Transcript What Happened in Hawaii?

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.)
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
METAMORPHIC ROCKS
classified by texture & origin rock / composition
• Origin Rock / Composition
→ 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)
– origin / parent rock
http://rst.gsfc.nasa.gov/Sect2/rock_cycle_800x609.jpg
http://www.physicalgeography.net/fundamentals/images/rockscycle.GIF