(MODULE 5) METAMORPHIC ROCK

Question 1

Rocks that are deeply buried melt (or partially melt) to form magma when temperatures are high enough. What happens to rocks that are deeply buried but are not hot enough to melt?

Answer 1

they undergo metamorphism

Question 2

___ refers to changes to rocks that take place in Earth’s interior. The changes may be new textures, new mineral assemblages, or both.

Answer 2

metamorphism

Question 3

transformations in metamorphism occur in the ___ state.

Answer 3

solid

Question 4

metamorphism can be interpreted as toasting a slice of bread. how so?

Answer 4

when the bread is toasted, it turns into toast. same material, different texture and composition.

the same goes with parent rock being exposed to heat and pressure to turn into metamorphic rock; same material, different texture and composition.

Question 5

The minerals present in a rock indicate its ___.

___ rocks formed under relatively cool temperatures and ___ rocks at high temperatures, whereas ___ rocks recrystallized at around the middle of the range of metamorphic temperatures.

Answer 5

1. metamorphic grade
2. low-grade
3. high-grade
4. medium-grade

Question 6

Factors controlling the characteristics of metamorphic rocks
1.
2.
3.
4.

Answer 6

1. composition of parent rock
2. temperature and pressure
3. tectonic forces
4. fluids

Question 7

heat, necessary for metamorphic reactions, comes primarily from __.

Answer 7

geothermal energy

Question 8

Usually, the deeper a rock is beneath the surface, the hotter it will be. The particular temperature for rock at a given depth depends on the ___.

Answer 8

geothermal gradient

Question 9

a mineral is said to be ___ if, given enough time, it doesn’t react with another substance or convert to a new mineral or substance.

Answer 9

stable

Question 10

minerals stable at higher temperatures are ___ because it allows greater vibration of atoms

Answer 10

less dense

Question 11

the rate at which temperature increases with increasing depth beneath the surface

Answer 11

geothermal gradient

Question 12

the pressure gradient (increase in lithostatic pressure with depth) is approximately ___.

Answer 12

1 kilobar per each 3.3 kilometers of burial in crustal rock.

Question 13

pressure applied equally on all surfaces

Answer 13

confining pressure or lithostatic pressure

Question 14

minerals formed under high-pressure conditions tend to occupy ___ than its polymorphs.

Answer 14

less space

Question 15

if both temperature and pressure increase, then whichever is ___ will have its effects shown on the rock.

Answer 15

greater than the other (e.g. more pressure than temperature)

Question 16

force applied on a rock that is strong in some directions and weak in others is called ___

Answer 16

differential stress

Question 17

the type of metamorphism which occurs from shearing

Answer 17

dynamic metamorphism

Question 18

differential stress that squeezes a rock as shown here is termed ___.

Answer 18

compressive stress

Question 19

where is water for metamorphosis found?

Answer 19

it can be found in fractures, hydrated minerals such as clay and mica, and pore spaces.

Question 20

When a rock has a planar texture, it is said to be ___.

Answer 20

foliated

Question 21

the process in which a platy material like clay or mica undergoes differential stress and grows parallel to the direction of sheering

Answer 21

foliation

Question 22

variations of foliation
1.
2.
3.

Answer 22

1. slaty
2. schistose
3. gneissic

Question 23

If the rock splits easily along nearly flat and parallel planes, we say the rock is ___

Answer 23

slaty or possesses slaty cleavage

Question 24

Rocks that split into thin slabs when hit with a hammer exhibit rock cleavage.

rock cleavage is best displayed in slates that exhibit an excellent splitting property called ___.

Answer 24

slaty cleavage

Question 25

If visible materials have grown parallel to a plane from differential stress, the rock is ___.

Answer 25

schistose

Question 26

if the rock has distinct bands and layers, the rock is ___.

Answer 26

gneissic

Question 27

___ rocks develop in environments where deformation is minimal.

Answer 27

non-foliated

Question 28

these non-foliated rock sometimes contain large grains called ___ which are surrounded by a fine-grained matrix of other minerals.

Answer 28

porphyroblasts

Question 29

Foliated metamorphic rock (listed from low-grade to high-grade)

Answer 29

1. slate
2. phyllite
3. schist
4. gneiss

Question 30

Fine-grained foliated rock composed of minute chlorite and mica flakes

Answer 30

slate

Question 31

___ represents a degree of metamorphism between slate and schist. it is distinguished from slate by its glossy sheen and wavy surface

Answer 31

phyllite

Question 32

Medium- to coarse-grained metamorphic rocks in which platy minerals are dominant

Answer 32

schists

Question 33

nonfoliaited metamorphic rock (list them down)

Answer 33

1. marble
2. quartzite
3. hornfels

Question 34

nonfoliated rock formed through the metamorphism of limestone or dolostone

Answer 34

marble

Question 35

very hard nonfoliated rock formed from quartz sandstone. it can be taxing on construction equipment

Answer 35

quartzite

Question 36

a fine-grained nonfoliated rock with varying mineral composition unlike marble and quartzite.

Answer 36

hornfels

Question 37

When a rock becomes buried to increasingly greater depths, it is subjected to increasingly greater temperatures and pressures and will undergo ___ wherein it recrystallizes into a higher-grade rock.

Answer 37

prograde metamorphism

Question 38

also known as thermal metamorphism, this type of metamorphism is one in which high temperature is the dominant factor.

the parent rock is baked into a metamorphic rock.

Answer 38

contact metamorphism

Question 39

zone of contact metamorphism

Answer 39

aureole

Question 40

the type of metamorphism typically associated with mountain building, where large segments of Earth’s crust are intensely deformed by the collision of two continental crust blocks.

Answer 40

regional metamorphism

Question 41

When hot, ion-rich water circulates through pore spaces or fractures in rock, a chemical alteration called ___ may occur.

Answer 41

hydrothermal metamorphism

Question 42

explain the hydrothermal processes and water’s role in them.

1. during metamorphism…
2. during metasomatism…
3. when hydrothermal rock…

Answer 42

during metamorphism, water transports ions between grains in a rock and/or incorporated into crystal structures.

during metasomatism, water brings ions from outside the rock and are added to the rock during metamorphism.

when hydrothermal rock crystallize in a fracture to form a vein, water passes through the cracks in rock and precipitates minerals on the walls of cracks and pore spaces.

Question 43

mineral formed when oxygen in the atmosphere bonds with iron to form iron oxide

Answer 43

hematite