What does intrusive igneous mean?

Asked by: Kirk Wallace

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.

What is the meaning of intrusive igneous rock?

Intrusive, or plutonic, igneous rock forms when magma is trapped deep inside the Earth. Great globs of molten rock rise toward the surface.

What is intrusive and extrusive mean?

The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

What is the meaning of extrusive igneous rock?

Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff.

What is called intrusive?

Definition of intrusive



1a : characterized by intrusion. b : intruding where one is not welcome or invited. 2a : projecting inward an intrusive arm of the sea. b(1) of a rock : having been forced while in a plastic state into cavities or between layers.

Which rocks are intrusive?

intrusive rock, also called plutonic rock, igneous rock formed from magma forced into older rocks at depths within the Earth’s crust, which then slowly solidifies below the Earth’s surface, though it may later be exposed by erosion.

Is an example of intrusive igneous rock?

Diorite, granite, and pegmatite are examples of intrusive igneous rocks.

How do you tell if a rock is intrusive or extrusive?

Crystal Size and Texture



The most obvious difference between extrusive rocks and intrusive rocks is crystal size. Because extrusive rocks cool quickly, they only have time to form very small crystals such as basalt or none at all. On the other hand, intrusive rocks grow larger crystals because they take longer to cool.

What are the 3 characteristics of intrusive igneous rocks?

Characteristics of Intrusive Rocks

• Formation. Intrusive rocks are formed from magma deep in the earth. …
• Texture. Rock textures refer to crystal characteristics visible with the unaided eye. …
• Color. Igneous rocks are categorized by light, medium and dark colors. …
• Intrusive Rock Formations.

What are characteristics of intrusive igneous rocks?

Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The cooling of magma deep in the Earth is typically much slower than the cooling process at the surface, so larger crystals can grow.

What are the three types of igneous rocks?

The most common types of igneous rocks are: andesite. basalt. dacite.

What are 2 types of igneous rocks?

This results in two groups: (1) plutonic intrusive igneous rocks that solidified deep within the crust and (2) volcanic, or extrusive, igneous rocks formed at Earth’s surface.

Is granite intrusive or extrusive?

intrusive igneous rock

granite, coarse- or medium-grained intrusive igneous rock that is rich in quartz and feldspar; it is the most common plutonic rock of the Earth’s crust, forming by the cooling of magma (silicate melt) at depth.

Are intrusive rocks fine grained?

If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture.

What is the most common intrusive igneous rock?

Granite

Granite is the most common intrusive rock on the continents; gabbro is the most common intrusive rock in oceanic crust.

What are the 5 intrusive igneous rock structures?

Intrusive Structures

• Dikes. A dike is an intrusive rock that generally occupies a discordant, or cross‐cutting, crack or fracture that crosses the trend of layering in the country rock. …
• Sills. …
• Laccoliths. …
• Volcanic necks. …
• Plutons.

What are the examples of extrusive igneous rock?

Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals. Some cool so quickly that they form an amorphous glass. These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff.

What are the 5 intrusive igneous rock structures?

Intrusive Structures

• Dikes. A dike is an intrusive rock that generally occupies a discordant, or cross‐cutting, crack or fracture that crosses the trend of layering in the country rock. …
• Sills. …
• Laccoliths. …
• Volcanic necks. …
• Plutons.

What are the four 4 main types of igneous intrusions?

As has already been described, igneous rocks are classified into four categories, based on either their chemistry or their mineral composition: felsic, intermediate, mafic, and ultramafic.

What are the characteristics of intrusive igneous rocks?

Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. The cooling of magma deep in the Earth is typically much slower than the cooling process at the surface, so larger crystals can grow.

What is the most common intrusive igneous rock?

Granite

Granite is the most common intrusive rock on the continents; gabbro is the most common intrusive rock in oceanic crust.

Where do intrusive rocks form?

Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form intrusions, such as batholiths, dikes, sills, laccoliths, and volcanic necks.