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	Ophiolites
		Ophiolites are pieces of oceanic plate that have been thrusted (obducted) onto the edge of continental plates.
		Ophiolites are an assemblage of mafic and ultramafic lavas and hypabyssal rocks found in association with sedimentary rocks like greywackes and cherts.
		Ophiolites are characterized by a classic sequence of rocks.
	volcano.und.nodak.edu /vwdocs/vw_hyperexchange/ophiolites.html (421 words)

	[No title]
		Ophiolite is interpreted to be thrust sheet of ancient oceanic lithosphere which has been obducted over the continental crust in the course of orogeny.
		Ophiolite was first described from the Alps in the early 20th century, and was later discovered from almost every orogenic belt on the earth.
		Ophiolite occurs as a nappe (intact thrust sheet) or as a melange (tectonic mixture of fragments).
	earth.s.kanazawa-u.ac.jp /ishiwata/ophiol_e.htm (943 words)

	Geological Society of America - Ophiolites and Oceanic Crust - Press Release
		Ophiolites (from the Greek words "ophis" --snake, and "lithos"--rock) are fragments of the oceanic crust and mantle that are found preserved in the Earth's mountain belts.
		The discovery of copper in ophiolitic volcanic rocks in the Mediterranean region ushered in the Bronze age in the history of human civilizations.
		The second Penrose Conference on ophiolites in 1998 brought together 86 experts in structural geology, tectonics, geophysics, petrology, and geochemistry to explore new advances and discoveries concerning ophiolites and related drilling from the oceanic crust.
	www.geosociety.org /news/pr/01-43.htm (537 words)

	Ocean Crust Geochemistry - Oman Ophiolite
		Plagiogranites (white hills in the distance) intrude the base of the mafic (dark) metavolcanics seen in the foreground in the Lasail mine in Oman. The small arch in the center of the foreground is the original opening to the ancient mine dug by hand by Phoenician slaves.
		Ophiolites also provide exposures of ancient hydrothermal systems where alteration channels can be traced from the reaction zone to the discharge site at an ore deposit.
		Magma chamber cross-section and the layer-cake stratigraphy of the oceanic crust:
	www.mbari.org /crust/Oman.htm (371 words)

	precambrian ophiolites (Site not responding. Last check: )
		Ophiolites are very sensitive indicators of thermal, compositional, structural, and melting conditions in the Earth, and therefore comparative studies of Precambrian and younger ophiolites can yield information about how the Earth has evolved with time.
		Ophiolites are a distinctive association of rocks interpreted to form in a variety of plate tectonic settings, including oceanic spreading centers, back-arc basins, forearcs, arcs, and other extensional magmatic settings including those in association with plumes.
		The harzburgite is generally interpreted to be the depleted mantle from which overlying mafic rocks were derived, and the deformation is related to the overlying lithospheric sequence flowing away from the ridge along a shear zone within the harzburgite.
	www.eas.slu.edu /People/TMKusky/precamb_ophiolites.html (3380 words)

	Ophiolites Summary
		Ophiolites may be overprinted by greenschist facies metamorphic assemblages and exhumed during collapse of a thrust-thickened orogen.
		Ophiolites are sections of the oceanic crust and the subjacent upper mantle that have been uplifted or emplaced to be exposed within continental crustal rocks.
		The subduction-related chemistry of ophiolites and their association with mountain belts suggests that their formation and emplacement are related to oceanic closure and continental collision (final stages of the Wilson Cycle) rather than oceanic opening and seafloor spreading as was first thought.
	www.bookrags.com /Ophiolites (1058 words)

	Ophiolites Encyclopedia Information @ Karr.net (Karr Network) (Site not responding. Last check: )
		Ophiolites are sections of the oceanic crust and the subjacent upper mantle that have been uplifted or emplaced to be exposed within continental crustal rocks.
		Ophiolites with compositions comparable with hotspot-type eruptive settings or normal mid-oceanic ridge basalt are rare, and those examples are generally strongly dismembered in subduction zone accretionary complexes.
		The subduction-related chemistry of ophiolites and their association with mountain belts suggests that their formation and emplacement are related to oceanic closure and continental collision (final stages of the Wilson Cycle) rather than oceanic opening and seafloor spreading as was first thought.
	www.alienartifacts.com /encyclopedia/Ophiolites (1769 words)

