The metamorphism is a part of the geological cycle. Metamorphism changes the physical and chemical structure of rocks. It could be classified as per dominant agent responsible and following is a brief list of it.
- Thermal metamorphism
- Dynamic or Clastic metamorphism
- Dynamo thermal metamorphism
- Plutonic metamorphism
- Geothermal metamorphism
Also known as heat metamorphism, it’s because high heat, that changed the properties of the rock.
Following are the subtypes of thermal metamorphism.
- Contact metamorphism
This type of metamorphism occurs due to the continuous contact of stone with magma.
This is also due to contact with magma but it’s more rapid than contact metamorphism.
- Optalic metamorphism
This is because of the contact of magma with adjacent rocks.
- Pneumatolytic metamorphism
This is also called injection metamorphism and is because of the influx of magma in the present bed of rock.
- Contact metamorphism
Dynamic or clastic metamorphism
In this type of metamorphism direct pressure is predominant. A few examples are beds of rock at bottom of an ocean.In the dynamic metamorphism, there is little or no change in the chemical structure of the rock, only physical changes are there.
Amongst all types of metamorphism, the study of this type of metamorphism is most important as it causes a widespread of regional metamorphic changes.
The predominant agents, that cause this is both, the heat and the pressure to a substantial degree.
This type of metamorphism may create new folds and results in the creation of new minerals.
In this type of change in the chemical and physical structure of rock, the agents that play the predominant role are uniform pressure and heat. It occurs deep inside the earth’s crust.
This type of metamorphism tends to change rocks into more dense minerals. One of the examples is the marble stone from the limestone.
Geothermal metamorphism (Uniform pressure is predominant)
Usually, this type of metamorphism doesn’t change any properties in silicate stones. This type of metamorphism is found in the ocean bed.
Changes that could be observed in a metamorphism yield rocks.
- Crystallization of calcareous sedimentary rocks (i.e. limestone)
- Recrystallization of igneous rocks
- Formation of drag folds, joints etc.
- Formation of new minerals.