Transcript Metamorphic Rocks

Metamorphic Rocks
SWBAT compare and contrast the different
types and causes of metamorphism;
distinguish among metamorphic textures;
explain how mineral and compositional
changes occur during metamorphism;
understand how rocks continuously change
from one type to another in the rock cycle
Types of Metamorphism
• How do metamorphic rocks form?
– Pressure and temperature are not enough to
melt a rock, but alter the texture, mineralogy,
or chemical composition of a rock.
• Regional metamorphism
– High temperature and pressure affect large
regions of Earth’s crust.
Types of Metamorphism
• Contact metamorphism
– Molten rock come in contact with solid rock,
without melting the contact rock.
• Why is contact metamorphism usually
limited to thin zones?
– Lava cools too quickly for the heat to
penetrate into the surface rocks.
Types of Metamorphism
• Hydrothermal metamorphism
– Hydro – water
– Thermal - heat
– Very hot water reacts with rock and alters its
chemistry and mineralogy
Metamorphic Textures
Foliated
Metamorphic rocks with wavy
layers and band of minerals, in
long needle like crystals.
Nonfoliated
Lack mineral grains with long axes
in one direction. Composed of
minerals that form with blocky
crystal shapes
Metamorphic Textures
• Porphyroblasts
– New metamorphic minerals that grow quite
large
• What is the rock cycle?
– The continual change of rocks from one type
to another.
Rock Cycle
Igneous rock
Sedimentary
rock
Heat and pressure
Weathering,erosion
Lithification
Metamorphic
rock