Eclogite


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Related to Eclogite: Blueschist, granulite, Greenschist

eclogite

[′ek·lə‚jīt]
(petrology)
A class of metamorphic rocks distinguished by their composition, consisting essentially of omphacite and pyrope with small amounts of diopside, enstatite, olivine, kyanite, rutile, and rarely, diamond.

Eclogite

 

a metamorphic rock, composed chiefly of clinopy-roxene and garnet. The clinopyroxene (omphacite) is a mixture of diopside, hedenbergite, and jadeite components; the mixed-composition garnet contains pyrope and almandine, as well as variable amounts of grossularite and andradite. Eclogite varieties with significant amounts of grossularite and disthene (kyanite) are called grospydites.

Various types of eclogite are distinguished according to the content of secondary minerals, including amphibole, enstatite, olivine, plagioclase, kyanite (disthene), corundum, rutile, graphite, and diamond-containing eclogites. Three types are distinguished on the basis of geological conditions of occurrence: the eclogites of the metamorphic zone, which are associated with glaucophane schists and alpine-type hyperbasites; the eclogites of granulite, gneiss, and amphibolite metamorphic complexes; and eclogites that form inclusions (xenoliths) in kimberlites and alkali basaltoids. The first two are formed within the crust; the last is of mantle origin. Deposits of rutile are associated with eclogite, and diamonds are found among the most deep-seated eclogites in kimberlite pipes.

A. A. MARAKUSHEV

References in periodicals archive ?
The Alpine networks of eclogite polished blades are by no means out of step with a general cultural evolution.
The chemistry of the mineral inclusions can be compared with those present in the eclogite and peridotite fragments in order to determine their source.
The sequence of under thrusting and collision led to the capture of eclogite in the sub continental mantle keel along with the fluids that are needed to make diamonds," added Shirey.
Blocks of serpentinite, gabbro, and blue schist are observed throughout the unit, and eclogite blocks are suspected to be present.
The Project is underlain by rocks of the Yukon-Tanana Terrane consisting of Paleozoic metavolcanic and metasedimentary rocks of the Cleary Sequence and Fairbanks Schist, which are in thrust contact and interleaved with eclogite and amphibolite facies rocks of the Chatanika Terrane.
In addition, the flat HREE patterns are also a strong argument that the magmas are not directly derived from melting of the subducted slab, because oceanic lithosphere subducted to 110 km depth would be metamorphosed to eclogite (a garnetomphacite bearing metamorphic rock).
Significant quantities of garnet must be left in the residue to produce andesitic melts by partial melting of basaltic eclogite (2).
Anderson at the California Institute of Technology in Pasadena contends the transition zone holds both olivine and a high concentration of eclogite -- a rock made of garnet and clinopyroxene.
Group I eclogite garnets, which can be associated with high diamond
The researchers turned to eclogite, a metamorphic rock that forms from ocean floor basalt in the subduction channel.
Comment on "Redistribution of trace elements during prograde metamorphism from lawsonite blueschist to eclogite facies; implications for deep subduction-zone processes" by C.
98 carats from 192 kilos of eclogite during preliminary auger drilling on its Victory Strike Project.