	Ophiolites (Site not responding. Last check: )
		The stratigraphic sequence observed in ophiolites corresponds to the lithosphere-forming processes at mid-oceanic ridges: :Sediments: Muds (fl shale) and cherts deposited since the crust formed.
		One of the big problems relating oceanic crust and ophiolites is the thick gabbro layer of ophiolites calls for large magma chambers beneath mid-ocean ridges.
		The crystallization order of feldspar and pyroxene in the gabbros is unexpectedly reversed, and ophiolites also appear to have a multi-phase magmatic complexity on par with subduction zones.
	ophiolites.area51.ipupdater.com (445 words)

	The Geology of Cyprus \| GeologyRocks
		Examples of this are seen in the well-preserved ophiolites of Cyprus (Troodos), southern Turkey (Kizildag), and the Baer-Bassit ophiolite of Syria (Dilek and Moores, 1990).
		Multistage alteration in the extrusive sequence of the Troodos Ophiolite, Cyprus.
		Robertson, A. Overview of the genesis and emplacement of Mesozoic ophiolites in the Eastern Mediterranean Tethyan region.
	www.geologyrocks.co.uk /tut.php?id=22 (4584 words)

	Ophiolites. - Geology - What's Been Published (Site not responding. Last check: )
		Ophiolites and oceanic lithosphere / edited by I.G. Gass, S.J. Lippard & A.W. Shelton.
		Structures of ophiolites and dynamics of oceanic lithosphere / by A. Nicolas.
		Ophiolites and oceanic crust : new insights from field studies and the ocean drilling program / edited by Yildirim Dilek...
	www.pitbossannie.com /rps-qe-ophiolites.html (82 words)

	Josephine Ophiolite
		We've agreed that ophiolites are chunks of the seafloor.
		Ophiolites are one of the few environments where the tectonic setting is sufficiently rude to cause this to happen, and believe me when I say that the ultramafics aren't happy up here at all.
		There will be several more exposures of ophiolitic rocks at the beginning, but much of what we will see as we head west was part of a chain of volcanic islands which were the result of subduction of the crust immediately west of the behind-the-arc spreading ridge which formed the ophiolite.
	jersey.uoregon.edu /~mstrick/GeoTours/Josephine%20Ophiolite/JoOphiolite.html (19694 words)

	Anais da Academia Brasileira de Ciências - Mid amphibolite facies metamorphism of harzburgites in the Neoproterozoic ... (Site not responding. Last check: )
		All known ophiolites of this age were identified on the basis of the nature of the associated juvenile continental crust, because no direct evidence of mantle deformation has been preserved in the contained minerals.
		Similarly to northeast Africa, the Brazilian ophiolites occur in the juvenile terranes identified in the Neoproterozoic Brasiliano Cycle orogenic belts, the Goiás magmatic arc in Central Brazil (Pimentel and Fuck 1992) and the Vila Nova belt (Figs.
		mineralogical assemblage of the harzburgite in the ophiolite is characteristic of metamorphic harzburgites recrystallized in the mid amphibolite facies (Evans and Trommsdorf 1974, Evans 1977, Bucher and Frey 2002).
	www.scielo.br /scielo.php?script=sci_arttext&pid=S0001-37652003000100012&lng=en&nrm=iso&tlng=en (4651 words)

	Definition of Ophiolites
		Ophiolites are sections of oceanic lithosphere that have been uplifted or emplaced to be exposed within continental crustal rocks.
		The stratigraphic sequence observed in ophiolites corresponds to the lithosphere-forming processes at mid-oceanic ridges:
		Compositional differences regarding silica content for example place ophiolite basalts in the domain of subduction zones (~55% silica) (whereas mid-ocean ridge basalts typically have a value ~50%).
	www.wordiq.com /definition/Ophiolites (300 words)

