Brainscape's Knowledge GenomeTM

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


See full index

GLE 2024 (Day 2) > METAMORPHIC PETROLOGY (METAMORPHISM TYPES) > Flashcards

METAMORPHIC PETROLOGY (METAMORPHISM TYPES) Flashcards

1
Q

Differentiate local and regional met based on scale

A

local met : < 100 sqkm
Regional met : > 100 sq km

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

Tectonic or geologic settinsg where local met occurs?

A

1)Impact craters (Impact Met)
2) Fault and Shear Zones (Dynamic Met) and
3) Igneous contact with country rocks (Contact Met)

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

Tectonic or geologc setttings where regional met occurs?

A

Covergent or divrgent plate boundaries

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

What is impact metamorphism?

A

Metamorphism which occurs via explosive volcanic eruptions or relatively rare collisions of extraterrestrial objects wiith earth

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

What are the products of high strain rate w/in impact met?

A

Breccias,
shocked quartz lamellae,
pseudotachylites

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

Ultrahigh pressure silica polymorphs?

A

Coesite and Stishovite

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

Rocks produced by meteorite impacts?

A

Impactites

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

The age which is said to be dominated by meteorite bombardement

A

4.3 Ga (Pliocene)

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

A meteorite impact crater under the Yucatan Peninsula in Mexico which is said to be responsible for the extinction of dinosaurs

A

Chicxulub crater (65Ma)

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

impact crater located in arizona desert of SW USA which was tought to be a volcanic crater and is the site where astronauts trained for their moon walk in the 1960s

A

Meteor Crater/ Barringer Crater (25K-50K years)

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

A layered intrusive igneous complex recognizes to be a meteorite impact structuer

A

Subdury Complex (1.85 Ga)

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

What is dynamic metamorphism?

A

Metamorphism induce by non uniform stress in fault zones and shear zones which is usually of local extent but can also occur in regional scale in areas of large fault or shear zones

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

Rocks which are fragmented angular with finer grained matrix formed by dynamic metamorphism at depths of 5km of the upper crust in which there is relatively cold rocks low earth pressure

A

Cataclasites

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

This is a type of cataclasite with coarser clasts (>2mm) making up at least 30% of the rock

A

Fault Breccia

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

Another term for fault breccia

A

Melange

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

cataclasite with matrix <50% of the rock vol

A

PROTOcataclasite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

cataclasite with matrix 50-90% of the rock vol

A

MESOcataclasite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

cataclasite with matriz >90% of the rock vol

A

ULTRAcataclasite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

These are partially melted rocks formed by quenching under high strain rates in shear zone fractures w/in 5-10 km depth. These rocks are characterized by ultrafine-grained vitreous material usually black or flinty that occurs in dilation fractures of the host rocks in the form of planar veins, injection veins or matrix

A

Pseudotachylites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What drives partial melting to form pseudotachlites?

A

Frictional Heat and geothermal gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

These are rocks fromed by grain size reduction via microscopic cataclasis, plastic stretching and thinning associated with narrrow ductile shear zones at depths greater than 10-15 km

A

Mylonites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

These are rocks associated with wide ductile shear zones

A

Striped Gneiss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

These are local metamorphism which develop where hot magmas intrudes relatively colder upper crustal country rocks at depths less than 10km. (Variable temp and low P)

A

Contact Metamorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What dictates temperature in contact met zones?

A

Size, temp of pluston and distance from the intrusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

This is produced by the heat around an igneous intrusion which ranges from cm to hundred of meters in diamter chracterized by difference in mineral assemblages caused by alteration

A

Metamorphic aureole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

A general term for fine-grain, contact metemorphic rock rich in silcates

A

Hornfels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

protolith of hornfels

A

Mudstones

28
Q

These rocks are formed by contact metemophism of quartz arenite

A

Metaquartzites

29
Q

This develop when igneous rocks intrude carbonate rocks

A

Skarns

30
Q

How do skarns form?

A

When chemical reactions with magmatic fluids result in enrichment of carbonate rocks with SiO2

31
Q

This type of met. is associaed with hydrothermal altertaion at oceanic spreading ridges.

A

Ocean floor metamorphism

32
Q

How does extensional fractures and normal faults serve as two way conduits?

A

It serves as vents for hot magma which result in extensive metal sulfide deposits in basic ign rocks at the same time, cold oygenated seawater descends through fissures and reacts with the basaltic crust enriching it in Na and Mg.

