- Slides: 19
Metamorphic Rocks • Form from heat, pressure, and hot liquids (fluids) • Metamorphic comes from Greek words meaning "change" and "form".
Metamorphic Rocks • Form 12 -16 kilometers beneath Earth • Changes at temperatures of 100°C - 800°C • If you squeeze and heat a rock for a few million years, it can turn into a new kind of rock. Metamorphic Rock
Where does the heat come from? 1. Leftover heat from the formation 2. Radioactive Decay – radioactive elements like uranium decay and release heat Earth produces almost as much heat as it’s losing!
Where does the pressure come from? • Layers of rock piled on top of layers and layers of rock. • The layers on the bottom get squeezed. • The thicker the layers, the more pressure there is.
Can form in 2 ways: 1. Contact Metamorphism • Rocks changes when in close contact to magma chambers • Hot fluids (water, carbon dioxide) can dissolve some elements in rock and change the composition ! t l e M t o N s e Do Just in close contact with Magma!
Deep underground, zones of metamorphism form around the hot magma of batholiths.
2. Regional Metamorphism • Pieces of the lithosphere crash into each other • Rocks get squished and change deep within mountain ranges • Pieces of crust can also be pulled below another and altered by high pressure and temperature Rocks d e s o h p r o m a t me s a e r a e g r a l r e v o f o e z i s e h t e r a that n e v e r o s e t a t many s ! s e i r t n u o c l a r seve
How could this happen? What force has the power to change all those rocks?
Common Metamorphic Rocks Classification Foliated (Banded) Non-Foliated (Not Banded) Metamorphic Rock Parent Rock Common Minerals Slate Shale, mudstone Quartz, clay minerals (feldspars) Schist Shale, slate, basalt, or granite Mica, chlorite, talc, quartz Gneiss Shale, schist, granite, sandstone, and other rock types Quartz, feldspars Quartzite Sandstone Quartz Marble Limestone, dolomite Calcite Anthracite coal Bituminous coal Crystalline carbon
Slate formed from shale
Schist formed from shale, slate, basalt, or granite
Quartzite formed from sandstone
• Classified according to composition & texture • Foliated texture - mineral grains line up in parallel layers to exhibit banding or layering (ex. slate & gneiss) • Non-foliated texture - mineral grains grow and rearrange but do not form layers (ex. quartzite) gneiss Slate quartz
• Foliated or Banded Rock – minerals are lined up parallel to the surface; can appear striped • Flattened minerals • Folded Layers • Sparkly, shiny thin layers • Looks like it is one solid color (homogenous)