Metamorphism and Foliation Overview

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Questions and Answers

What is foliation?

Layering of igneous rocks.

Alignment of any kind observed in any kind of rocks.

An alignment of mineral grains in a metamorphic rock. (correct)

Layering observed in sedimentary rocks.

Foliated metamorphic rocks are never:

Low grade.

High-grade.

Foliated.

Caused by contact with magma. (correct)

Shearing is a type of:

Compressive stress.

Differential stress. (correct)

Lithostatic pressure.

Confining pressure.

Metamorphic rocks with a planar texture (minerals are aligned within the rock) are:

Foliated. Signup and view all the answers

Metamorphic rocks are classified primarily according to:

Texture - the presence/absence of foliation. Signup and view all the answers

Which of the following is a non-foliated metamorphic rock?

Quartzite. Signup and view all the answers

The major difference between metamorphism and metasomatism is:

Metasomatism is metamorphism with the introduction of additional ions from an external source. Signup and view all the answers

Ore bodies at divergent plate margins can be formed by:

Hydrothermal processes. Signup and view all the answers

Metamorphic rocks with the same mineral assemblage belong to the same:

Metamorphic facies. Signup and view all the answers

A metamorphic rock that has undergone partial melting to produce a hybrid metamorphic-igneous rock is called:

Migmatite. Signup and view all the answers

Which of the following lists is arranged in order from highest to lowest grade of metamorphic rock?

Gneiss, schist, phyllite, slate. Signup and view all the answers

The generally accepted temperature limits for metamorphism are:

200 degrees Celsius to rock melting. Signup and view all the answers

The principal agents of metamorphism are:

Heat and pressure. Signup and view all the answers

When rocks are metamorphosed, the mineral components of the rock are:

Transformed in the solid state. Signup and view all the answers

Contact metamorphism results whenever:

Magma is in contact with other rocks. Signup and view all the answers

Regional metamorphism:

All of these. Signup and view all the answers

Slate is a metamorphic rock type associated with:

Low pressure, low temperature conditions. Signup and view all the answers

Gneiss is a metamorphic rock associated with:

High temperature, high pressure conditions. Signup and view all the answers

Metamorphism of limestone may contribute to global warming by the release of:

Carbon dioxide. Signup and view all the answers

Study Notes

Foliation and Metamorphism

Foliation: Alignment of mineral grains in metamorphic rocks, resulting in a layered appearance.
Foliated Metamorphic Rocks: Not caused by contact with magma; typically formed under directed pressure.
Shearing: A form of differential stress that distorts rock shapes.

Classification of Metamorphic Rocks

Metamorphic rocks are categorized based on texture, particularly the presence or absence of foliation.
Non-foliated metamorphic rock example: Quartzite, which lacks a layered structure.
Metamorphic Facies: Groups of metamorphic rocks that share the same mineral assemblage, indicating similar metamorphic conditions.

Processes Involved in Metamorphism

Metasomatism: A process that involves the introduction of additional ions, distinguishing it from regular metamorphism.
Hydrothermal Processes: Can form ore bodies at divergent plate margins, involving mineralization from hot, mineral-rich water.
Contact Metamorphism: Occurs when magma contacts surrounding rocks, leading to changes due to heat.

Conditions and Agents of Metamorphism

Metamorphism typically occurs between 200 degrees Celsius and the onset of rock melting.
Principal agents of metamorphism include heat and pressure, which facilitate mineral transformation.
When rocks metamorphose, their mineral components are transformed in a solid state without melting.

Types of Metamorphic Rocks and Grades

Grade of Metamorphic Rocks: The sequence from highest to lowest grade is gneiss, schist, phyllite, slate.
Slate: Associated with low pressure and low temperature conditions, making it less metamorphosed.
Gneiss: Formed under high temperature and high pressure conditions, indicative of significant metamorphic processes.

Impact on Climate

The metamorphism of limestone can release carbon dioxide, potentially contributing to global warming.

Summary of Regional and Contact Metamorphism

Regional Metamorphism: Produces foliated rocks over extensive areas under high temperature and pressure.
Contact Metamorphism: Results specifically from magma interaction with surrounding rocks.

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Description

Explore the concepts of foliation and metamorphism in this quiz, focusing on the alignment of mineral grains and the categorization of metamorphic rocks. Learn about different metamorphic processes, including metasomatism and hydrothermal actions, that play significant roles in rock transformation.