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Topic: Eclogite


In the News (Wed 19 Jun 13)

  
  Eclogite
The depth of trapping depends on the compositions and densities adopted for the eclogite and the adjacent mantle, and the composition of the lower mantle.
Recycling and remelting of large blocks of eclogite is distinct from the thermal plume hypothesis and distinct from the pyroxenite vein hypothesis for increasing fertility.
Eclogite can settle to various levels, depending on composition; the eclogite bodies that can sink to greater depths because of their density have low seismic velocities compared to other rocks with similar density.
www.mantleplumes.org /Eclogite.html   (4896 words)

  
  Blue Ridge Eclogite   (Site not responding. Last check: 2007-10-15)
Eclogite in the hanging wall of the Burnsville fault at Lick Ridge demonstrates that parts of the Eastern Blue Ridge were subducted to depths of at least 40 km.
The eclogites are banded and their preservation of eclogite-facies assemblages is variable, grading from eclogite to garnet-amphibolite to plagioclase-amphibolite over the distance of tens of centimeters.
Eclogite metamorphism in an oceanic subduction zone (foreign model) prior to Taconian collision in the central or northern Appalachians necessitates major Acadian displacement on the Burnsville fault.
geoweb.tamu.edu /Faculty/Miller/BREclogite/BREclogite.html   (2220 words)

  
 ECLOGITE - LoveToKnow Article on ECLOGITE
The hornblende is usually pale green and feebly dichroic, but,in some eclogites which are allied to garnet-amphibolites, it is of dark brown color.
The eclogites in their chemical composition show close affinities to gabbros; they often exhibit relationships in the field which show that they were primarily intrusive rocks of igneous origin, and occasionally contact alteration can be traced in the adjacent schists.
Specimens of rock allied to eclogite have been found in the diamantiferous peridotite breccias of South Africa (the so-called blue ground), and this has givenrise to the theory that these are the parent masses from which the Kimberley diamonds have come.
www.1911encyclopedia.org /E/EC/ECLOGITE.htm   (320 words)

  
 8th INTERNATIONAL KIMBERLITE CONFERENCE (8IKC)
Eclogites of the high-Ca suite may contain diamond or graphite, and garnet and clinopyroxene are similar to one inclusion suite recorded in diamond.
The eclogitic rocks are composed of primary pyrope, omphacite and rutile, with occasional zircon, olivine, orthopyroxene, kyanite, apatite and ilmenite, and secondary garnet, clinopyroxene, amphibole, phlogopite, epidote, chlorite and serpentine.
Eclogite xenoliths in kimberlites and alkali basalts are of great scientific interest because they provide information on the chemistry, mineralogy, and petrology of the mantle, as well as on the evolutionary history and interaction between the mantle and the crust.
www.venuewest.com /8IKC/s2post.htm   (5633 words)

  
 COMPARISON OF METAMORPHIC HISTORY AND DEFORMATION ACROSS WELL-EXPOSED CONTACTS BETWEEN ECLOGITE PODS AND ...   (Site not responding. Last check: 2007-10-15)
Eclogites are comprised of garnet + omphacite + rutile + quartz + white mica ± epidote.
In pristine eclogite pods, garnets are < 1 mm in diameter, inclusion-free, and characterized by an increase in Mg from core to outer core, and a dramatic decrease in Mg at the rim.
Zoning trends in blueschist and eclogite garnets are similar: Mg increases from core to outer core, with an abrupt decrease at the rim.
gsa.confex.com /gsa/2002AM/finalprogram/abstract_44271.htm   (486 words)

  
 Eclogite   (Site not responding. Last check: 2007-10-15)
The pale green pyroxene and red garnet are diagnostic of this rock.
This striking red and pale green colors of eclogites main minerals are well expressed here.
Eclogite is associated with the high pressure/high temperature processes found in the mantle.
csmres.jmu.edu /geollab/Fichter/MetaRx/Rocks/Eclogite1.html   (54 words)

  
 Olympus Microscopy Resource Center: Polarized Light Microscopy Gallery - Eclogite
Eclogites are a small group of rocks that are predominantly composed of green pyroxene interspersed with red garnets.
Scientists have been studying eclogite for many years, and some have come to the conclusion that the rock is likely characteristic of large areas of the Earth’s upper mantle.
Evidence for this view has been drawn from a variety of sources, including examination of eclogite intrusions, as well as laboratory simulations of the conditions that would be involved in the creation of such sizeable masses of eclogite within the planet.
www.olympusmicro.com /galleries/polarizedlight/pages/eclogitesmall.html   (237 words)

