Brainscape's Knowledge GenomeTM

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


See full index

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

IGNEOUS PETROLOGY (ROCK MELTING) Flashcards

1
Q

Partial Melting

A

Anatexis

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

Partial Melting Produces

A

1) Melt with Low Temp constituent
2) Resitite enriched in higher temp refractory elements

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

Heat Source of Earth

A

1) Heat realeased from the early accretion and differetiation
2) Heat generated by radioactive Breakdown of Unstable Nuclides

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

Modes of Heat Transfer

A

1)Radiation - waves
2) Conduction - Direct Contact
3) Convection - Fluid caused by molecular motion

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

?A type of melting in which no other chemical components are neither added or removed from the environment
?Requires continuous contact between the melt and restite
?Over all composition of the system remains the same with evolving compositions of the melt and solids

A

Equilibrium Melting

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

What can cause incomplete equilibrium Melting

A

Large Crystals
High Viscosity
Low ion migration

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

What can be produced by incomplete equilibrium melting?

A

Zoned Crystals

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

Implies that Solids and Melt SEPARATE into isolated fractions that do not continuously react together during the melting process as is for equilibrium melting

A

Fractional Melting (Disequilibrium Melting)

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

With small degrees of partial fractional melting of ferile source rocks , the melt is said to be enriched in

A

Low Temp Constituents

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

High degress of partial melting will

A

Deplete the melt with low temp constituents thus becoming more evolved

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

Factors in Partial Melting

A

1) increase in temp
2) Decompression
3) Induced Volatilization

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

sloping line of increasing temperature with depth

A

Geothermal Gradient

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

Is geothermal gradient uniform vertically or laterally?

A

Neither

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

Geothermal Gradient

A

25 degC/km for the upper 10km

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

Geothermal Gradient in Old Continental Lithosphere

A

5-10 degC/km

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

Geothermal Gradient in hotspots, MOR, Volcanic Arcs?

A

30-50 degC/km

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

Another term for decompression melting?

A

Adiabatic Melting

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

Pressure within that corresponds to 10Km depth

A

3.3 Kbars

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

Explain decompression melting

A

Since melting temperature is proportional to pressue,
Decrease in pressure within lithospheric thinning in externsional environments effectively decrease melting temp of rocks

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

What type of melts are produced by adiabiatic melting of Mantle Peridotites?

A

Basltic Magmas at MORs and Continental Rifts

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

an agent that reduces the melting temperature of a material or substance

A

Flux

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

Why does increase in volatile content induce partial melting?

A

Increase in H2O causes the bonds in silicates to weaken (Network Modifier) thus progressively lowering the melting teperature

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

Other effects of addition of H2O in terms of melting?

A

?Allows rocks to melt over a wide range of temperature regardless of lithostatic pressure
?Melts are less mafic than the source rock due to decreased amounts of FeO and MgO

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

What minerals are dehdyrated that caused the partial melting of the Mantle Wedge through Induced Volatilization

