Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Interior Geology > Metamorphism 9-11 > Flashcards

Metamorphism 9-11 Flashcards

1
Q

Metamorphism

A

Recrystallisation without melting under heat and/or pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Thermal or Contact metamorphism

A
  • High-temperature low pressure

- Rocks near an igneous intrusion will be heated and recrystallized; metamorphic ‘aureole’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Metastability

A

Rocks brought out of their regions of stability where they are formed take a long time to break down as will not have the activation energy to recrystallize

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Regional metamorphism

A

Metamorphism formed due to conditions in a region under the earth
Burial at depths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Low-temperature high-pressure metamorphism

A

Formed in subduction when the rock does not have time to heat up but is exposed to great pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Paired metamorphic belts

A

Igneous intrusions above subduction zones and belts formed by high pressure subduction often come together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Facies

A

Formed under identical conditions with different minerals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Idioblastic (or Idiomorphic)

A

Crystals completely bounded by their own crystal faces; the metamorphic equivalent of euhedral.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Metapsammitic

A

Describes rocks formed by the metamorphism of sandstones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Dynamic metamorphism

A

Dominant processes involve deformation and recrystallisation rather than temperature change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Migmatitic

A

Partly metamorphic and partly igneous in appearance, commonly formed by partial melting in metamorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Metasomatic

A

Describes a metamorphic process involving mass transfer and change of bulk chemical composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Protolith

A

Original rock changed by metamorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Lithostatic load

A

Pressure on rocks caused by the weight of rocks above it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

3 agents of metamorphism

A

Temperature
Pressure
Fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cataclasitic

A

Rock ground and crushed during faulting

17
Q

Prograde vs Retrograde

A

Prograde metamorphism is when minerals adapt to more extreme conditions
Retrograde metamorphism is when minerals adapt to less extreme conditions

18
Q

Isochemical metamorphism

A

New minerals are formed from others without large-scale migration of chemicals

19
Q

Recrystalisation of strained minerals

A

Same mineral recrystallises in a different way to allow it to unstrain e.g. quartz

20
Q

Formation of new textures / Foliation

A

Minerals are realligned in response to deformarion and form in a pattern

21
Q

Low grade Regional Metamorphism

A

Rock types: Slate
Temperatures: 200-350
Pressures: 2-3 kbar (6-10km)
Index minerals: Muscovite, Chlorite (250-325), Biotite (325-375)

22
Q

Medium grade Regional Metamorphism

A

Rock types: Schist
Temperatures: 350-550
Pressures: 3-4 kbar (10-15km)
Index minerals: Garnet (425-550), Staurolite (525-600)

23
Q

High grade Regional Metamorphism

A

Rock types: Gneiss
Temperatures: >550
Pressures: >4kbar (>15km)
Index minerals: Sillimanite (>550), Kyanite (>4kbar)

24
Q

Pellitic Protolith

A

Protolith fine grained sedimentary rock e.g. mudstone

25
Q

Garnet colour for composition in metamorphism

A

Red - Almandine IRON
Dark - Pyrope MAGNESIUM
Green - Grossular CALCIUM-ALUMINUM

26
Q

Change in texture through regional metamorphic grade

A

Slatey: strong cleavage and foliation
Schistosity: prominant foliations and banding with minerals visible to the naked eye
Gneiss: diffuse bands with segraegated different compositions and larger coarse minerals

27
Q

Index minerals

A

Cholrite-Biotite-Garnet-Staurolite-Sillimanite/Kyanite

Staurolite only forms if there is iron!

28
Q

Aluminum Silicates triple point

A

514 C, 4kbars

29
Q

Low temperature low pressure facies

A

Zeolite

30
Q

High temperature low pressure facies (e.g. Contact metamorphism)

A

Hornfels

31
Q

Low temperature High pressure facies (e.g. subduction)

A

Blueschist

32
Q

Very High temperature (some pressure) facies

A

Granulite

33
Q

Very high pressure (some heat) facies

A

Eclogite

34
Q

2 middle facies in order of increasing temperature

A

Greenschist

Amphibolite

35
Q

Quartzite

A

Metamorphosed sandstone

36
Q

Marble

A

Metamorphosed limestone

37
Q

Metamorphic aureole factors:

A

Size of intrusion - will take longer to cool
Magma temperature - hotter magmas (more mafic usually) will affect the area more
Depth of intrusion - shallow intrusions will cause more change as the rocks around will be cool

38
Q

Metamorphic zones in conact metamorphism of pelites

A

1) Inner Hornfels Zone (C) a granoblastic texture completly recrystalised with interlocking quartz, corderite and biotite surrounding the intrusion (A) and the chilled margin (B).
2) Intermediate Porphyroblastic zone (D) Large andalusite porphyroblasts, and cordierite in slate
3) Outer Spotted slate zone (E) Small spots of metamorphic minerals form. This is surrounted by unaffected mudstone (F)

Interior Geology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions