METAMORPHISM

• When existing rocks heat up, their temperature rises and they are penetrated with fluid from magma.
• Metamorphism refers to changes that take place within a rock as a result of it being subjected to conditions that are different from those in which it is formed.
• The term "Meta" refers to change. And is a greek word
• The term "morphe" means form, and it is derived from Greek words.
• Heat and pressure affect the changes in rocks.
• A metamorphic rock is formed at the surface of the earth through the process of metamorphism with recrystallization of minerals in rocks due to changes in temperature and pressure.
• Recrystallization of rocks means that atoms are reorganized resulting in changes of particle size, but mineral composition are still the same.
• High temperature and pressure lead to recrystallization.
• Foliation in metamorphic rock refers to layering due to the changes in crystal orientation during recrystallization.
• If the elongated crystals of minerals grow because of recrystallization that is perpendicular to the direction of force, it will create a foliated rock.
• If all pressure comes from all sides, it results in a non-foliated rock.
• Regional metamorphism is the transformation of large rocks due to high pressure and temperature beneath the earth.
• If these rocks in regional metamorphism go up and exposed due to erosion, they can be seen in large surface of lands.
• Regional metamorphism can occur in converging boundaries where plates continuously collide due to high heat and pressure.
• Rocks in the metamorphose zone are foliated and hard due to high pressure and recrystallization of minerals.
• Contact Metamorphism forms non-foliated metamorphic rock due to heat.
• Magma bakes the surrounding rocks due to differences in temperature - in CONTACT METAMORPHISM
• Deformed rocks with foliation/lineation is brought by pressure and recrystallization of minerals.
• Metamorphic rocks are the hardest rock.
• Contact Metamorphism is when rocks come into contact with heat, provided by lava or magma.
• In contact metamorphism, rocks that are burned by the heat of the magma is the metamorphic rock.
• All exposed rock will be burned, causing them to change (metamorphosize) into something new called METAMORPHIC ROCK.
• A NON-FOLIATED METAMORPHIC ROCK is formed in contact metamorphism.
• Regional Metamorphism is when rocks are subjected to pressure.
• Pressure increases with depth.

  • The higher the pressure, the greater the degree of metamorphism
• Temperature increases with depth, due to the geothermal gradient.

  • If rocks are buried within the earth, the deeper the rock gets, the higher the temperature
• Medium-grade metamorphism is at 320-450 °C.
• Regional Metamorphism is caused by large geologic processes such as mountain-building and is associated with convergent plate boundaries and formation of mountain ranges.
• Foliated metamorphic rocks are formed from mudstones and contain "fine-grained" or "platy" minerals that are usually too small to see with the naked eye.
• Examples of hydrous minerals include Clay Minerals, Serpentine, Chlorite.
• Examples of hydrous minerals that disappear at highest grade metamorphism include Muscovite and Biotite.
• The fluid phase is a chemically active fluid that is mostly water with dissolved ions.
• As the temperature and pressure increases, on a body of rock then grade of metamorphism increases.
• The higher the pressure, the greater the degree of metamorphism.
• The chemical composition of parent rock is the same as metamorphic rock.
• Foliated metamorphic rocks have a layered/banded appearance that is produced by exposure to heat and direct pressure.
• Pressure is applied to rocks in three ways: Pore pressure, Load pressure, and Tectonic Pressure.
• Non-foliated metamorphic rocks have no evident planar fabric on foliation, crystallized under conditions where there were no differential stress and are comprised of minerals.
• Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.
• Low-grade metamorphism is at 200-320 °C.