33
Q

IN which environments will Oli and pyx alter to magnetite and hematite?

A

Shallow oxidizing envi

34
Q

What variety of olivine and pyx alter to serpentinite?

A

Mg-rich varieties (Forsterite and Enstatite)

35
Q

How does spilitization occur?

A

Exchange of Na from Sewater and Ca from ca-plag in basalts result in conversion to na-plag such as albite

36
Q

Na-rich basalt

A

Spilites

37
Q

Where does spilite usually form?

A

Oceanic ridges and volcanic arcs

38
Q

where does it occur in the surface?

A

Precambrian greenstone belts and ophiolites

39
Q

minerals associated with spilitic basalt

A

Chlorite, Epidote, Actinolite (Propylitic Minerals)

40
Q

This results from increase in lithostatic stress induced by deep burial of rock and produces non-foliated textures which usually affects regional subsiding basins that accumulate sequences of sediments and volcanic debris (low grade Met via increase in T and P)

A

Burial Met

41
Q

Tectonic settings in which burial met can occur?

A

Rifts,
Foreland Basins,
Passive Marine Basins,
Contental margings,
Forearc and Backarc basins and
pull apart basins

42
Q

Temperature ranges of burial met

A

150-350 deg cel

43
Q

Low temp mineral assemblages of burial met

A

Zeolite,
Prehnite,
Pumpellyite,
Chlorite and
Micas

44
Q

Modern day example of burial met?

A

Bay of Bengal and
Gulf of Mexico

45
Q

A regional met induced by varying increase both in pressure via non-uniform stress and temp which usually produced foliated rocks and is the most aerially extensive met type on Earth

A

Dynamothermal Met

46
Q

Where does dynamothermal met dominate?

A

Covergents margins associated with fold and thrust felds

47
Q

These are the most volumetrically and economically important types of met?

A

Ocean Floor and Dynamothermals

48
Q

Results when heat transfer is dominant agent especially near pluton?

A

Thermal Met

49
Q

Occurs when stress results to deformation and recyrstallization

A

Dynamic Met

50
Q

Results when both temp and stresses are combined

A

Dynamothermal

51
Q

Results when fluid enhanced infiltration and alteratiion

A

Metasomatism

52
Q

Regional vs local

A

regional
? area of wide extent
? affecting large volume of rock
? large scale tectonic processes (Seafloor spreading, crustal thickening, and deep basin subsidence) while

local are those with
?limited volume extent (Magmatic intrusion, faulting or meteorite impact)

53
Q

Met types falling under regional classification?

A

Orogenic and Burial

54
Q

Diff orogenic and burial

A

Orogenic is associated with various phase of mountain building including both compressional and extensional regimes while

burial is a lowgrade met in sed basins due to burial

55
Q

Met types falling under Regional-Local Classificaion?

A

Ocean-Floor and hydrothermal Met

56
Q

What is ocean floor met?

A

related to steep geothermal gradient occuring near spreading centers what causes incomplete recrystallization assoc with cicrulaiong hot aqeous fluid

57
Q

What is hydrothermal met?

A

Met associated with hot H2O rich fluids

58
Q

What are met types under local met? (6)

A

1) Contact,
2) Dislocation,
3) Impact,
4) hot Slabs,
5) Combustion and
6) Lightning met

59
Q

Met occuring adjacent to ign intrusions as a result of thermal and metasomatic effects of mgma

A

Contact Met

60
Q

Met rocks from in the surroundng country rocks

A

Contact aureole - Ito mismo ung met rocks

61
Q

Assoc with fault or shear zones inducing grain reduction in rocks

A

Dislocation Met

62
Q

Caused by passage of shock waves due to impact of extraterrestrial body which involves melting and vaporiztaion

A

Impact Met

63
Q

This met occurs beneath an emplaced hot tectonic body where thermal gradient is steep and inverted

A

Hot Slab Met

64
Q

Metamorphism cause by spontaneous combustion of naturally occuring substances such as bituminous rock, coal or oil

A

Combustion Met

65
Q

Met due to strlke of lightning which produces rocks that are almost entirely glass

A

Lighting met

66
Q

Rocks that is produced from lightnin strike

A

Fulgurite

GLE 2024 (Day 2) (41 decks)

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