Lecture 12: Metamorphic Rocks

These flashcards cover key vocabulary and concepts related to metamorphic rocks, their formation processes, and characteristics.

Metamorphism

The process by which a parent rock (protolith) is transformed into a metamorphic rock through heat, pressure, and/or chemically active fluids.

Protolith

The original rock from which a metamorphic rock forms.

Heat-related metamorphism

Metamorphism that occurs due to increased temperature, often associated with burial or contact with hot magma.

Foliation

A texture in metamorphic rocks that results from the alignment of elongated minerals under differential stress.

Slate

A low-grade metamorphic rock formed from shale, characterized by its foliated texture.

Gneiss

A high-grade metamorphic rock characterized by its banded appearance and composition of alternating layers of light and dark minerals.

Regional metamorphism

Metamorphism that occurs over large areas under conditions of high pressure and temperature, often associated with tectonic forces.

Contact metamorphism

Metamorphism that occurs when rocks are heated by proximity to molten magma, leading to localized changes without significant pressure increase.

Quartzite

A metamorphic rock formed from the metamorphism of sandstone, primarily made of quartz.

Marble

A metamorphic rock formed from the metamorphism of limestone, known for its crystalline texture and composition of calcite.

Recrystallization

The process during metamorphism where minerals change size and shape without melting, resulting in new crystal structures.

Grades of metamorphism

Classification based on temperature and pressure, including low grade (low temp/pressure), intermediate grade (moderate), and high grade (high temp/pressure).

Mafic and felsic minerals

Mafic minerals are dark and rich in iron and magnesium, while felsic minerals are light and rich in silica. Mafic minerals typically resist metamorphism more than felsic.