	Did Tectonics Get an Early Start? :: Astrobiology Magazine ::
		Ophiolites are rock structures that form at oceanic spreading ridges.
		Kusky and his team are in the process of submitting several proposals to the U.S. National Science Foundation to characterize and study the petrological, chemical, and structural aspects of the Dongwanzi ophiolite.
		He is also submitting proposals to NASA to investigate and interpret the signs of life in the rocks, and to determine the implications for the evolution of early life on earth.
	www.astrobio.net /news/modules.php?op=modload&name=News&file=article&sid=168 (1198 words)

	Geotimes - June 2001: News Notes
		The discovery of this complete ophiolite complex dating back to the Archean, 2.5 billion years ago, is a major coup for geophysicists.
		Since it takes the spreading of the oceanic crust to give birth to the assemblage of rocks that define an ophiolite, these rocks are an intrinsic part of the story of plate tectonics.
		This was based on a 1987 identification of a 1.960 billion-year-old ophiolite in Finland and by a 1992 report of a Canadian ophiolite that was 1.998 billion years old.
	www.geotimes.org /july01/oldest_ophiolite.html (674 words)

	WHOI : Oceanus : Unraveling the Tapestry of Ocean Crust
		The great extent of these ophiolites, once deep beneath the seafloor but now exposed, provides a comprehensive view of the internal geometry of oceanic plates that is unmatched by any sampling or imaging technique at sea.
		A striking feature of well-exposed ophiolites is a continuous layer of “sheeted dikes,”; which lies between the lava and the gabbro.
		It is difficult to use ophiolites to explore a themodynamic theory of drainage morphology for mantle melt transport mechanisms—because ophiolites constitute a “frozen” system.
	www.whoi.edu /oceanus/viewArticle.do?id=2502 (2316 words)

	IngentaConnect Rift-Drift, Seafloor Spreading, and Subduction Tectonics of Alban...
		Albanian ophiolites in the Dinaride-Albanide-Hellenide mountain system in the Balkan Peninsula represent oceanic remnants of the Mesozoic Pindos-Mirdita basin and structurally overlie the peripheral tectonic units, composed mainly of volcanosedimentary rift assemblages and conjugate passive margin sequences.
		The subophiolitic mélange contains blocks and clasts of material derived from ophiolites, metamorphic units, platform carbonates, and passive margin sequences, and represents a subductionaccretion complex formed during initial displacement and tectonic emplacement of the ophiolites.
		Ophiolites in the Mirdita region show a transition from MORB to IAT and boninitic affinities from west to east and structurally upwards, indicating magma genesis from highly depleted, refractory mantle sources increasingly affected by subduction-derived fluids.
	www.ingentaconnect.com /content/bell/igr/2005/00000047/00000002/art00002 (465 words)

	Emplacement of Cuban Ophiolites (Site not responding. Last check: )
		The basement metamorphic rocks of the Volcanic Arc Terrane were derived from Upper Jurassic- Neocomian oceanic crust, metamorphosed during the development on this crust of a Middle Cretaceous volcanic arc.
		Ophiolites of the northern belt were probably derived from both the formerly mentioned small oceanic basin and suprasubduction marginal basin, and were emplaced in several episodes from the Campanian to the Middle Eocene.
		The different ophiolite types in Cuba represent relics of the oceanic lithosphere (the Proto-Caribbean oceanic basin) that developed between North and South America after the Pangea breakup.
	www.geologica-acta.com:8080 /geoacta/MostrarAbstractAC.do?abstract=gav0303a05 (128 words)

	Avalon Development Corporation - Fairbanks Alaska - Mineral Exploration Experts
		Ophiolitic complexes originate at ocean ridge spreading centers and are commonly composed of a basal unit consisting of differentiated ultramafic and mafic rocks overlain by sheeted mafic dikes which are in turn overlain by submarine basaltic lava flows often associated with deep-water marine cherts.
		Ophiolites are typically more complex structurally than other PGE-permissive settings due to transport on the host oceanic plate and their subsequent obduction at convergent plate margins.
		Ophiolites commonly contain anomalous chromium, copper and nickel but the distribution of PGEs in Alaskan ophiolites is poorly documented.
	www.avalonalaska.com /pge.htm (1626 words)

