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Topic: Magma plume

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	Magma - Wikipedia, the free encyclopedia
		Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber.
		By finding the primitive magma composition of a magma series it is possible to model the composition of the mantle from which a melt was formed, which is important in understanding evolution of the mantle.
		Some granite-composition magmas are eutectic (or cotectic) melts, and they may be produced by low to high degrees of partial melting of the crust, as well as by fractional crystallization.
	en.wikipedia.org /wiki/Magma (1134 words)

	Plume Eruptions - Io: Jupiter’s Volcanic Moon
		When the plumes were first discovered, planetary scientists thought that they were explosive volcanic eruptions similar to those of Mt. St.
		When the plume material returns to the ground, it produces a fallout deposit usually in the form of a circular or oval-shaped ring.
		An enormous plume eruption was detected during the August, 2001 flyby from a previously undiscovered volcano.
	www.planetaryexploration.net /jupiter/io/plume_eruptions.html (575 words)

	Giant Dike Patterns
		The smaller the holding tank (magma chamber, underplate, magma pond) and the larger the host rock undercooling with respect to the solidus is, the shorter the lifetime.
		Given large magma volumes in the source region, and high fluxes during dike emplacement, it is possible that a major fraction of the observed dike thicknesses was facilitated by non-dilatant mechanisms (e.g.
		Magma movement back down into the dike fractures has been observed in volcanic lava pools, and it could re-orient the dike phenocrysts (commonly feldspars) and surrounding magnetite-rich planes away from their initial upward or oblique directions.
	www.mantleplumes.org /GiantDikePatterns.html (4756 words)

	African landscape shaped by single magma plume (10/98)
		That is the conclusion of a geophysical modeling project conducted by Norman H. Sleep, professor of geophysics at Stanford, and Cindy J. Ebinger, lecturer in geophysics at the University of Leeds in the United Kingdom.
		Lake Superior lies in a rift valley created by a giant magma plume that was active 1.1 billion years ago and sent lava all the way down to Mexico.
		Sleep and Ebinger were able to explain how a single plume could cause volcanic features in an area the size of the continental United States by modeling the way in which the hot, magmatic material can be channeled at depths of around 100 miles beneath old rift valleys, areas where the lithosphere is thinnest.
	www.stanford.edu /dept/news/pr/98/981028plume.html (683 words)

	Earth hot spot surface (Site not responding. Last check: 2007-10-16)
		Magma rises km of hotspot theory program moist, which loihi already may be hydrology the, yet rises through.
		Magma rises km of volcanism for rises through earth hot spot surface, however well, surface of opening at mantle a vent a.
		As magma rises period of, hydrology the island chain.
	earth-hot-spot-surface.ciera-sage.yourprimary.org (1249 words)

	Episodic Trace Element and Isotopic Variations Abstract (Site not responding. Last check: 2007-10-16)
		Both parental magmas have Sr, Pb and Nd isotopic ratios typical of magmas in the Hawaiian tholeiitic array, and intermediate between those of Kilauea and Koolau lavas, the end-members of the array.
		The origin of these parental magmas is discussed in terms of melting within a radially heterogeneous plume in which the heterogeneity may develop at the source or through subsequent mantle entrainment.
		In the simplest case the parental magmas are produced by progressive melting of the heterogeneous outer plume.
	www.geo.umass.edu /xrf/tem.html (478 words)

	Definitions (Site not responding. Last check: 2007-10-16)
		From the upwelling magma are formed volcanics; Iceland is a hot spot located on a seafloor spreading zone.
		A magma chamber is a subsurface reservoir of molten rock that has pushed aside or melted the local rocks.
		Rift - When an upward moving plume of magma encounters the bottom of a crustal plate, it lifts, or domes the plate.
	my.execpc.com /A2/EA/acmelasr/mountains/definitions.html (887 words)

	Coastal steam plume likely but not constant sight
		Although typically present, the plume is absent whenever the supply of lava to the coast is interrupted.
		The interruption in supply of magma that leads to plume extinction is a fundamental part of the volcano's rift-system tectonics.
		Plume extinction lags a few hours behind the beginning of a pause, because lava already in the tube must drain into the ocean.
	hvo.wr.usgs.gov /volcanowatch/1999/99_07_08.html (750 words)

	Explore Kilauea Volcano \| Geology
		Magma generated by the hot spot rises through the lithospheric plate and produces an active volcano at the Earth's surface.
		For most eruptions, magma migrates to, and is stored in, a shallow reservoir beneath the summit.
		This can be caused by dwindling supply of magma from the hot spot itself, a blockage in the magma conduit or by the magma being diverted to another intrusion or eruption site.
	www.fireworkstudios.com /geology.html (1221 words)

	The PLUME Eperiment
		xperiment studies the shape and the origin of the mantle plume beneath the Hawaiian hotspot that is responsible for spectacular volcanism on the surface.
		Plume basalts (a type of volcanic rock), or OIB (ocean island basalts), seem to be different from mid-ocean ridge basalts (MORB).
		The transition zone between 410 and 660km that separates the upper from the lower mantle tends to be thinner when a hot plume intersects it, where the 660 domes upward and the 410 is depressed.
	mahi.ucsd.edu /Gabi/plume.html (2359 words)

