews also observed a shift in the crater floor and on part of the 1,000-foot lava dome that essentially serves as a plug for magma, he said. |
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And it all depends on what's happening under the volcano in the magma body under the lava dome, whether this system will continue to repressurize or not. |
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Studies of layering in individual lava flows suggest that rising volatiles may effect mass transfer of complexed ions during differentiation in magma chambers. |
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Large plinian eruptions sometimes result in the withdrawal of so much magma from below a volcano that part of it collapses to form a large depression called a caldera. |
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Like magma seeping up through geological faults, this emotion can explode in unexpected ways. |
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In some cases, rising magma can cool and solidify without reaching the surface. |
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Granitic rocks are microcracked by differential contraction during cooling of the magma. |
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Felsic magma, such as rhyolite, is usually erupted at low temperature and is up to 10,000 times as viscous as basalt. |
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This work can also help to explain processes that occur within the Earth, such as subduction and magma chamber evolution. |
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During magma crystallization, caesium is concentrated in the liquid phase and crystallizes last. |
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Extinct volcanoes are those that scientists consider unlikely to erupt again because the volcano no longer has a magma supply. |
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Volcanic eruptions can also create new islands, as the magma cools and solidifies upon contact with the water. |
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The 'bun' may be the result of what is known on Earth as a laccolith, an intrusion formed by magma pushing up from below. |
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Sills, dykes and related laccoliths are the physical record of the transfer of magma through the upper crust. |
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The presence of water in magma reduces the melting temperature, which may also play a role in enhancing Icelandic volcanism. |
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Then much of the magma was contaminated with crustal materials prior to their eruption. |
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During the explosive process, the Venus breccia formed when the ascending dacite magma reacted with groundwater to produce a phreatic eruption. |
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The magma then extruded outward from a dike to form a volcanic dome over the tuff. |
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As magma cools and solidifies, hydrogen and chlorine present in the molten rock tend to bond to form hydrogen chloride gas. |
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Approximately 40 cinder cones characterize Cima Volcanic Field, where the magma is also of basaltic composition. |
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Mineral compositions vary as magmas evolve in sub-volcanic, lithospheric magma chambers by assimilation and differentiation. |
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Gabbro forms from molten rock, called magma, that rises out of the mantle and hardens deep within the crust. |
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Early-forming apatite is so fluorine-rich that it vacuums all the fluorine out of the magma, followed by chlorine. |
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As the magma cools, REE elements eventually become concentrated in accessory phases such as zircon, rutile, ilmenite, titanite and monazite. |
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As the plates pull apart, molten magma escapes from deeply buried chambers and squits up to the surface, where it flows out and hardens. |
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The magma is likely the uncrystallized portion of a mass that flowed into the chamber dung a 1955 eruption. |
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The copper containing dikes are derived from a larger magma chamber with a similar composition and copper content. |
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Aquamarine typically forms when magma, or melted rock, cools in an underground pocket called a magma chamber. |
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Leg 118 recovered 500 meters of gabbroic rocks that formed in a magma chamber beneath the very slow-spreading Southwest Indian Ridge. |
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The collapse may have been caused by the vertical inflation of deeper magma chambers that fed the volcanoes. |
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Volcanoes are vents that allow molten rock, debris, and gases to be released from the magma chambers. |
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Mungall and colleagues conducted an experiment mimicking how sulfide minerals act in magma chambers. |
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The rocks date back as much as 2,500 million years and were formed in the deep-seated magma chambers far below active volcanoes. |
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The filling of subvolcanic magma chambers is the result of the rate of magma supply and the rate at which room is created by extension. |
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It is believed to represent the frozen remains of magma chambers where lava rising out of the earth's interior pooled deep in the crust. |
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The Pitcairn Islands were formed by a centre of upwelling magma called the Pitcairn hotspot. |
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Igneous rock is formed through the cooling and solidification of magma or lava. |
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The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. |
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When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite. |
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The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. |
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The molten rock, with or without suspended crystals and gas bubbles, is called magma. |
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When magma reaches the surface from beneath water or air, it is called lava. |
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The change of rock composition most responsible for the creation of magma is the addition of water. |
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Increase in temperature is the most typical mechanism for formation of magma within continental crust. |
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Such temperature increases can occur because of the upward intrusion of magma from the mantle. |
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If crystals separate from the melt, then the residual melt will differ in composition from the parent magma. |
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Bowen's reaction series is important for understanding the idealised sequence of fractional crystallisation of a magma. |
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All three types may melt again, and when this happens, new magma is formed, from which an igneous rock may once more crystallize. |
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These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix. |
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Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earth's crust. |
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The chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowen's reaction series. |
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It is also possible that terrestrial planets had magma oceans at some point during their formation as a result of giant impacts. |
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They result from seawater becoming heated after seeping through cracks to places where hot magma is close to the seabed. |
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If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. |
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Fresh unevolved magma injections can remobilise more evolved magmas, allowing eruptions from more viscous magmas. |
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The type of volcano depends on the location of the eruption and the consistency of the magma. |
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These are formed where magma pushes between existing rock, intrusions can be in the form of batholiths, dikes, sills and layered intrusions. |
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The type of rock formed depends on the chemical composition of the magma and how rapidly it cools. |
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Existing rocks that come into contact with magma may be melted and assimilated into the magma. |
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The buoyant melt rises as magma at a linear weakness in the oceanic crust, and emerges as lava, creating new crust upon cooling. |
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New magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earth's mantle. |
