Metamorphic Rocks • What is a metamorphic rock? • Rocks, either igneous, sedimentary, and/or metamorphic, that have been changed in size, shape, texture, and even mineralogy by the application of heat, pressure, and chemically active fluids.
Metamorphic Rocks • The precursor to a metamorphic rock (what the rock type was before metamorphism) is known as the protolith.
Metamorphic Rocks • How are metamorphic classified? • Foliated - Parallel surfaces or apparent layers of minerals. • Non-foliated - The rock lacks any apparent layering.
Environments of Metamorphism Contact metamorphism - this is usually localized and occurs when magma comes into contact with surround rock. The rock surrounding the magma gets heated and changed.
Environments of Metamorphism Regional Metamorphism - occurs over a large area on the continents and is associated with mountain building epochs.
Environments of Metamorphism • Dynamic Metamorphism - occurs in fault zones and is the result of tectonic movement.
Environments of Metamorphism • Rifting Metamorphism - metamorphism associated with tectonic rifting events. • Mid-Ocean Ridges - metamorphism through heat and hot water at mid-ocean ridges. • Subduction Zone - The creation of blueschists, which are rare rocks.