metamorphic rocks (8) Flashcards Preview

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Flashcards in metamorphic rocks (8) Deck (38)
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1
Q

Parent Rock

A

The rock from which a metamorphic rock formed

2
Q

Metamorphism

A

The changes in mineral composition and texture of a rock subjected to high temperature and pressures within Earth

3
Q

Metamorphic Grade

A

Degree to which a metamorphic rock changes from temperature and pressure

4
Q

Recrystallization

A

The formation of new mineral crystals in a rock that tend to be larger than the original crystals

5
Q

Geothermal Gradient

A

The gradual increase in temperature with depth in the crust. The average is 30degrees C/km in the upper crust

6
Q

Confining Pressure

A

Stress that is applied uniformly in all directions

7
Q

Differential Stress

A

Forces that are unequal in different directions

8
Q

Compressional Stress

A

Differential stress that shortens a rock body

9
Q

What are four agents that drive metamorphism?

A

Heat
Confining Pressure
Chemically Active Fluids
Differential Stress

10
Q

This agent of metamorphism is most important?

A

Heat

11
Q

What characteristic of a metamorphic rock is determined primarily by its parent rock?

A

Composition

12
Q

Texture

A

The size, shape, and distribution of the particles that collectively constitute a rock

13
Q

Foliation

A

A term for a linear arrangement of textural features often exhibited by metamorphic rocks

14
Q

Solid-State Flow

A

The solid-state flow of rock that occurs when rocks are exposed to extreme conditions of heat and pressure

15
Q

Rock Cleavage

A

The tendency of rocks to split along parallel closely spaced surfaces. These surfaces are often highly inclined to the bedding planes in the rock

16
Q

Salty Cleavage

A

A type of foliation that is characteristic of slates, in which there is parallel arrangement of fine-grained metamorphic minerals

17
Q

Gneissic Texture

A

A texture of metamorphic rocks in which dark and light silicate minerals are separated, giving the rock a banded appearance

18
Q

Nonfoliated

A

Describes metamorphic rocks that do not exhibit foliation

19
Q

Porphyroblastic Texture

A

A texture of metamorphic rocks in which particularly large grains (porphyroblasts) are surrounded by a fine-grained matrix of other minerals

20
Q

Slate

A

Foliated, fine grained, excellent rock cleavage (salty)

21
Q

Phyllite

A

Foliated, fine grained, glossy sheen

22
Q

Schist

A

Foliated, medium-to-coarse grained, micas dominate

23
Q

Gneiss

A

Foliated, coarse grained, banding of dark and light

24
Q

Marble

A

Nonfoliated, medium-to-coarse grained, soft

25
Q

Quartizite

A

Nonfoliated, medium-to-coarse grained, hard, quartz

26
Q

Hornfels

A

Nonfoliated, fine grained, tough, dark

27
Q

Contact Metamorphism

A

Changes in rock caused by the heat from a nearby magma body

28
Q

Aureole

A

A zone or halo of contact metamorphism found in the country rock surrounding an igneous intrusion

29
Q

Hydrothermal Metamorphism

A

Chemical alterations that occur as hot, ion-rich water circulates through fractures in rock

30
Q

Burial Metamorphism

A

Low-grade metamorphism that occurs in the lowest layers of very thick accumulations of sedimentary strata

31
Q

Regional Metamorphism

A

Metamorphism associated with large-scale mountain building

32
Q

Impact Metamorphism

A

Metamorphism that occurs when meteorites strike Earth’s surface

33
Q

What are 3 rocks that are produced by contact metamorphism?

A

Hornfels
Quartzite
Marble

34
Q

What is the agent of hydrothermal metamorphism?

A

Hot water full of dissolved ions

35
Q

Which type of plate boundary is associated with regional metamorphism?

A

Convergent

36
Q

Index Mineral

A

A mineral that is a good indictor of the metamorphic environment in which it formed. Used to distinguish different zones of regional metamorphism

37
Q

Migmatite

A

A rock exhibiting both igneous and metamorphic rock characteristics. Such rocks may form when light-colored silicate minerals melt and then crystallize, while the dark silicate minerals remain solid

38
Q

Metamorphic Facies

A

A group of associated minerals that are used to establish the pressures and temperatures at which rocks undergo metamorphism