amphibolite facies


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Related to amphibolite facies: Blueschist Facies, Granulite Facies, Metabasites

amphibolite facies

[am′fib·ə‚līt ′fā‚shēz]
(petrology)
Rocks produced by medium- to high-grade regional metamorphism.
References in periodicals archive ?
Their protolith corresponds to medium- to coarse-grained pelitic sediments, which were affected by a metamorphism reaching the amphibolite facies. They show a porphyroblastic texture with granoblastic, lepidogranoblastic and poiquiloblastic matrix.
Then, a progressive metamorphism in these rocks is marked by the passing of greenschist facies mineralogy [actinolite + chlorite + quartz + plagioclase (albite) + epidote minerals [+ or -] muscovite [+ or -] calcite] to epidote-amphibolite facies mineralogy [hornblende + epidote minerals + quartz + albite [+ or -] garnet], and finally to amphibolite facies mineralogy [hornblende + garnet + plagioclase [+ or -] quartz].
The graphical analysis of greenschist to amphibolite facies mineral assemblages in metabasites.
The rocks of the Alutaguse zone have metamorphosed under the conditions of the amphibolite facies. In some places (Sonda-Uljaste and Haljala) the rocks show evidence of granulite facies metamorphism.
The rock samples of amphibolite facies show a clear dissimilarity in the acoustopolarigram shape from that of the rocks of prehnite-pumpellyite, greenschist and epidote-amphibolite facies.
These rocks comprise mylonitic peridotite and sub-ophiolitic metamorphic rocks that range from garnetiferous amphibolites facies to amphibolite facies to greenschist facies and un- metamorphosed sediments.
However, in many places retrograde assemblages have formed in the conditions of the amphibolite facies.
This lower amphibolite facies metamorphism overprints, in many samples, a pre-existing epidote-hornfels or greenschist assemblage containing epidote + variably sericitised plagioclase + actinolite [+ or -] biotite.