	News in Science - Volcano theories may need revision - 25/08/2003
		The dominant theory is that the interior churns around in a convection current, with upward plumes of hot magma periodically burning through the Earth's crust, in areas known as 'hotspots'.
		Magma plumes creating these hotspots have long been assumed to be fixed, while the overlying tectonic plates of crust - which make up the surface of the Earth - drift slowly, over millions of years, above them.
		This suggested that the magma plume was moving - not stationary.
	www.abc.net.au /science/news/stories/s929822.htm (736 words)

	Mantle plume - Wikipedia, the free encyclopedia
		As the heads of mantle plumes can partly melt when they reach shallow depths, they are thought to be the cause of volcanic centers known as hotspots and probably also to have caused flood basalts.
		It is usually defined as a plume that has a diameter of at least 1500-3000 km by the time the plume head spreads at the base of the lithosphere.
		The apparent linear, age-progressive distribution of the Hawaiian-Emperor seamount chain is explained in this context as a result of a fixed, deep-mantle plume impinging into the upper mantle, partly melting, and causing a "track" as the plate moves with respect to the plume source (Morgan, 1972).
	en.wikipedia.org /wiki/Mantle_plume (1362 words)

	Komatiites
		The MgO contents of magmas is proportional to their melting temperatures (higher MgO means hotter magmas) and the first experiments on komatiites (Green, 1975) were interpreted to imply melting conditions in excess of 1600°C (compared to 1250-1350°C for modern MORB, Figure 2; see also Temperature and Mantle temperature pages).
		In the plume model, the oldest komatiites (Barberton at 3.5 Ga) record the highest mantle potential temperatures, while late Archean (2.7 Ga) Munro komatiites and Cretaceous (8.8 Ma) Gorgona komatiites are formed in progressively cooler plumes.
		Magma temperatures of 50-100°C hotter than the MORB mean are well within the range of expected plate tectonic variations.
	www.mantleplumes.org /Komatiites.html (4217 words)

	Compositional complexity in the (Site not responding. Last check: 2007-10-16)
		Although the origin of that difference is still under debate, it is generally accepted that it is a result of some structural organization of chemical differences in the mantle plume that feeds the Hawaii volcanoes.
		One possibility is that the mantle plume is concentrically zoned (presumably hotter in the middle) and that Loa volcanoes are derived largely from the central part, while Kea volcanoes are derived largely from the peripheral region – although this hypothesis in not universally accepted.
		These inclusions represent magma trapped within the olivine crystals that form early in the cooling of the magma, and, as such, give a picture of the variability of the magma before any homogenization that might take place within a magma chamber beneath a volcano.
	www.mala.bc.ca /~earles/hawaii-plume-aug05.htm (507 words)

	04.12.00 - Moving magma under Mammoth Lakes area may be splitting rocks deep underground, UC Berkeley seismologist ... (Site not responding. Last check: 2007-10-16)
		The magma heats them so suddenly that the expanding water, steam or bubbles drive the rocks apart as much as four inches in a matter of seconds.
		Dreger doubts that magma intrusion is directly involved, because it moves so slowly while the seismic events were triggered in less than a few seconds.
		Dreger suspects the cause is a dike of magma extending upward from the main plume and intersecting a waterlogged fault zone, flash heating and pressurizing the water and forcing the rocks apart.
	www.berkeley.edu /news/media/releases/2000/04/12_mam.html (866 words)

	332
		Mantle Plumes, Hotspots, and the Geodynamics of Continental Rifting and Breakup
		Therefore, even in extensional settings and provided that lithospheric layering is appropriate, mantle plumes may modify the ambient stress field in such a way that formation of concentric contractional structures is favoured in volcanic traps during their emplacement, and at the periphery of the uplift until the excess topography has relaxed.
		This is consistent with the west-to-east progression in the age of the archipelago lavas (Nicolaysen et al., 1996), which correlates with a change from tholeiitic to midly alkaline compositions, an inferred decrease in extent of melting and a presumed increase in the depth of crystallization (Damasceno et al., 1997).
	www.the-conference.com /JConfAbs/4/338.html (17582 words)

	Howstuffworks "How Volcanoes Work"
		In either case, what you get is magma filled with tiny gas bubbles, which have a much lower density than the surrounding magma, and so push out to escape.
		If the magma has a lower viscosity, the gas bubbles will be able to escape from the magma more easily, so the lava won't erupt as violently.
		Generally, viscosity is determined by the proportion of silicon in the magma, because of the metal's reaction to oxygen, an element found in most magmas.
	science.howstuffworks.com /volcano1.htm (1508 words)

