Metamorphic Rocks and Processes

A series of flashcards covering key terms and concepts related to metamorphic rocks and their formation processes.

Metamorphism

The process by which rocks change due to heat, pressure, and chemically active fluids.

Protolith

The original rock from which a metamorphic rock is formed.

Foliation

A layered texture in metamorphic rocks caused by differential stress.

Lithification

The process of turning sediments into sedimentary rock through compaction and cementation.

Thermal gradient

The rate at which temperature increases with depth in the Earth, approximately 25-30 °C per kilometer.

Temperature and pressure increase with _____

depth

Lithostatic stress

Equal pressure applied to rock from all directions due to the weight of overlying material.

Differential stress

Unequal stress due to tectonic forces applied to a rock that can cause deformation.

Metamorphic grade

A classification reflecting the intensity of metamorphism, which affects crystal size and texture.

Porphyroblast

Large mineral crystals that form in a finer-grained matrix in metamorphic rocks.

Index minerals

Minerals used to determine the metamorphic grade of rocks based on their stability at certain pressure and temperature conditions.

Diagenesis

The process involving the physical and chemical changes to sediments after they have been deposited.

Geothermal gradient

The rate of temperature increase in the Earth's crust with depth.

Amphibolite

A metamorphic rock formed predominantly from basalt and characterized by amphibole minerals.

Gneiss

A high-grade metamorphic rock with a banded appearance produced by high temperature and pressure.

Schist

A medium to high-grade metamorphic rock with a pronounced foliation and larger crystal sizes.

Slate

A low-grade metamorphic rock derived from shale, characterized by its ability to split into thin layers.

Quartzite

A non-foliated metamorphic rock composed primarily of quartz.

Marble

A non-foliated metamorphic rock formed from limestone.