Explain the procedure of Rock Formation Metamorphic Rocks?
Concept 1 : What is a metamorphic rock? First off, what does metamorphism mean? To morph is to change; a butterfly undergoes metamorphosis when it changes from a caterpillar into a butterfly. Rocks, too, can change as dramatically as the butterfly. Metamorphism in rocks is a change from the original rock type to a new rock type by the forces, or agents of change, within the Earth.
A metamorphic rock is a rock which has been chemically and/or structurally altered by forces within the Earth. Metamorphism occurs underground, as the agents of change are available inside the Earth's crust and mantle. There are three main agents that cause metamorphism to occur in rock:
Heat; heat is a major factor in the recrystallization of rocks within the hot interior of the Earth.
Pressure; pressure from the forces of miles of rock above, as well as stress from plate movement, faults, and forceful magma intrusions into the original rock body.
Chemical activity: chemical activity is the action of water and its dissolved ions on rock to chemically alter the structure and form a new rock. Water is the chief agent in the Earth's crust as a solvent, and the acidity or alkalinity within this water has a major effect on recrystallizing rock mineral structures.
Concept 2 : There are two main types of metamorphic rocks: foliated, and nonfoliated metamorphic rock. Foliated metamorphic rocks have layers or a layered or striped appearance. Slate is a common example of a foliated metamorphic rock (see image above). Slate has not undergone significant heat or pressure, and is similar to its original structure as a sedimentary deposit. We say slate has undergone low-grade metamorphism, meaning that it has been heated only slightly, and been squeezed somewhat by the pressure from the rock layers above. Phyllite is similar to slate, but has been metamorphized more significantly via intermediate-grade metamorphism. It has been heated up more and shows signs of recrystallization(see image above).
High-grade metamorphism involves the total remolding, compressing, and recrystallization of rock form one type, to a new type, which looks and feels very dissimilar to the original rock. An example of this is a schist, which is pictured at the bottom of this page. A schist is a metamorphized glob of shiny mica crystals which have been heated up considerably within the Earth's crust, then recrystallized into the rock pictured below, which is specifically known as a mica schist.