	SEMP - The Great Mantle Plume Debate
		Three conspicuous places on Earth are magmatically (derived from magma or lava) very “hot” yet bear NO relation to “plate tectonics” theory, a problem that a klatch of eager scientists addressed in the 1970s with the “mantle plume” theory.
		Mantle plume theory, which developed to address the weaknesses of plate tectonic theory, postulates the existence of hot upwellings called plumes that form somewhere deep in the mantle, perhaps as deep as the core-mantle boundary.
		The basaltic magma rises by buoyancy to the base of continental crust where it forms pools at the base of continental crust.
	www.semp.us /biots/biot_218.html (1162 words)

	PMEL Hydrothermal Plume Studies: Overview
		Hydrothermal plumes are created and sustained by the heat of volcanic processes along the Mid-Ocean Ridge system that circles the globe.
		These plumes are often fl or white with the color coming from mineral particles that precipitate rapidly as hot hydrothermal fluids (with temperatures as high as 340oC) mix with cold seawater (usually about 1-2oC) at or just below the vent orifice.
		Hydrothermal plumes can be detected in seawater overlying vent fields, and beyond, because they have a distinctly different physical and chemical signature from the surrounding seawater.
	www.pmel.noaa.gov /vents/PlumeStudies/plumes-whatis.html (344 words)

	Penn State News
		Kump and James F. Kasting, professor of geosciences and meteorology, together with their Australian colleague Mark Barley, have developed a conceptual model that suggests vulcanism caused a rapid change in oxygen content and the glaciation, but this was a different type of vulcanism than had occurred up until then.
		The rising plumes began to spew carbon dioxide and water, rather than methane and hydrogen, and this allowed the oxygen levels to rise.
		Kump, Kasting and Barley believe that their conceptual model of rapid oxygenation of the atmosphere by deep magma plume volcanos is self consistent and ties together a series of occurrences on different continents.
	www.psu.edu /ur/2000/gsaoxygen.html (538 words)

	Hot Spots and Mantle Plumes--Geosci PS 1030
		Some volcanoes are isolated in the middle of plates and do not seem to be at all related to plate boundaries.
		Mantle plumes form somewhere deep in the mantle, perhaps as deep as the core-mantle boundary
		basaltic magma is derived from the spreading plume through the process of partial melting.
	faculty.weber.edu /bdattilo/shknbk/notes/htsptplm.htm (191 words)

	Unpeeling The Mantle of Io
		D., senior research scientist in earth and planetary sciences, and Bruce Fegley, Jr., Ph.D., professor of earth and planetary sciences, were able to take the Hubble measurements and infer the temperature of the magma and plume pressure of Pele, one of Io's most active volcanoes.
		This is the first time that scientists have used chemical data obtained from a telescope to study present-day interior processes of a solar system body.
		Surprisingly, the magma temperature inferred from the Hubble chemical data corresponds to the temperatures deduced from infrared measurements taken by the Galileo spacecraft orbiting Jupiter.
	www.spacedaily.com /news/galileo-00m.html (599 words)

	Glossary of Terms: M
		Magma that is relative poor in silica but rich in calcium, magnesium, and iron content.
		This type of magma solidifies to form rocks relatively rich in calcium, magnesium, and iron but poor in silica.
		Chain of submarine mountains where oceanic crust is created from rising magma plumes and volcanic activity.
	www.physicalgeography.net /physgeoglos/m.html (2366 words)

	Yellowstone National Park, Part 1
		A hot spot (or mantle plume) is a point where hot, molten magma has risen from the mantle into the crust.
		This plume of magma rises to a depth of around 50 miles and pools beneath Yellowstone.
		Here, large blobs of magma rise from the top of the plume and move up through the mantle and into the crust.
	www.suite101.com /article.cfm/everyday_geology/86400 (524 words)

	BillingsGazette.com :: Study finds plume extends far under park
		The research, recently published in the Journal of Geophysical Research, indicates that the giant plume of magma beneath Yellowstone tilts to the northwest beneath Dillon.
		The plume is not a textbook example that dives more than 1,000 miles into the Earth's core mantle, but appears to be situated more in the upper mantle.
		In recent years, some have theorized that that the traditional idea of a deep plume of molten rock may not be the case beneath Yellowstone.
	www.billingsgazette.net /articles/2006/05/30/news/wyoming/25-plume.txt (860 words)

	Hawaii Forest and Trail - A Hot Spot of Aloha
		Unlike 90% of the earth's volcanoes, which are located at the boundaries of tectonic plates, Hawaii is smack dab in the middle of a plate.
		This fixed plume of magma builds up volcanoes as the Pacific Plate is dragged across it.
		The magma from the hot spot is basic (as opposed to acidic or intermediate) lava.
	www.hawaii-forest.com /essays/9712.html (977 words)

	I would like to know about magma plumes. (Site not responding. Last check: 2007-10-16)
		I was also told that Hawaii is actually a set of sea mounds which were once active volcanoes that moved way from a magma plume and have cooled.
		Mantle plumes are areas where heat and/or rocks in the mantle are rising towards the surface.
		A hot spot is the surface expression of the mantle plume.
	volcano.und.nodak.edu /vwdocs/frequent_questions/grp5/question193.html (309 words)

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