  
 THE TECTONIC IMPLICATIONS OF 460 MA ECLOGITE ALONG THE TACONIAN SUTURE IN THE EASTERN BLUE RIDGE OF NORTH CAROLINA   (Site not responding. Last check: 2007-10-15)
460 Ma eclogite near the base of the Ashe Metamorphic Suite (AMS) at the contact between the eastern and western Blue Ridge in North Carolina supports the idea that the AMS is part of an accretionary complex that was sutured to the Laurentian margin during the Taconian orogeny.
This could indicate that eclogite metamorphism in the Blue Ridge was associated with the Taconian collision and would imply that large segments of the margin were buried to eclogite facies depths during the collision.
One solution to this problem is that the eclogite was generated in a subduction zone farther north, in the central or northern Appalachians where the Taconian collision occurred much later than in the southern Appalachians.
gsa.confex.com /gsa/2001SE/finalprogram/abstract_4759.htm   (508 words)

  
 Convergent metamorphism of eclogite and garnet-bearing ultramafic rocks at Lien, West Norway
Eclogite and garnet peridotite and pyroxenite are important features in the supracrustal sequence of the Basal Gneiss region in West Norway.
Three modes of origin have been proposed for these rock types: (1) both eclogite and garnet-bearing ultramafic rocks equilibrated in the upper mantle and subsequently were tectonically emplaced in their present positions
The Lien peridotite seems to have been derived from the upper mantle in eclogite facies conditions and emplaced into unusually thick continental crust during an eclogite facies metamorphic event.
www.nature.com /cgi-taf/DynaPage.taf?file=/nature/journal/v283/n5746/abs/283470a0.html   (267 words)

  
 Olympus Microscopy Resource Center: Polarized Light Microscopy Gallery - Eclogite
Eclogite is formed when igneous or metamorphic rocks that contain significant amounts of mafic minerals are exposed to pressures that exceed 1.5 gigapascals and high temperatures.
Though chemically similar to basalt, the appearance of eclogite is quite distinct, being significantly more colorful than many other types of rocks.
Typically present on Earth in small blocks or bodies, some of the best-known occurrences of eclogite are found in California, Norway, South Africa, Scotland, and the Alps.
www.olympusmicro.com /galleries/polarizedlight/pages/eclogitelarge.html   (109 words)

  
 [No title]   (Site not responding. Last check: 2007-10-15)
Garnet and clinopyroxene are the two major minerals in eclogite.
Eclogite is basalt which has been metamorphosed at very high pressures in subduction zones.
Want to see what an eclogite looks like after a little retrograde metamorphism?
www.geolab.unc.edu /Petunia/IgMetAtlas/meta-micro/eclogite1.X.html   (37 words)

  
 Stef's Wonderful World of Geology
The exhumation mechanism for large eclogite blocks in the Blue Ridge is an ongoing debate in Appalachian geology.
Current hypotheses suggest that eclogite facies rocks are typically exhumed by one of three mechanisms; as high-grade blocks entrained in flowing mélange (e.g.
Recent research shows uniform omphacite c-axis orientations among widely scattered blocks of eclogite in the Blue Ridge, implying that they were exhumed within a coherent, regional eclogite facies terrane (Syvertsen, 2004).
www.unc.edu /~sdilts/research.html   (410 words)

  
 P-T-D Path of Eclogite from the Sambagawa Belt Deduced from Combination of Petrological and Microstructural Analyses -- ...
P-T-D Path of Eclogite from the Sambagawa Belt Deduced from Combination of Petrological and Microstructural Analyses -- AOYA 42 (7): 1225 -- Journal of Petrology
between the eclogitic schist and surrounding non-eclogitic schist.
deformation is related to exhumation of the eclogitic schist
petrology.oxfordjournals.org /cgi/content/abstract/42/7/1225   (403 words)

  
 Characteristics activities of subcrustal earthquakes along the outer zone of Southwestern Japan
The subducting crust is predicted to undergo a series of dehydration reactions with increasing temperature and depth, culminating in the formation of nearly anhydrous eclogite at 80—90 km depth.
Hydrous minerals are predicted to be stable in the crust to depths of ~105 km at the transition to eclogite, with the bulk of the dehydration occurring within the lawsonite amphibole eclogite stability field.
Earthquakes in the lower zone occur chiefly within the portion of the subducting mantle that we predict is a serpentine- or chlorite-bearing harzburgite.
zephyr.rice.edu /sota/papers/Hacker,BradHacker_abstract.doc   (1850 words)

  
 Search Results for eclogite - Encyclopædia Britannica
Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with...
The eclogite facies was initially recognized in rocks only of basalticcomposition, which are transformed at the pressure-temperature conditions of the eclogite facies into spectacular red and green...
Expand your search on eclogite with these databases:
www.britannica.com /search?query=eclogite&submit=Find&source=MWTEXT   (308 words)

Try your search on: Qwika (all wikis)

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