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Shock metamorphism occurs when an extraterrestrial object (a meteorite for instance) collides with the Earth's surface. Impact metamorphism is, therefore, characterized by ultrahigh pressure conditions and low temperature. The resulting minerals (such as SiO 2 polymorphs coesite and stishovite) and textures are characteristic of these ...
The third distinctive feature is from isochemical metamorphism, or the addition or subtraction of major elements other than water (H 2 O) and carbon dioxide (CO 2). [6] The last feature is the distinct zones of metasomatism. These are formed from magmatism and metamorphism and form a characteristic pattern of a metasomatic column. [6]
Soapstone is formed by the metamorphism of ultramafic protoliths (e.g. dunite or serpentinite) and the metasomatism of siliceous dolomites. By mass, "pure" steatite is roughly 63.37% silica, 31.88% magnesia, and 4.74% water. [2] It commonly contains minor quantities of other oxides such as CaO or Al 2 O 3.
The metamorphic rock exposed in orogenic belts may have been metamorphosed simply by being at great depths below the Earth's surface, subjected to high temperatures and the great pressure caused by the immense weight of the rock layers above. This kind of regional metamorphism is known as burial metamorphism.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
A metamorphic reaction is a chemical reaction that takes place during the geological process of metamorphism wherein one assemblage of minerals is transformed into a second assemblage which is stable under the new temperature/pressure conditions resulting in the final stable state of the observed metamorphic rock. [1]
A sample of banded hornfels, formed by contact metamorphism of sandstones and shales by a granite intrusion. Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. [1]
This diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure. The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.