Download Metamorphic Rocks Types

Metamorphic Rocks
Types
• Form from pre-existing rocks (igneous, sedimentary,
other metamorphic)
• Chemically change under high heat, high pressure,
and/or chemical reactions with heated fluids
Hydrothermal
Metamorphism
• Super-heated fluids can change the composition of rocks
in contact.
• Areas near hydrothermal vents
• Or from areas
near active
volcanoes
Contact
Metamorphism
• Caused by extreme heat from magma
• Magma intrusions
Regional
Metamorphism
• Caused by extreme pressure over a large area (mountain
building)
Categorizing
Metamorphic Rocks
• Organized by texture and composition
• First divided into foliated and non-foliated
• Layers vs. Non-layered
Categorizing
Metamorphic Rocks
• Foliated
• Layers created during formation, crystals are squished
parallel to each other. Can often be broken into layers
• Examples – Schist (from shale) and Gneiss (from granite)
Schist
Gneiss
Categorizing
Metamorphic Rocks
• Non-Foliated
• Formed from blocky, interlocking crystals.
• Does not break into layers
• Examples: Quartzite (from sandstone) and Marble
(from limestone)
Quartzite
Marble
Categorizing
Metamorphic Rocks
• Additional Descriptions
• foliated
– gneissic- alternating bands of color
– schistose-intermixed colors
– Slaty-very fine smooth planes, easy to split,
grey or green
• non foliated
– granoblastic-large rounded pieces
– Hornfelsic- sharp angular pieces
Rock Cycle
• Forces that breakdown
– Melting
– Weathering: chemical (alters structure of a mineral) or
mechanical (physical breakdown)
– Erosion
*Igneous rocks - more common on earth (most are
below ground).
*Sedimentary rocks are most common above ground
Rock Cycle
• Forces that form
– Cooling
– Deposition, Compaction, Cementation
– Pressure
Rocks
• Continuous process with no set pathway