intrusive igneous rocks explain
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Answer:
Igneous rock (derived from the Latin word ignis meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust.
Volcanic eruptions of lava are major sources of igneous rocks. (Mayon volcano in the Philippines, erupting in 2009)
Natural columns of igneous rock separated from each other by columnar joints, in Madeira
Contents
Geological significance
Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earth's crust by volume.[1] Igneous rocks form about 15% of the Earth's current land surface.[note 1] Most of the Earth's oceanic crust is made of igneous rock.
Igneous rocks are also geologically important because:
their minerals and global chemistry give information about the composition of the mantle, from which some igneous rocks are extracted, and the temperature and pressure conditions that allowed this extraction, and/or of other pre-existing rock that melted;
their absolute ages can be obtained from various forms of radiometric dating and thus can be compared to adjacent geological strata, allowing a time sequence of events;
their features are usually characteristic of a specific tectonic environment, allowing tectonic reconstitutions (see plate tectonics);
in some special circumstances they host important mineral deposits (ores): for example, tungsten, tin, and uranium are commonly associated with granites and diorites, whereas ores of chromium and platinum are commonly associated with gabbros.
Geological setting
Formation of igneous rock
In terms of modes of occurrence, igneous rocks can be either intrusive (plutonic and hypabyssal) or extrusive (volcanic).
Intrusive
Basic types of intrusions:
1. Laccolith
2. Small dike
3. Batholith
4. Dike
5. Sill
6. Volcanic neck, pipe
7. Lopolith
Note: As a general rule, in contrast to the smoldering volcanic vent in the figure, these names refer to the fully cooled and usually millions-of-years-old rock formations, which are the result of the underground magmatic activity shown.
Intrusive igneous rocks make up the majority of igneous rocks and are formed from magma that cools and solidifies within the crust of a planet (known as plutons), surrounded by pre-existing rock (called country rock); the magma cools slowly and, as a result, these rocks are coarse-grained. The mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite.
The central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores (called batholiths) may occupy huge areas of the Earth's surface.
Intrusive igneous rocks that form at depth within the crust are termed plutonic (or abyssal) rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks and they are usually medium-grained. Hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths.
Answer:
There are 3 kinds of rocks
Igneous Rock
Metamorphic Rock
Sedimentary Rocks
Igneous Rock is formed when molten lava cools down either Inside or outside the surface those rock which are formed inside the lava is called intrusive Igneous Rock and those which are formed outside is called extrusive igneous rock
Sedimentary rocks are formed in two way 1st by erosion, weathering and deposion and 2nd by Rock clash or when rocks clash with each other and they break to form sedimentary rocks
Metamorphic Rocks are formed when rocks are exposed to great and high pressure
The changing of different kinds of rocks into other rocks is called Rock cycle like both igneous and metamorphic rocks can change into sedimentary rocks in the same way each kind of rock can change into other 2 kind of rocks and this is called rock cycle.