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In geology and materials science, a deformation mechanism is a process occurring at a microscopic scale that is responsible for deformation: changes in a material's internal structure, shape and volume. [1] [2] The process involves planar discontinuity and/or displacement of atoms from their original position within a crystal lattice structure.
Neomorphism is considered aggrading when recrystallization results in an any increase in crystal size. The crystal mosaics of the original mineral or crystal formation(s) often experience deterioration in the process and are eventually replaced with either crude crystalline mosaics or polymorphs. Both the resultant crystalline mosaics and/or ...
During this process, the physical structure of the minerals is altered while the composition remains unchanged. [1] [2] This is in contrast to metasomatism, which is the chemical alteration of a rock by hydrothermal and other fluids. Solid-state recrystallization can be illustrated by observing how snow recrystallizes to ice.
The change in the grain size and orientation in the rock during the process of metamorphism is called recrystallization. For instance, the small calcite crystals in the sedimentary rocks limestone and chalk change into larger crystals in the metamorphic rock marble . [ 13 ]
Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous rock or another older metamorphic rock—to different temperature and pressure conditions than those in which the original rock was formed. This process is called metamorphism, meaning to "change in form". The result is a profound change in physical properties ...
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith ) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, elevated pressure of 100 megapascals (1,000 bar ) or more, causing profound physical or chemical changes.
Holmquist 1916 called the process whereby metamorphic rocks are transformed into granulite ‘anatexis’. [ 8 ] The segregation of melt during the prograde part of the metamorphic history (temperature > solidus) involves separating the melt fraction from the residuum, which higher specific gravity causes to accumulate at a lower level.
Layers of rock that fold into a hinge need to accommodate large deformations in the hinge zone. This results in voids between the layers. These voids, and especially the fact that the water pressure is lower in the voids than outside of them, act as triggers for the deposition of minerals.