	Denison Geology & Geography Dept. - Journal of GeoSciences
		Ophiolites represent fragmented slabs of oceanic crust that have escaped recycling by subduction.
		Ophiolite emplacement is believed to occur by obduction, which consists of a fragment of oceanic crust being thrust over continental material instead of being subducted.
		Ophiolites were first discovered in the geologic rock record at 2.0 Ga and reasons concerning the lack of older ophiolites are disputed.
	www.denison.edu /geology/geojournal/lydy00.html (355 words)

	Ophiolites (Site not responding. Last check: )
		Ophiolites are pieces of oceanic plate that have been thrusted (obducted) onto the edge of continental plates.
		Ophiolites are an assemblage of mafic and ultramafic lavas and hypabyssal rocks found in association with sedimentary rocks like greywackes and cherts.
		The base of the sequence is sedimentary rocks of the Arabian shield, not part of the ophiolite, on which the oceanic plate was pushed.
	volcano.und.edu /vwdocs/vw_hyperexchange/ophiolites.html (421 words)

	TEXT
		Ophiolites are fragments of ancient oceans later trapped in continental crusts.
		Most ophiolites represent suture zones between collided continental blocks or between collided arcs and continents.
		The more exotic models create ophiolites in back arc basins, mostly associated with exotic arcs that approach western NAM from far to the west.
	jan.ucc.nau.edu /~rcb7/Text_WUS.html (2470 words)

	January media highlights-GSA Bulletin
		Ophiolites (from the Greek words ophis--snake, and lithos--rock) are fragments of oceanic crust and mantle formed at spreading centers and preserved on land.
		Because no oceanic crust in the oceans is older than about 200 million years, ophiolites also provide us with the only information preserved for oceanic spreading processes prior to 200 million years ago, that is, for the first 96% of Earth history.
		The chemical composition and structure of these very old ophiolites suggest that the nature of the oceanic crust was quite different prior to 1 Ga than at present.
	www.eurekalert.org /pub_releases/2002-01/gsoa-jmh010802.php (1406 words)

	THE SEMAIL OPHIOLITE/OMAN
		The Oman ophiolite is a remnant of the Tethysian oceanic lithosphere obducted on the Arabian continental margin during the Maastrichtian (around 70 Ma).
		The Masirha Ophiolite was upthrust in the Early Cretaceous during the northward movement of the Gondwanaland away from the Oman coast.
		The base of the Semail Ophiolite is marked by a major thrust zone that separates the ophiolite and its basal metamorphic sheet from the underlying rocks.
	www.angelfire.com /ms/snasir/page14.html (1257 words)

	Greg Harper
		Fe-Ti basalts in the Josephine ophiolite and propagating ridge tectonics, Klamath Mountains, California-Oregon.
		Oceanic versus emplacement-age serpentinization in the Josephine Ophiolite: implications for the nature of the Moho at intermediate and slow-spreading ridges.
		Formation and Emplacement of the Josephine ophiolite and the age of the Nevadan orogeny in the Klamath Mountains, California-Oregon: U/Pb zircon and 40Ar/39Ar geochronology: J.
	www.albany.edu /geosciences/gharper.html (399 words)

	Ocean Drilling Program: GSA Special Publication News Release
		The discovery of copper in ophiolitic volcanic rocks in the Mediterranean region ushered in the Bronze Age in the history of human civilizations.
		The second Penrose Conference on ophiolites in 1998 brought together 86 experts in structural geology, tectonics, geophysics, petrology, and geochemistry to explore new advances and discoveries concerning ophiolites and related drilling from the oceanic crust.
		Hydrothermal alteration and fluid fluxes in ophiolites and oceanic crust
	www-odp.tamu.edu /public/pressrel_html/gsa_ophiol.html (1003 words)

	Ocean Basins
		An ophiolite is a sequence of rocks that appears to represent a section through oceanic crust.
		Ophiolites occur in areas where obduction (the opposite of subduction) has pushed a section of oceanic lithosphere onto continental crust.
		An idealized ophiolite sequence shows an upper layer consisting of deep sea sediments (limestones, cherts, and shales), overlying a layer of pillow basalts.
	www.tulane.edu /~sanelson/geol212/ocean_basins.htm (6207 words)

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