11496433
Description
Mind Map by Zubayr C-137 Rashid, updated more than 1 year ago
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Created by Zubayr C-137 Rashid
about 7 years ago
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8.4-Metamorphic Rocks
- Formation of Metamorphic Rocks
- Metamorphic rocks form
when intense heat and/or
pressure alter existing rocks.
- When intense heat and/or pressure alter existing rocks,
it may cause physical changes
- The process called shearing is the folding of rocks or
sliding different parts of rock sideways in a process
called shearing.
- Heat and pressure can also cause chemical changes, such as
recrystallisation minerals. New minerals such as the semiprecious
gemstone garnet may form during this process.
- As rocks get buried deeper, the temperature & pressure increase. Heat & Pressure can also
increase the movement of the Earths Crust. The crust is broken into massive plates, called
tectonic plates.
- The formation of rocks is called
metamorphism.
- Metamorphic rocks form
when intense heat and/or
pressure alter existing rocks.
- Types Of Metamorphism
- Regional Metamorphism- this is where rock is altered by both heat & pressure.
This kind of metamorphic change often occurs across large areas as a result of
colliding plates or rocks being buried.
- Contact Metamorphism- this is where rock is altered mostly by heat,
It often occurs over smaller areas as a result of hot magma intruding
into rock.
- Dynamic Metamorphism- this is where the rock is altered mostly by
heat. It often occurs over a small area where the crustal rocks are
scraping past each other.
- Regional Metamorphism- this is where rock is altered by both heat & pressure.
This kind of metamorphic change often occurs across large areas as a result of
colliding plates or rocks being buried.
- Metamorphic Changes
- The texture of a rock can be changed by metamorphism.
One common change for a rock placed under heat &
pressure is that it becomes foliated.
- Foliation is the movement of minerals into layers or
bands.Pressure can also squash & crumple layers or bands, making them wavy.
- Not all metamorphic rocks are foliated.
Examples of non-foliated metamorphic rocks
are marble & quartzite.
- At the temperature of over 1000, the carbon can
crystallise into diamond. Diamonds can be
transported to the surface millions of years later
by fast moving magma
- The texture of a rock can be changed by metamorphism.
One common change for a rock placed under heat &
pressure is that it becomes foliated.
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