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Members of the peridotite family include:
These peridotite rocks are usually subducted back into the mantle in subduction zones. However, they can be emplaced into or overthrust on continental crust during continental collisions ( orogenies) or island arcAn island arc is a type of archipelago formed by plate tectonics as one oceanic tectonic plate subducts under another and produces magma. It is a type of volcanic arc. Partial melting of both the subducted oceanic lithosphere and the overriding mantle gen collisions by the process of obductionObduction is the overthrusting of continental crust by oceanic crust or mantle rocks. Obduction occurs where a fragment of continental crust is caught in a subduction zone with resulting overthrusting of oceanic mafic and ultramafic rocks from the mantle. The occurances of these peridotites along with other maficMafic is a term used in geology for silicate minerals, magmas, volcanic, and intrusive igneous rocks that have relatively high concentrations of the heavier elements. The term is a combination of " magnesium" and ferric the Latin word for iron(III), but m gabbroGabbro is a dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. It is a plutonic rock, formed when molten magma is trapped beneath the Earth's surface and cools slowly into a hard, coarsely crystalline mass. It is dense, greenishs and basaltBasalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. Basalt in the tops of subaerial lava flows and cinders will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. The term bs within continental crust are referred to as ophiolitesOphiolites are sections of oceanic lithosphere that have been uplifted or emplaced to be exposed within continental crustal rocks. Examples include the Troodos Ophiolite in Cyprus, the Oman Ophiolite in the UAE, and Lizard Point in Cornwall, UK. The strat.
A related rock type, eclogiteEclogite is a coarse-grained, mafic-to-ultramafic grouping of metamorphic rocks of special interest on account of the variety of minerals they contain and their microscopic structures and geological relationships. The fresh rock can be very striking in ap, may be mostly metamorphosed peridotite from deep within the subduction environment.
The rocks of the peridotite family are uncommon at the surface and are highly unstable. Many, if not most, surface outcrops have been highly altered by retrograde metamorphism to serpetinites in which the pyroxenes and olivines have been converted to green serpentine along with amphibole minerals. This hydration reaction involves considerable increase in volume with concurrent deformation of the original textures.