Chapter 7

Question 1

Metamorphism

Answer 1

The transformation of rocks as the result of heat, pressure, and/or fluid activity. Occurs below the melting point in the solid state.

Question 2

Metamorphism factors

Answer 2

heat, pressure, fluid activity

Question 3

Metamorphic grade

Answer 3

Degree of metamorphic change a rock has undergone. Higher closer to a Pluton.

Question 4

Index Minerals

Answer 4

Certain minerals that are known to only form under specific temperatures and pressure at a particular bulk composition (protolith)

Question 5

Foliated texture

Answer 5

Metamorphic rocks with minerals lined up in planes like stripes

Question 6

Nonfoliated texture

Answer 6

Metamorphic rocks that don’t have minerals lined up in planes like stripes

Question 7

Contact metamorphism

Answer 7

Rock minerals and textures are changed at high heat and low pressure due to contact with magma

Question 8

Impact metamorphism

Answer 8

Rock minerals and textures are changed by impact structures (meteors, underground nuclear explosions)

Question 9

Dynamic metamorphism

Answer 9

Rock minerals and texture changed as a result of high shear stress along fault zone, occurs at low temperature.

Question 10

Regional metamorphism

Answer 10

Rock minerals and texture changed over a large area. Occurs during tectonic events.

Question 11

Barrovian metamorphism

Answer 11

Regional, protolith is pelitic (shale)

Question 12

Regional metamorphism grades

Answer 12

First appearance of a mineral indicates the minimum temperature-pressure conditions that the rock experienced. (Chlorite = low grade; Biotite and garnet = intermediate grade; Sillimanite = high grade)

Question 13

Metamorphic zones

Answer 13

Areas with the same degree of metamorphism

Question 14

Shield

Answer 14

Area where Pre-Cambrian (older than 542 Ma) igneous/metamorphic rocks are exposed at the surface.

Question 15

Platform

Answer 15

Area where igneous/metamorphic basement overlain by sedimentary rocks

Question 16

Cratons

Answer 16

Shields and platforms

Question 17

Metamorphism limits

Answer 17

Lower temperature limit between 100-150°C, no agreement for a pressure lower limit. Upper boundary is melting (700-900°C)

Question 18

Metamorphism facies and P-T path

Answer 18

Defines metamorphic grade in terms of a group of minerals and doesn’t require that metamorphism began from the same rock.
As material is buried it undergoes prograde metamorphism. Pressure Increases Quickly, but temperature rises slowly. If Material is then uplifted and expose it undergoes retrograde metamorphism.

Question 19

Metamorphic rocks allignment

Answer 19

Differential stress.