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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.
The AKF diagram is intended for rocks containing excess aluminium and silica. Its components are: A = Al 2 O 3 - (CaO + Na 2 O + K 2 O) K = K 2 O F = FeO + MgO + MnO. This diagram is less useful, because magnesium does not freely substitute for ferrous iron in many metamorphic minerals important in aluminium-rich rock.
Impactite is rock created or modified by one or more impacts of a meteorite. [1] [2] Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact. [3] On Earth, impactites consist primarily of modified terrestrial material, sometimes with pieces of the original meteorite. [3]
[33] [34] Subsequent erosion of the mountains exposes the roots of the orogenic belt as extensive outcrops of metamorphic rock, [35] characteristic of mountain chains. [33] Metamorphic rock formed in these settings tends to shown well-developed foliation. [33] Foliation develops when a rock is being shortened along one axis during metamorphism.
Original - The rock cycle is a fundamental concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Due to the driving forces of the rock cycle, plate tectonics and the water cycle , rocks do not remain in equilibrium and are forced to change as they ...
In geology, metasedimentary rock is a type of metamorphic rock. Such a rock was first formed through the deposition and solidification of sediment. Then, the rock was buried underneath subsequent rock and was subjected to high pressures and temperatures, causing the rock to recrystallize. The overall composition of a metasedimentary rock can be ...
Pages in category "Metamorphic rocks" The following 59 pages are in this category, out of 59 total. This list may not reflect recent changes. ...
Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock that was reconstituted subsequently by partial melting ("paleosome"), while the alternate layer has a ...