Intrusion (geology) in the context of "Metamorphic rock"

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⭐ Core Definition: Intrusion (geology)

In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; the Henry Mountains of Utah; the Bushveld Igneous Complex of South Africa; Shiprock in New Mexico; the Ardnamurchan intrusion in Scotland; and the Sierra Nevada Batholith of California.

Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained (phaneritic). Intrusive igneous rocks are classified separately from extrusive igneous rocks, generally on the basis of their mineral content. The relative amounts of quartz, alkali feldspar, plagioclase, and feldspathoid is particularly important in classifying intrusive igneous rocks.

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👉 Intrusion (geology) in the context of Metamorphic rock

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. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock.

Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and distortion. Metamorphic rock can be formed locally when rock is heated by the intrusion of hot molten rock called magma from the Earth's interior. The study of metamorphic rocks (now exposed at the Earth's surface following erosion and uplift) provides information about the temperatures and pressures that occur at great depths within the Earth's crust.

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Intrusion (geology) in the context of Liquine-Ofqui Fault

The Liquiñe-Ofqui Fault is major geological fault that runs a length of roughly 1,200 kilometres (750 mi) in a NNE-SSW orientation and exhibits current seismicity. It is located in the Chilean Northern Patagonian Andes. It is a dextral intra-arc strike-slip fault. Most large stratovolcanoes of the Southern Volcanic Zone of the Andes are aligned by the fault which allows for the movement of magma and hydrothermal fluids.

The fault crosses several transverse faults including the Mocha-Villarrica Fault Zone (MVFZ) and the Biobío-Aluminé Fault Zone. The fault has had periods of ductile deformation associated to pluton emplacement, be it either at great depths or by shallow intrusions.

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