Metamorphic Rock and Rock Cycle

Practice flashcards covering the definition, causes, classification, and locations of metamorphism, as well as the rock cycle.

What is the literal meaning of the word 'Metamorphism'?

'Meta' means change and 'morph' means form.

Does metamorphism involve the melting of rock?

No, it is a solid state change with no melting; if the rock melts, it becomes an Igneous rock.

What is the term for the original rock before it undergoes metamorphism?

The parent rock, or Protolith.

What is the temperature range required for metamorphism to occur?

Between $200^{\circ}C$ and $800^{\circ}C$.

What are the three primary sources of heat that cause metamorphism?

Magma (subsurface heat), Deep burial (rocks in a basin), and Friction (subduction zones or meteorites).

How does confining pressure differ from differential stress?

Confining pressure is equal in all directions, while differential stress is pressure applied in one direction.

What is the relationship between the direction of pressure and the orientation of foliations?

The direction of the pressure is perpendicular to the foliations.

How is the degree of metamorphism classified based on temperature and pressure?

Low grade ($200^{\circ}C - 400^{\circ}C$ + low pressure), Intermediate grade ($400^{\circ}C - 600^{\circ}C$ + moderate pressure), and High grade ($>600^{\circ}C$ and/or very high pressure).

What are the characteristics and common use of Slate?

It is a fine-grained, dull, low-grade metamorphic rock that breaks into planes; it is commonly used for blackboards.

What is the parent rock for Slate, Phyllite, and Schist?

Shale or Mudstone.

How can Phyllite be distinguished from Slate?

Phyllite has a shiny appearance and a wrinkled surface.

Which foliated rock is characterized by 'zebra stripes' or bands of felsic and mafic minerals?

Gneiss.

What causes the 'fizzing' reaction when testing Marble with an acid bottle?

Marble is highly packed with calcite crystals which react to the acid.

What is the parent rock and texture of Quartzite?

The parent rock is Sandstone, and it has a sugary texture with visible quartz grains.

How can Anthracite be distinguished from Obsidian?

Anthracite is very brittle, can be broken with fingers, and cannot scratch glass, unlike Obsidian.

What characterizes Regional Metamorphism?

It is associated with mountain building (convergent boundaries), produces large quantities of rock, and involves low to medium temperature with high pressure.

What is 'Contact Metamorphism' and what is an 'aureole'?

Contact metamorphism is caused by magma intrusion (high temperature, low pressure); an aureole is the ring of metamorphic rocks that may form around the magma.

What is the average geothermal gradient?

The rate at which Earth's interior temperature increases with depth, averaging $25^{\circ}C/Km$.

What unique materials can form during Meteorite (Shock) Metamorphism?

Tiny diamonds and coesite (a dense type of quartz).

Why are igneous rocks referred to as 'primary rocks' in the rock cycle?

Because they form directly from lava and magma.

Why are sedimentary and metamorphic rocks referred to as 'secondary rocks'?

Because they are formed from pre-existing igneous rocks.