Download IGNEOUS ROCKS - Sri Venkateswara College of Engineering

IGNEOUS ROCKS
DEFINITION
Igneous rocks are formed out of hot larva or
magma.
The extruded larva on solidification over the
earth’s surface gives rise to extrusive igneous
rock.
The magma on solidification below the earth’s
surface is called intrusive rock.
MOLTEN MAGMA
INTRUSIVE AN EXTRUSIVE
IGNEOUS ROCKS
INTRUSIVE IGNEOUS ROCK
• The molten magma under the earth’s surface
gets solidify there itself to form the intrusive
igneous rock.
• It has high pressure
and temperature.
it cools slowly
Also known as
plutonic rock.
Granite
EXTRUSIVE IGNEOUS ROCK
• When the molten magma goes out as volcano
and then solidify is known as extrusive
igneous rock.
• It cools relatively fast.
• It has high temperature and
pressure.
Rhyolite
COMPLEX IGNEOUS ROCK
• These rocks cools at the intermediate level
that is not above or below the earths surface.
Basalt
INTRUSIVE ROCK
CONCODANT
DISCORDANT
SILLS
When the magma solidifies as a thin
sheets or layers is called sills.
PHACOLITS
• When the magma is under low pressure it will
not exert much pressure to make space for
itself.
LACOLITS
• When the magma gets intruded into the layer
due to high viscosity it may not spread
eventually forming domes.
DYKES
• When the magma moves vertically hence
forming a wall like structure is known as
dykes.
VOLCANIC NECKS
• The magma gets solidified in the inactive
volcanic areas in the form of thick pipes is
called volcanic necks.
BATHOLITHS
• When the magma moving under high pressure
forming huge mass of igneous rock.
STRUCTURE OF IGNEOUS ROCK
primary
secondary
PRIMARY STRUCTURE
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Flow structure
Pillow structure
Blocky and ropy structure
Spherulitic structure
Orbicular structure
Rift and grain structure
Tension joints
Vesicular structure
Miarolitic structure
USES
• Granites posses excellent qualities of building
rocks for structural as well as architectural
purposes.
• They have high crushing strength.
• Has least porosity.
• Used in decorative purposes.
• Could get in variety of colours.
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