ERTH 101: Exploring Planet Earth - Week 7: Metamorphic Rocks

These flashcards cover key vocabulary related to metamorphic rocks and processes.

Metamorphism

The process of solid-state change in a preexisting rock (protolith) in response to changes in temperature and pressure.

Protolith

The original rock from which a metamorphic rock forms.

Lithification

The process whereby sediments compact under pressure, expel fluids, and gradually become solid rock.

Recrystallization

The process where mineral grains change in size and shape without changing their chemical composition.

Neocrystallization

The formation of new minerals in a rock undergoing metamorphism that were not present in the protolith.

Foliation

The alignment of platy minerals within a rock resulting in a planar fabric.

Contact Metamorphism

Metamorphism that occurs when rocks are heated by nearby molten magma.

Barrovian Metamorphism

A type of regional metamorphism characterized by progressive changes in mineral assemblages due to increasing temperature and pressure.

Blueschist Facies

A metamorphic rock facies formed under conditions of high pressure and low temperature.

Greenschist Facies

A metamorphic rock facies resulting from lower-grade metamorphism, typically associated with volcanic rocks.

Index Minerals

Minerals that are stable only within specific temperature and pressure conditions; used to indicate the metamorphic grade of rocks.

P-T Conditions

The pressure and temperature conditions at which metamorphic processes occur.

Metasomatism

The process in which a rock's chemical composition is changed by hydrothermal fluids.

Differential Stress

Stress applied unequally in different directions, influencing the texture and structure of metamorphic rocks.

Hydrothermal Metamorphism

Metamorphism that occurs when hot water interacts with rocks, altering their mineral composition.

Granulite

A high-grade metamorphic rock that forms under high temperature and pressure conditions.

Mylonite

A fine-grained metamorphic rock that forms in shear zones, characterized by a strong foliation.

Eclogite

A high-grade metamorphic rock formed under extremely high pressure and moderate temperature conditions, typically containing garnet and pyroxene.

Metamorphic Facies

A set of metamorphic conditions (temperature and pressure) that can be identified by the mineral assemblages present in the rock.

Prograde Metamorphism

Metamorphism that occurs as temperature and pressure increase, leading to the transformation of minerals.

Retrograde Metamorphism

Metamorphism occurring when rocks are brought back to lower temperature and pressure conditions, often requiring the addition of water.