Metamorphic Rocks Quiz: Neomorphism Explained

Study Notes

Metamorphic rocks are formed when pre-existing rocks undergo changes due to heat, pressure, or chemically active fluids without melting.
Recrystallization converts small crystals of a mineral into fewer, larger crystals of the same mineral.
Neomorphism involves recrystallizing minerals and forming new minerals from the same chemical elements.
Metasomatism involves the addition or loss of chemical elements, resulting in new minerals from the original elements.

Contact Metamorphism: Occurs in localized areas near large igneous intrusions and along fractures that come into contact with hot fluids.
Regional Metamorphism: Occurs over larger areas due to intense pressure and heat, typically associated with deep burial and major igneous intrusions.

Foliated Metamorphic Rocks: Characterized by parallel planes of platy or elongated minerals, leading to bands or foliation. Increased metamorphism enhances foliation.
Nonfoliated Metamorphic Rocks: Lack a layered appearance. Examples include marble, quartzite, and anthracite.

The rock cycle illustrates the interrelationship among igneous, sedimentary, and metamorphic rocks.
Igneous rocks can transform into sedimentary or metamorphic rocks.
Sedimentary rocks can become igneous or metamorphic.
Metamorphic rocks can change into any of the three rock types.

Illustrates the relative stability and weathering rates of various minerals, roughly inverse to the crystallization sequence of minerals in Bowen's reaction series.

Weathering breaks down rocks at Earth's surface through rainwater action, temperature fluctuations, and biological activities.
Mechanical Weathering: Breaks down rocks into smaller pieces without changing their chemical composition due to temperature, pressure, and biological factors.
Example: Rocks by the sea changing shape due to water force during high tide.

A rock is defined as an aggregate of minerals, which may include organic matter.
The geosphere is primarily made of rocks.

Igneous Rocks: Formed from cooling of molten magma; can be intrusive (slow cooling, large crystals) or extrusive (fast cooling, small crystals).
Sedimentary Rocks: Formed from pre-existing rocks or fossils.
Metamorphic Rocks: Formed from existing rocks through heat and pressure.

Igneous rocks form from the cooling of magma or lava.
Intrusive Igneous Rocks: Form deep within the Earth, characterized by larger crystals due to slower cooling.
Extrusive Igneous Rocks: Form at the Earth’s surface, resulting in smaller crystals from rapid cooling.

Refers to rapid cooling of molten rock, potentially resulting in a glassy texture, as seen in volcanic glass and obsidian. This typically occurs during explosive volcanic eruptions.