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Director Tyson Brown, National Geographic Society Author National Geographic Society Production Managers Gina Borgia, National Geographic Society Jeanna Sullivan, National Geographic Society Program Specialists Sarah Appleton, National Geographic Society, National Geographic Society Margot Willis, National Geographic Society otherLast Updated July 15, 2022 Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies. Intrusive Igneous Rocks: Extrusive Igneous Rocks: Download PDF More About Intrusive Igneous Rocks
Intrusive Igneous rocks are those rocks that are formed from the magma beneath the surface of the Earth. Igneous rocks are those types of rocks, which are formed with the cooling of molten rock to a solid state. These rocks are formed from magma and thus these are the rocks that begin the rock cycle, they are also known as primary rocks. These can be easily identified with their features such as texture, colour, density and mineral composition. These are generally further divided into two types: Intrusive or Extrusive. Here, in this article, we will learn about the intrusive volcano, intrusive forms, Intrusive rocks, its diagram, features, types, etc. IntroductionA volcano is an opening on the surface of a planet that leads to the escape of various warmer materials such as lava, gases, dust, ashes, etc. from its interior. This escape occurs because of the eruption of the volcano and this eruption can be explosive or on the other hand, it can be calmer which includes a gentle flow of the lava out of the volcano. Basically, these can be of two types i.e. Intrusive or Extrusive. Intrusive VolcanoIntrusive volcanism is a type of activity where magma is forced into the rocks that make up the crust of the Earth and when with time it cools and later becomes solid but still remains underground, this leads to the formation of different features such as plutons. Due to intrusive volcano activity, intrusive igneous rock formation occurs here. Intrusive FormsDuring volcanic eruptions, the lava which is discharged out of it leads to the formation of igneous rocks after cooling down. This cooling of the lava may take place in two ways; either after arriving on the surface or while the lava is still in the crustal portion. Igneous rocks are generally classified into two types i.e. plutonic rocks as well as volcanic rocks depending upon the location of the cooling of the lava. The lava which cools inside the portions of the crust of the Earth takes various diverse forms and these forms are known as intrusive forms. Intrusive Igneous RocksIntrusive igneous rocks are types of rocks that cool underground and deep in the crust below the surface magma cools slowly and this slow cooling gives crystals enough time and a chance to grow. Therefore, these types of rocks have relatively large crystals which are easy to see. These are also known as plutonic rocks where pluton means an igneous rock body that forms within the crust. Intrusive Igneous FeaturesThe various features of these type of rocks are mentioned below:
Intrusive Igneous Rocks Diagram[Image will be Uploaded Soon] Here, in the aforementioned diagram, we can clearly see how Intrusive rocks are formed beneath the surface of the Earth due to the trapping of magma inside the Earth's surface and their magma cools and solidifies with time and leads to the formation of various types of rocks. Long and slow timing of cooling leads to the formation of the coarse-grained texture of these rocks. Types of Intrusive Igneous RocksThe Intrusions which actually intrude the rocks at shallow levels of the crust are known as hypabyssal intrusions. Here, shallow refers to the depths of generally less than about 1 km. These kinds of intrusions always show sharp contact relations with the rocks they intrude. Several types are mentioned below:
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[Image will be Uploaded Soon] Besides these, if we talk about plutons, these are generally much larger intrusive bodies that have intruded much deeper. They may show sharp contacts with the surrounding rocks but on the other hand at deeper levels, the contacts are often gradational. Several types are mentioned below:
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Fun FactIntrusive rocks formed below the surface but due to geological processes, some intrusive igneous rocks have been brought to the surface. For example The following landscape in the Sierra Nevada Mountains of California which are made up of granite that has been raised to create mountains. [Image will be Uploaded Soon] ConclusionThus, in this article, we have covered the Intrusive rocks which are an important type of Igneous rocks that are formed from the magma, especially the magma which cools into a solid form under the surface of the Earth. The volcanic eruptions of the intrusive volcano lead to the formation of such rocks and various other forms such as dikes, sills, laccoliths, etc. These occur below the surface but sometimes due to the geological processes, these can be exposed on the surface as well. This topic will be helpful to increase your understanding of igneous rocks in Geology, Geography, Earth Sciences, Physical Geography, Geomorphology, etc. Recently Updated Pages Temperature Inversion - Types, Conditions, Effects and FAQs Jet Stream - Layers, Formation, Types, Facts and FAQs Forest Fire - Types, Effects, Natural Disaster and Management Fly Ash - Concrete, Bricks, Sources, Relation and Facts Rivers - Origin, History, Formation and Uses Typhoon - Formation, Structure, Differences and FAQs What are the intrusive igneous rocks?Intrusive Igneous Rock
Intrusive, or plutonic, igneous rock forms when magma remains inside the Earth's crust where it cools and solidifies in chambers within pre-existing rock. The magma cools very slowly over many thousands or millions of years until is solidifies.
What are the 4 main types of igneous rocks?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 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 3 types of intrusive rock?Three common types of intrusion are sills, dykes, and batholiths (see image below).
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