A

Amphibole
Mica
Serpentine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
at what depths would devolatilization of the subducting slab occur?
80-150 km
26
Describe the composition of the Melt/Daughter Magma during anatexis
Eriched in Low Temp Constituents which includes incompatible elements such as the Large Ion Lithophile Elemets (LILEs) SiO2, K2O, Na2O
27
What rocks can form from the crystallization of the daughter magma?
Silicic w/ qtz, kfelds and Na Plag
28
Describe the composition of the Restite or Residual rock durng anatexis
Enriched in High Field strength Elements with CaO and MgO
29
Explain the effect of degrees of partial melting to enrichment
The higher the partial meltig the more the magma will be depleted with incompatible elements. Incompatible elements are only enriched in low degrees of partial melting
30
which of the Rare Earth Elements are incompatible REEs?
Light REEs (La-Sm)
31
HREEs
Eu-Lu
32
Generalized Product of Melting in varying parent rocks
Partial melting will produce a 1 step more silicic melt compare to more basic parent rock
33
Process whereby early formed crystals are segegated from the remaining melt and is a closed system differentiation
Fractional Crystallization
34
Father of Modern Petrology who suggested that fractionation may be accomplished through the relative movement of crystals and liquid
Norman Levi Bowen
35
The rock formation that was used as a model by Bowen to demonstrate crystal fractionation
Palisades Sill
36
A model based on the crystallzation sequence of major igneous minerals
Bowens Reaction Series
37
When Foresterite crystallizes removing MgO in the discontinuous rection what would be produced?
Enstatite
38
A systematic pattern of chemical variation from the periphery of the crystal towards its center recording an incomplete continuous chemical reaction between the crystal and the surrounding melt
Zoned Crystals
39
A display of new mineral along the crystal periphery that surrounds a partially resorbed core composed of a different mineral which indicate Incomplete Discontinuous chemical reactions between the crystal and the surrounding melt
Reaction Rims
40
Models for Fractional Crystallization Process
1) Marginal Accretion 2) Gravitational Separation 3) Convective Flow 4) Filter Pressing
41
When magma chamber loses heat due to convection to adjacent coutry rocks and crystals tend to form on the margin
Marginal Accretion
42
of all the Marginal accretion, which forms first?
Roof Sidewall Floor
43
Pluton margins adjacent to cool country rocks form this fine grained fabric
Chilled Margins
44
This mechanism of fractional crystallization occur when crystals develop have different density than the surrounding magma
Gravitational Separation
45
Occurs when higher density ferromagnesian minerals settle to the base of a magma chamber relative to the lower density of the melt thus forming discrete layers of crytsal mush
Crystal Settling
46
Occyrs when early formed less dense crystals like plagioclase float towards the roof of the chamber effectively seperating them from the remaining melt
Crystal Flotation
47
What impedes Gravitational Separation?
High Viscocity
48
Occurs whereby liquid and crystals are segregated due to Velocity, density, or temperature variations
Convective Flow Segregation
49
In convective flow segregation, how are melt-liquids fractionated?
Magmga should be LOW VISCOUS in order to have variations in convective flow velocity. ?Dense Minerals will tend to accumulate in regions of High Velocity ?light minerals will be concentrated on areas of low velocity
50
How are convective flows in mamba chamber generated?
By Differential heat loss from the peripheries/margins to the center
51
Happens in late stage cooling of the magma chamber where crystals are compacted and rotated while liquids experience expulsion to the countryrocks
Filter Pressing
52
Processes of Fractional Crystalliztaion
1) Marginal Accretion 2) Crystal Settling and flotation 3) Convective Flow Sergregation 4) Filter pressing
53
two processes which can produce two different distinct daughter magmas from one parent magma
1) Differential Diffusion 2) Liquid Immiscibility
54
Explain Differential Diffusion
?Preferential movement of select ions or favored ions wihitn the magma in response to therma, compositional, or density gradients as well as water content ?plays an important role in transport and concetrtaion of metallic ore minerals in plutonic systems
55
A process wherein a parent magma may segragate in two separate daughter magmas of different composition upon cooling
Liquid Immiscibility
56
Common magma immiscible pairs
Granitic-Basaltic Sulfide-rich - Silicate -rich Alkali-rich - Carbonate-rich
57
Open system differentiation processes
1) Assimilation 2) Magma Mingling and Mixing
58
Occurs where the surrounding wall rock is intruded by and reacts chemically with the magma
Assimilation
59
Controls of Assimilation process
Surface area, larger the surface area the more extensive the exchange of chemical components
60
Process of fracturing the surrounding wall rock by forceful injection of magma
Stoping
61
Country rock fragments that is assimilated in the magma
Xenoliths
62
Foreign crystal not generated by crystallization of the surrounding magma
Xenocrysts
63
Injection of magma to the chamber
Magma Replenishment
64
Occurs when two or more dissimilar magmas coexist in a single chamber, displaying contact relations but retaining their distinctive characteritics (Interject but do not combine)
Magma Mingling
65
Evidence of Magma Mingling of felsic and mafic magmas
Marble Cake Appearance
66
Homogenization inhibitor
Temp Contrast Density Contrast Viscosity Contrast
67
This implies interjection of two dissilimar magmas with thorough mixing so that individual magma components are no longer recognizable
Magma Mixing
68
Example of Magma Mixing of felsic and mafic magma
Intermediate Magma
69
What can serve as evidence for magma mixing
Disequilibrium Mineral Assemblage
70
Environments of Magma Mixing
Continental Rifts Convergent Plate Boundaries

GLE 2024 (Day 2) (41 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions