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GLE 2024 (Day 2) > IGNEOUS PETROLOGY (IGNEOUS ROCK ASSOCIATION) > Flashcards

IGNEOUS PETROLOGY (IGNEOUS ROCK ASSOCIATION) Flashcards

1
Q

Associations of rocks that form in response to similar geologic conditions

A

Petrotectonic Assoaciations

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2
Q

How much of Earth’s magma is generated in each plate boundaries

A

Divergent 62%
Convergent 26%
Hotspot 12%

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3
Q

Layer 1

A

Well Stratified Pelagic Sediments that accumulated on the ocean floor

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4
Q

Layer 2

A

Pillow Basalts
Sheeted Diabase Dikes

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5
Q

Layer 3

A

Massive Isotropic Gabbro
Layered Cumulate Gabbro
Layered Cumulate Peridotite

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6
Q

Layer 4

A

Depleted Mantle Peridotite (Harzburgite, Dunite)

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7
Q

What marks the Seismic moho?

A

between Cumulate Gabbro and Cumulate Peridotite
Based on seismic wave evidences

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8
Q

most abundant volcanic rock on Earth

A

Mid Oceanic Ridge Basalts

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9
Q

MORB that is strongly depleted with incompatible elements
and represents partial melting at 20-30% of depleted mantle source

A

Normal MORB (N-MORB)

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10
Q

MORB that is enriched with incompatible elements
With smaller degrees of Partial Melting

A

Enriched MORB (E-MORB)

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11
Q

Compare the Andesite and Rhyolite formed in Oceanic Ridges to those formed in convergent boundaries

A

?Hgiher TiO2
?Always subordinate to Basalt

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12
Q

Factors that affects magma composition in Convergent Plate Boundaries

A

1) Composition and Thickness of Overlying Plate
Thin Ocean - Metaluminous
Thick Continental - Peraluminous
2) Composition of Rock Material being Melted
3) Flux Melting
4) Other Diversification Processes
5) Dip Angle of Subduction Zones
Cold Old Dense Lithosphere - Shallow Subduction
Young Warm Bouyant - Steeply Inclined Subduction zones

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13
Q

Dominant Igneous Rocks Found in Convergent Plate Boundaries

A

Calc-Alkaline
Enriched in SiO2, K2O, Na2O, LIL, LREE (Incompatible)

Depleted in FeO, MgO, HFS and HREEs

> 3% Water (Hblde and Biotite)

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14
Q

Calc Alkaline association that is the signature volcanic rock suite of convergent boundaries

A

BADR (Basalt, Andesite, Dacite, Rhyolite)

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15
Q

Volcanic Rocks w/ 45-52% SiO2

A

Basalt

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16
Q

Type of Basalt found in Convergent Boundaries that have higher Al2O3 content but are also enriched in Fe and low K2O

A

Arc tholeiites/High Aluminum Basalt

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17
Q

Basalts found in convergent boundaries with higher alkali content K2O and do not have Iron Enrichment

A

Calc Alkaline Basalt

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18
Q

Type of Andesites with 52-57% SiO2 and are found in Youthful Island Arc Systems

A

Basaltic Andesites

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19
Q

Types of Andesites with 57-63% SiO2 and are found in more mature continental Arcs

A

Silicic Andesite

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20
Q

What are the phenocrysts which may occur in Porhyritic Andesite

A

1) Plag (Euhedral and Zoned)
2) Hbld (Reactions Rims)
3) Pyroxene
4) Biotite

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21
Q

Angle of subduction which favor generation of volumnous andesite

A

> 25 deg

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22
Q

Quartz-phyric vlcanic rocks intermediate between andesite and rhyolite with 63-68% extending to 77% TAS Classification and are enricehed in palagicolases and Minor kfelds

A

Dacite

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23
Q

Rocks composed of 66-69% SiO2 with limit at 57% SiO2 in TAS and commonly contain phenocrysts of ANDESINE to OLIGOCLASE amids a goundmass of ORTHOCLASE and AUGITE high K2O

A

Trachyandesite (Shoshonite and Latites)

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24
Q

Volcanic Rocks with >69% SiO2 associated with explosve silicic eruptions

A

Rhyolites

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25
Q

Volcanic Rocks with 68-73% SiO2 which can occur as glasses, pyroclastc tuffs and breccias

A

Rhyodacite(unofficial)

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26
Q

Rocks which dominates if the overlying slab thickness rangers from 0-20 km thin

A

Low K Tholeiites/Arc Basalts

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27
Q

Rocks which Dominates if the overlying slab thickness ranges from 20-40km moderate

A

Mod K Calc Alkaline Andesite

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28
Q

Rocks which Dominates if the overlyin slab thickness is greater than 40 (40Km) Thicker

A

High K shoshonites

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29
Q

Thickness and K-content

A

Thicker the overlying Slab the higher the K-content

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30
Q

Arrange representative rocks in increasing k-content

A

Arc Tholeiites
Calc Alkaline Andesite
Shoshonite

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31
Q

Three types of Convergent Margins with corresponding resultant tectonic landform

A

1) Ocean-Ocean - Youthful Island Arc
2) Ocean-Continental - Mature Continental Complexes
3) Cont-Cont Cessation of Subduction and Collision

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32
Q

Composition of Diorite

A

Plag, Hbld, <5%qtz

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33
Q

Composition of Qtz Diorite

A

Plag, Hbld, 5-20% qtz

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34
Q

Plutonic Equivalents of Rhodacites and dacites

A

Granodiorite (>20% Quartz)

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35
Q

Plutonic Rocks nriched in CALCIC PLAG and QTZ w/ minor Kfelds, Biotite and Hbld

A

Tonalite

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36
Q

Granodioritic rocks in which half to 2/3 of plag are SODIC PLAGIOCLASE

A

Trondhjehmites

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37
Q

IN which part of the volcanic arc are Low K Arc Tholeiites formed?

A

Oceanward nearest to the trench

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38
Q

High Magnesium intermediate Volcanic Rocks that contain SiO2 Saturated Groundmass

A

Boninites

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39
Q

Silica Saturated rocks known to be derived from the the melting of subducting Slab of the oceanic Lithosphere

A

Adakite

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40
Q

Relatively thin Lithosphere in Youthful volcanic arcs will form

A

Basalt
Basaltic Andesites
Boninite
Adakite

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41
Q

Tholeiitic basalts that are more enriched in H2O, alkali Elements and LIL and are slighlty depleted in Ti, Y and Nb

A

Back Arc Basin Basalts (BAB)

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42
Q

Difference of Mature to Youthful island arc?

A

More Enriched in K2O and SiO2 due to thick overlying wedge

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43
Q

What types of plutons occur in Ocean-Continent Subduction?

A

Silicic (Granodiorite, Diorite, and Tonalite)

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44
Q

Volcanic Rocks in Ocean-continent subduction

A

Andesitic, Dacites, Rhyodacites, Rhyolties and Latites

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45
Q

Volcanic Rock that is darkcolored, K-rich trachandesite commonly containing olivine and augite phenocryst with labradorite plag, Kffelds, olviing, augite and leucite ground mass

occrus in thick oceanic crust

A

Shoshonite

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46
Q

Type of granitic magma formed by partial melting of basic to intermediate igneous rocks in or above the subduction zone at ocean-ocean or ocean conv margins and are Mataluminous

A

I-type

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47
Q

Type of granitic magma which are peraluminous mostly found in continent-continent collisions an is dervied from phyllosilicate minerals in sed rocks such as graywackes and mudstone of the concrust and accretioary wedge

A

S-type

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48
Q

Granites derived from mantle derived parental magmas and are associated with calc-alkaline tonalites, Qtz Diorite and Gabbroic Rocks and are developed in Island Arc settings

A

M-Type

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49
Q

Mineralization in such type of granites

A

Cu and Au

50
Q

Types of deposits associated with I-type

A

PCDs, Tungsten and Molybdenum

51
Q

Types of deposits associated with S-Type

A

Tin Deposits

52
Q

Anorogenic rocks produced by activties unrelated to subduction and collission and are more enriched in LIL elements and re mostly alkali rich

A

A-Type

53
Q

Fault bounded, deformed rck sequence that mark the site of present or former convergent margins which may have been transprted far from their site of origin by thrust faulting

A

Alpine Orogenic Complexes

54
Q

An intensely Sheared, heterogenous rock assemblage embedded within a highly deformed mud matrix

A

Melanges (Mixture))

55
Q

A type of Alpine deposit in which the oceanic or back arc basin lithospher or volcanic arc basement are preserved in origenic belts which represents coherent slices of oceanic lithsphere, volcanic arc basement or back arc basin ltihosphere obudcted onto the edge of a subduction zones

A

Ophiolites

56
Q

Ophiolites that represent oceanic fragments in either forearc aor back arc settinsg

A

Suprasubduction Zone Ophiolite (SSZ)

57
Q

Consists of concentrically layered zoned plutons formed in convergent margin settings with a dunite core and pyroxenite shell and surrounded by massive gabbro

A

Alaska Type Intrusion

58
Q

Deposits which are related to Alaska Type Intrusion

A

PGEs

59
Q

Refers to magma gneraton and igneous rocks suites produced within lithospheric plate

A

Intraplate Magmatism

60
Q

Greatest maniferstaton of intraplate magmatism encompassing volumes of >1000000 cu.km

A

LIPs (Large Ign Provinces)

61
Q

Yellowstone is what type of LIP?

A

SLIP

62
Q

Volcanic Landforms that rise upward above sea level

A

Ocean Islands

63
Q

Volcanically produced peaks below sea level

A

Seamounts

64
Q

Broad flat topped areas resulting from large outpourings of lava flowing laterally from source vents

A

Oceanic Plateaus

65
Q

Difference of OIB from MORB

A

More alkalic
Enriched in Incompatible elements

66
Q

MORB: Partial Melts of upper Depleted Mantle
OIB:

A

Partial Melts of a depper, Encriched Mantle-like Source which is non primitvive (Subducting Slab + Mantle Peridotite)

67
Q

Dominant Rocks in Hawaii

A

Olvine Tholeiites

68
Q

Trend of Magma Composition in Hawaii

A

Early Alkali Basalts
Tholeiitic Basalts generating Shield Volcanoes
Late Stage Alkali Volcanism (Hawaiiates and Benmoreites)

69
Q

Alkalic Magma indicates

A

Low Degrees of Melting as island move away from the hotspot source

70
Q

Fractionaton Sequence occuring at Ocean Islands

A

Basalts
Hawaiiite
Mugearites
Benmoreites
Trachytes - Saturated
Phonolite - Undersaturate
Rhyolite -Supersaturated

71
Q

Largest oceanic Flood Basalt on earth which encompasses a surface area of 2,000,000 sq. km2 and a volume of 60 million cu.km

A

Ontong-Java Plateau

72
Q

Age of Ontong Java Plateau

A

122 Ma (E.Cret)

73
Q

Basalts of Ontong Java Plateau

A

Low K-Tholeiitic Basalt

74
Q

Products of Continental Intraplate magmatsm and volcanism

A

1) CFBs
2) Continental Rifts
3) Bimodal Volcanism
4) Layered Basic and Ultrabasic Intrusions
5) Utlrabasic suites (Komatiites and Kimberlites)
6) Unusual Array of Alkaline Rocks and Anorogenic Granites

75
Q

Three largest Bsalt Events which all corresponds to Largest extinction event on Earth

A

1) Permo-Triassic Siberian Traps
2) Triassic-E.Jurassic CAMP Central Atlantic Magmatic Province
3) Cret-Tertiary Deccan Traps

76
Q

What does SLIP stands for?

A

Silicic Large Igneous Provinces

77
Q

CFB which formed during the break up of Pangaea which produced rift basins and flood basalt in N and S America, Europe and Africa

A

Central Atlantic Magmatic Province

78
Q

Rock composition of CAMPS

A

Tholeiitic (Low TiO2) and Andesitic

79
Q

Size of Camp

A

7 Million Sq.Km

80
Q

Siberian Flood Basalts is mostly

A

Tholeiitic w/ minor trachyandesites, nephelinites, picrites, volcanic agglomerates an tuffs

81
Q

Area of Siberian Traps

A

3.9 Million sq. Km

82
Q

Flood Basalt in Western India

A

Deccan Traps

83
Q

Area of Deccan Traps

A

1 Million Sq, km

84
Q

Basalts of Deccan Traps

A

Tholeiitic w/ minor Alkalic Basalts orignated by fractional crystallization of shallow magma chambers

85
Q

Continental Rifts Rocks

A

?Alkalic Basalt
?Alkaline Rocks
?Silicic Rocks

86
Q

Known Continental Rifts

A

?East African Rift Basin - Alk. Basalt + Phonolite Trachyte and Carbonatite
?Lake Baikal - Russia
?Basin and Range - USA
?Rio Grande Rift System - USA

87
Q

Widespread occurrence of Basalt and Rhylolite without Andesite

A

Bimodal Volcanism

88
Q

Source of Layered Mafic Intrusions

A

Differentiation of Eclogite-Peridotite Parent Magmas resulting in mineral segregation within the pluton

89
Q

Largest LMIs

A

Stillwater in Montana, USA
Bushveld in S.Africa
Skaergaard in Green Land

90
Q

Oldest Known LMI

A

Stillwater Complex Montana

91
Q

Age of Stillwater Complex

A

2.7 Ga NeoArchean

92
Q

What are the zones of Stillwater complex?

A

1) Upper Banded Zone - PGEs, Cu, Ni
2) Ultramafic Zone - Cu, Cr, Ni-Sulfides
3) Basal Zone - Cu, Cr, Ni-Suflides

93
Q

Largest LMI in the world

A

Bushveld Complx

94
Q

Age of Bushdveld Complx

A

2.06 Ga Paleoproterozoic

95
Q

Layers of Bushveld Complex that contains deposits

A

1) Granite Capping - Sn, F, Mo
2) Critical Zone - PGE
3) Basal Zone Upper Chromite Horizon - Chromium

96
Q

Host of Largest PGE Deposit

A

Merensky Reef

97
Q

Host of Chromite

A

UG2 Reef7

98
Q

What type of intrusion is the Bushveld Complex?

A

Laccolith saucer type

99
Q

The youngest Great Pge enriched intrusions

A

Skaergaard Intrusion, Greenland

100
Q

Age of Skaergaard

A

55 Ma (Late Paleocene)

101
Q

Ultrabasic Volcanic Rocks found exclusively in Archean Greenstone belts characterized by high Mg content (>18%), olivine rich and depleted in Titanium and LREE

A

Komatiites

102
Q

Metamorhosed assemblages of green-colored rocks containing layers of Ultrabasic and basic rocks overlain by silicic rocks and sediments

A

Greenstone Belts

103
Q

Where and when was komatiites flow first recognized?

A

1969, Barberton S.Africa

104
Q

Consist of Needle-like, acicular olivine, Pyx, and chromite phenocrysts in glass groundmass

A

Spinifex textute

105
Q

Why is there no Phanerozoic Komatiite?

A

Due to lower upper Mantle temperature which precludes the extensive mantle melting required to produce komatitic melts

106
Q

Temperatures at which komatiites form

A

1575-1800 deg cel

107
Q

The only known Phanerozoic Kimatiitie

A

Gorgona Is. Colombia (88 Ma)

108
Q

Example of Greenstone Belts thath contain Komatiitie

A

Yilgarn Craton (2.7 Ga)
Barberton (3.5 Ga)
Canadian Shield (2.7 Ga)

109
Q

Brecciated, Mg-rich Ultrabasic Rocks that rapidly rise to Earth via cylindrica Diatremes from deep within the mantle

A

Kimberlites

110
Q

Temperatures at which kimberlite originates

A

1200-1400 deg cel (>150km)

111
Q

What forms from Kimberlite eruptions?

A

Diatreme Maar

112
Q

Major Mineral in Kimberlite?

A

Olivine

113
Q

Aside from Diamond what other high pressure minerals exist in Kimberlites?

A

Pyrope Garnet
Jadeite Pyroxene

114
Q

SiO2 Undersaturated Hypabyssal Rocks

A

1) Carbonatite
2) Lampropyres
3) Lamproites

115
Q

Shallow/Hypabyssal intrusive to volcanic rocks containining >20% CO3 minerals such as Natrolite, trona, Sodic calcite, Magnesite, and Ankerite

A

Cabronatite

116
Q

Magnesium rich volatile rich porphyriticl rocks containing mafic phenocrysts susch as Biotite, Phologopite, Amphibole, Cpx and Melilite
Usually associated with kimberlites and continental rift zones

A

Lamprophyres

117
Q

K-rich, peralkaline rocks containing leucite, sanidine, phlogopite, richterite, diopside and livine and are enriched in barium, lanthanum, zirconium but are relatively poor in CO2 and occurs in areas of thickened lithosphere

A

Lamproites

118
Q

Silicic plutonic rocks unrealted with convergent margin tectonism and occurs in stable cratons and other passive areas.

A

Anorogenic Granites (A-types)

119
Q

what is the distinctive age of A-type granites?

A

Mid Proterozoic

120
Q

Distinctive texture of Atype granites which refers to Na-Plag overgrowths on preexisting orthoclase crystals (Unlike Perthitic which is formed due to exsolution)

Rims of Oligoclase around alkali feldspar megacrysts

A

Rapakivi Texture

GLE 2024 (Day 2) (41 decks)

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