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Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. |
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The magma inside the pillow cools slowly, so is slightly coarser grained than the skin, but nevertheless it is still classified as fine grained. |
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The volcanic arc is the surface expression of the magma that is generated by hydrous melting of the mantle above the downgoing slab. |
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This upwelling magma then cools and solidifies by conduction and convection of heat to form new oceanic crust. |
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Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source. |
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The magma opened a route to the surface which erupted for about ten hours, with the plume probably reaching a height of 35 kilometres. |
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This process operates regardless of the origin of the parental magma to the granite, and regardless of its chemistry. |
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The basic idea is that magma will rise through the crust as a single mass through buoyancy. |
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As these narrow conduits open, the first magma to enter solidifies and provides a form of insulation for later magma. |
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The explosive nature of the eruption on April 14 last year was caused by glacial meltwater coming into contact with hot volcanic magma. |
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Individual plutons are solidified from magma that traveled toward the surface from a zone of partial melting near the base of the Earth's crust. |
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Traditionally, these plutons have been considered to form by ascent of relatively buoyant magma in large masses called plutonic diapirs. |
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Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. |
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It is common for magma to explode as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface. |
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Intrusive rock forms within Earth's crust from the crystallization of magma. |
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Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons. |
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A body of intrusive igneous rock which crystallizes from magma cooling underneath the surface of the Earth is called a pluton. |
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This is as the magma cools underground, and while cooling may be fast or slow, cooling is slower than on the surface, so larger crystals grow. |
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When the magma reaches the surface, it often builds a volcanic mountain, such as a shield volcano or a stratovolcano. |
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Around 295 million years ago upwelling magma spread through fissures and between strata in the earlier Carboniferous Limestone country rock. |
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In geology, the term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement and eruption. |
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At a spreading center basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. |
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The eruption of such a huge quantity of magma emptied the magma chamber beneath the volcano and led to the collapse of the overlying rocks to form the caldera. |
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It has long been realized that plutons contain a wealth of information important in unravelling the complex processes that operate in magma chambers. |
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Extrasolar terrestrial planets that are extremely close to their parent star will be tidally locked and so one half of the planet will be a magma ocean. |
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This magma tends to be extremely viscous because of its high silica content, so it often does not attain the surface but cools and solidifies at depth. |
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New magma from deep within the Earth rises easily through these weak zones and eventually erupts along the crest of the ridges to create new oceanic crust. |
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It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. |
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The full magma chamber is equivalent in height to three versions of the Statue of Liberty stacked one on top of the other, with tunnels descending to a depth of 200 metres. |
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In a process called flux melting, water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, thus creating magma. |
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An alternate view is that plutons commonly are formed not by ascent of large magma diapirs, but rather by aggregation of smaller volumes of magma that ascend as dikes. |
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Volcanoes are places where magma reaches the earth's surface. |
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Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and also a greater tendency to form phenocrysts. |
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Basaltic magma is high in iron and magnesium, and has relatively lower aluminium and silica, which taken together reduces the degree of polymerization within the melt. |
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Lava domes are formed by the extrusion of viscous felsic magma. |
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The drilling established that a dynamic magma chamber is present and is responsible for the mixing of geologic units and subsequent related mineralization. |
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The lakes of both Rotorua and Taupo occupy calderas left from enormous prehistoric eruptions, and magma lies at shallow depths beneath a number of centres. |
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Micrographic intergrowths of quartz and K-feldspar are common in the granite associated with comb quartz layers, both of which reflect a significantly undercooled magma. |
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At divergent boundaries, two plates move apart from each other and the space that this creates is filled with new crustal material sourced from molten magma that forms below. |
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And in actual fact, the difference between Northparkes and Mount Adrah is the oxidation state of the magma responsible for the generation of the hydrothermal system. |
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As new oceanic crust is formed, thick sequences of pillow lavas are erupted at the spreading center fed by dykes from the underlying magma chamber. |
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Weaknesses in the Earth's crust created during the Caledonian mountain building phase allowed magma, or molten rock, to flow to the surface through volcanic vents. |
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As the seafloor spreads, magma wells up from the mantle, cools to form new basaltic crust on both sides of the ridge, and is carried away from it by seafloor spreading. |
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This addition of water to the mantle causes partial melting of the mantle, generating magma, which then rises, and which normally results in volcanoes. |
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The lower density magma rises through the crust to the surface. |
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Volcanoes with rhyolitic magma commonly erupt explosively, and rhyolitic lava flows are typically of limited extent and have steep margins, because the magma is so viscous. |
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They are formed by the cooling of molten magma on the earth's surface. |
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Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, forming minerals such as pumice or basalt. |
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However, the composition and origin of the magma that differentiates into granite leaves certain geochemical and mineral evidence as to what the granite's parental rock was. |
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For instance, a magma of gabbroic composition can produce a residual melt of granitic composition if early formed crystals are separated from the magma. |
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Fracture propagation is the mechanism preferred by many geologists as it largely eliminates the major problems of moving a huge mass of magma through cold brittle crust. |
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These rocks are largely igneous in origin, mixed with metamorphosed marble, quartzite and mica schist and intruded by later basaltic dykes and granite magma. |
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Arcs under extension have a steep geothermal gradient and underplating of the crust by mafic magma may transfer sufficient heat to induce anatexis. |
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Magmatic dikes form when magma intrudes into a crack then crystallizes as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. |
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