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Geology Board Exam Day 2 > Igneous Petrology > Flashcards

Igneous Petrology Flashcards

1
Q

The science concerned with rocks, including their mode of occurrence, composition, classification, origin, and their relations to geological processes and history.

A

Petrology

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2
Q

A branch of petrology that deals with the history and origin of the rock; interpretations of the origin of rocks

A

Petrogenesis

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3
Q

places emphasis on the purely descriptive part of rock science from textural, mineralogical, and chemical points of view.

A

Petrography

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4
Q

Study of description and classification of rocks. It is considered an observational science because it looks at the physical features such as color, mineralogy, texture, etc.

A

Petrography

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5
Q

the branch of geology dealing with the origin, occurrence,
structure, and history of rocks.

A

Petrology

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6
Q

Rocks that directly solidify from molten or partially molten material, i.e. magma.

A

Igneous Rocks

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7
Q

two basic types of igneous rocks

A

intrusive igneous rocks and extrusive igneous rocks

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8
Q

what is the difference between intrusive igneous rocks and extrusive igneous rocks?

A

intrusive igneous rocks are formed beneath the surface of the Earth

extrusive igneous rocks are formed at the surface of the earth.

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9
Q

another term for extrusive igneous rocks

A

Volcanic rocks

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10
Q

another term for intrusive igneous rocks

A

Plutonic Rocks

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11
Q

three general types of magma based on their chemical composition

A

Basaltic magma
Andesitic magma
Rhyolitic magma

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12
Q

Magma that has 45-55% SiO2, high in Fe, Mg, Ca; low in K, Na; and has temperature range of 1000-1200°C

A

Basaltic Magma

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13
Q

Magma that has: 55-65% SiO2, intermediate in Fe, Mg, Ca, K, and Na; has a temperature range of 800-1000°C

A

Andesitic Magma

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14
Q

Magma that has 65-75% SiO2, low in Fe, Mg, Ca; high in K, Na; and has a temperature range of 650-800°C.

A

Rhyolitic Magma

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15
Q

Low viscosity, low gas content, high-temperature magma

A

Basaltic Magma

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16
Q

intermediate viscosity, intermediate gas content, intermediate temperature magma

A

Andesitic Magma

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17
Q

High viscosity, High gas content, Low-temperature magma

A

Rhyolitic Magma

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18
Q

Magma is generated for? and with what process?

A

Mantle; through Partial Melting

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19
Q

Heat sources on the Earth

A
  1. Heat from the early accretion and differentiation of the Earth;
  2. Heat released by the radioactive breakdown of unstable nuclides
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20
Q

similar to the melting of dry minerals, melting temperatures increase with increasing pressure, except there is a range of temperature over which there exists a partial melt, Partial melting can range from 0 to 100%

A

Melting of dry rocks

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21
Q

similar to the melting of wet minerals, melting temperatures initially decrease with increasing pressure, except there is a range of temperatures over which there exists a partial melt

A

Melting of rocks containing water or carbon dioxide

22
Q

What are the ways to generate magma on (solid part of) the earth?

A

increase/ raise the geothermal gradient
lower the melting temperature of rocks.

23
Q

3 mechanisms of Magmatic Differentiation.

A

Fractional Crystallization
Magma mixing
Magmatic assimilation

24
Q

Likely to be the most important in controlling magmatic differentiation.

A

Crystal fractionation

25
Q

Magma is close to its original composition and has therefore in theory not undergone crystal fractionation.

A

primitive magma

26
Q

Magma in which crystal fractionation has taken place such the magma composition is different from the starting composition.

A

Evolved Magma

27
Q

where two magmas with different compositions happen to come in contact with one another and mix together and have a composition somewhere between that of the original two magma compositions.

A

Magmatic Mixing

28
Q

magma reacts with the “country rock” which is adjacent to the magma chamber.

A

Assimilation

29
Q

incompletely melted chunks of country rock. these materials contaminate the magma by incorporating materials originally present in the country rock.

A

Inclusions

30
Q

The reaction between the magma and the wall rock/ host rock

A

Magmatic assimilation

31
Q

Minerals in Bowen’s reaction series: Discontinuous series (in order from high to low temp, and increasing SiO2 Liquids)

A

Olivine, Pyroxene, Hornblende (amphibole), Biotite

32
Q

Minerals in Bowen’s reaction series: continuous series (in order from high to low temp, and increasing SiO2 Liquids)

A

Ca-rich to Na-rich Plagioclase (ABLAOA)

33
Q

Refers to any process that cause magma composition to change.

A

Magmatic Differentiation

34
Q

the proposed processes of Magmatic Differentiation

A
  1. Distinct melting events from distinct sources
  2. Various degrees of partial melting from the same source
  3. Crystal Fractionation / Fractional Crystallization
  4. Mixing of 2 or more magma (Magma mixing)
  5. Assimilation/ Contamination of magma by crustal rocks
  6. Liquid Immiscibility
35
Q

Each magma might represent melting at a different
source rock at different times during the heating event

A

Distinct melting events from distinct
sources

36
Q

In multicomponent rock systems, each component has its own melting range temperature.

A

Various degrees of partial melting from
the same source

37
Q

the liquid composition changes as a result of removing crystals from the liquid as they form creating a magma with a different composition from the parent magma

A

Crystal Fractionation / Fractional Crystallization

38
Q

2 mechanism of fractional crystallization

A

Crystal settling/ floating crystals
Inward crystallization

39
Q

Forming from magma will have different densities; Higher-density crystal sinks and lower-density crystal floats.

A

Crystal settling/ Floating Crystals

40
Q

The magma body is hot and the country rock that surrounds it is expected to be cooler, heat will move outward, away from the magma; the walls of the magma body will be coolest, crystallization is expected to take place in the cooler portion; magma expected to
crystallize from walls inward

A

Inward crystallization

41
Q

Two or more magma with different compositions come in contact with one another beneath the surface and mix to produce magma with a composition intermediate between the end member (the two magma).

A

Magma Mixing

42
Q

factors that can inhibit (hinder) mixing.

A

Temperature contrast
Density contrast
Viscosity contrast

43
Q

The mechanism that makes magma mixing possible

A

Stirring e.g. Convection
(where hotter magma rising through the cooler magma)

44
Q

Evidence(s) of Mixing

A

Mingling of Magmas
Disequilibrium mineral assemblages
Reverse Zoning
Glass Inclusions
Chemical Evidences

45
Q

“marble cake” appearance, dark-colored mafic rock intermingled with lighter-colored rhyolitic rock (banding)

A

Mingling of magma

46
Q

basaltic magma containing Mg-rich olivine mixed
with rhyolite magma containing quartz

A

Disequilibrium mineral assemblages

47
Q

minerals placed in an environment different than the one in which it originally formed, will react, instead of dissolving completely, solid solution minerals start precipitating new composition that is stable – zoned crystals

A

Reverse Zoning in Minerals

48
Q

Crystal grows trapping liquid inside; glass should represent the composition of magma that precipitated the crystal.

A

Glass inclusions

49
Q

oxide-oxide variation diagrams

A

Chemical evidence

50
Q

A state in which two liquids with different compositions coexist in equilibrium with each other.

A

Liquid Immiscibility

51
Q

___________ do not mix and form an emulsion of droplets or network of one liquid within the other

A

Immiscible

Geology Board Exam Day 2 (17 decks)

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