metamorphismppt2

Metamorphism

A change in form of pre-existing rocks of all types through heat, pressure, or both.

Contact Metamorphism

Metamorphism that occurs due to the action of heat alone, typically associated with large igneous bodies.

Dynamic Metamorphism

Metamorphism that occurs due to pressure alone, often associated with fault planes.

Metamorphic Grade

The extent to which pre-existing rocks have been altered, classified as low, medium, or high grade.

Metamorphic Aureole

The volume of country rock surrounding an igneous intrusion that has been affected by heat.

Isochemical

Describes metamorphic changes where the bulk chemical composition of the parent rock and metamorphic product are identical.

Pelites

Argillaceous rocks that have undergone metamorphism.

Granoblastic Texture

A texture where all crystals in a metamorphic rock are roughly the same size.

Foliation

The banding or layering in metamorphic rocks that results from the directed stress during metamorphism.

Slate

A low-grade metamorphic rock formed under conditions of moderate pressure and low temperature.

Schist

A medium-grade metamorphic rock characterized by the presence of large mica crystals.

Gneiss

A high-grade metamorphic rock with distinct banding, formed under high temperature and pressure.

Migmatite

A very high-grade metamorphic rock that is a mix of metamorphic and igneous material.

Cataclasis

The process of crushing and grinding of rocks due to high pressure.

Hornfels

A high-grade metamorphic rock that does not show original sedimentary structures and has a tough, crystalline texture.

Metaquartzite

A metamorphic rock formed from sandstone, showing a granular texture with coarser quartz grains.

Marble

A metamorphic rock formed from limestone, characterized by a granoblastic texture and loss of original structures.

Porphyroblasts

Large crystals that form in a finer-grained matrix within a metamorphic rock.

Thermal Metamorphism

Metamorphism resulting from heat from an igneous intrusion.

Regional Metamorphism

Metamorphism that occurs over large areas due to increases in pressure and temperature, usually associated with tectonic processes.

Chiastolite

A medium-grade metamorphic mineral often found in Chiastolite Rock, characterized by needle-like crystals.

Biotite Mica

A common phyllosilicate mineral in schists and gneisses, contributing to the schistose texture.