Metamorphism of Sedimentary Rocks Sandstone: Quartzite, Metaquartzite Shale: Phyllite Slate Schist Gneiss Limestone: Marble
Types of Metamorphism Contact Metamorphism: The main metamorphic agent is heat.
Progression of metamorphism Start with a shale and then hit it with pressure and heat. Slate Phyllite Schist
Introduction to Metamorphic Rocks Metamorphism is the solid-state transformation of pre-existing rock into texturally or mineralogically distinct new rock as the result of high temperature,high pressure, or both.
Metamorphic rocks have been changed from a pre-existing rock. • Caused by extreme heat and/or pressure.
Regional Metamorphism • Caused by extreme pressure and heat. • Happens over wide “regions”.
Contact Metamorphism • Caused by contact with extreme heat.
Types of Foliation: • Gneissic Foliation- minerals are squished into bands. “Zebra Stripes”
Banding vs. Layers Bands Layers
Schistose foliation- • minerals have been squashed into flakes of mica.
Slaty foliation- • Rock splits into flat, thin layers.
Slate + + = Phyllite
Phyllite + + = Schist
Schist + + = Gneiss
How does Metamorphism Relate to Plate Tectonics? T and P increase at collisional (convergent) plate boundaries.