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Metamorphic Rock. The changes or alterations of rock in terms of texture or mineralogy from the pre-existing rock is caused by: Temperature Pressure Chemical environment changes. Metamorphism. Another factor that affects the metamorphism is the original or parent rock.
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The changes or alterations of rock in terms of texture or mineralogy from the pre-existing rock is caused by: • Temperature • Pressure • Chemical environment changes Metamorphism
Another factor that affects the metamorphism is the original or parent rock.
There are numerous combinations of metamorphic rocks. • The first characteristic is to look at the texture of the rock: • Foliated • Non-foliated Classification of Metamorphic Rock
The alignment of minerals in a rock subjected to increased pressure is called foliation.. • This involves rocks with two or more crystals. Foliation
Pressure will cause the material to compact. The type of pressure will dictate the alignment of the minerals; foliation. Pressure Effects
The type of minerals will determine the type of new rock formed. • If only one mineral is found in the parent rock, when it undergoes metamorphism the composition remains the same but the crystals grow larger. • More that one mineral present, re-crystallization can take place making for new minerals. Mineralogy
The two main types are: • Contact metamorphism, and • Regional metamorphism. Types of Metamorphism
These rocks are formed during metamorphism usually without significant differential stress but with high temperature. • Contact metamorphism occurs in country rock (rock surrounding the magma) immediately adjacent to intruded magmas. Contact Metamorphism
This is the most common source of metamorphic rock of the Earth’s crust. • It involves occurring at great depths. • Pressure, temperature and the chemical environment of the original rock are all altered. Regional Metamorphism
This is the term given to the intensity of metamorphism that a mineral has been subjected. • Lots of heat, pressure and chemical change it would be considered a high metamorphic grade. Metamorphic Grade
The impact of meteors can create a metamorphism called Shock metamorphism. • As the meteor strikes the earth it creates enough heat and melts local rock which are thrown up to 100km from the impact site. These rocks are called Tektites.