METAMORPHIC ROCKS

1
METAMORPHIC ROCKS

• Form when heat and/or pressure change existing
  rock into a new rock through recrystallization
• Types of Metamorphism
• Regional Metamorphism
• occurs over a large area where rocks are buried
  deeply or are caught in a mountain building event
• rocks recrystallize due to high T P
• Contact Metamorphism
• occurs when rocks are locally exposed to high
  temperatures in a small area (e.g. under a lava
  flow, at a meteorite impact site, etc.)

2
METAMORPHIC ROCKS

• classified by texture origin rock / composition
• Texture
• FOLIATED layered or banded
• foliation forms when long mineral crystals line
  up in response to pressure
• or when light and dark minerals separate
• NONFOLIATED not layered or banded
• no foliation forms when mineral crystals do not
  have a long axis
• and when only a few similar minerals are present

3
METAMORPHIC ROCKS

• classified by texture origin rock / composition
• Origin Rock / Composition
• origin / parent rock ? metamorphic rock
• sandstone ? quartzite (nonfoliated)
• conglomerate ? metaconglomerate (nonfloliated)
• limestone ? marble (nonfoliated)
• shale ? slate ? schist ? gneiss (foliated)
• granite ? schist ? gneiss (foliated)
• basalt ? amphibolite OR schist ? gneiss (rock
  names!) (foliated)