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Flashcards in Geo Unit 2 Deck (110):
1

Igneous rocks make up ___% of the outer 50 Km of Earth

95%

2

Difference between Lava and Magma

Lava is on the surface of the Earth, Magma is plutonic

3

What is Magma?

Molten liquid, crystals, and gas

4

What are the different textures of Igneous Rocks?

Aphanitic, Phaneritic, Porphyritic, and Volcanic Glass

5

Aphanitic Igneous Rocks

very small mineral grains

6

Phaneritic Igneous Rocks

Large, visible mineral grains

7

What is Texture?

The arrangement, size, and shapes of mineral grains

8

What causes Volcanic glass?

VERY rapid cooling

9

Porphyritic Texture?

Large and small mineral crystals/grains

10

How do you determine the origin of Igneous rocks?

Look at the mineral grain sizes

11

What is the basis for NAMING Igneous Rocks?

The Silica Content

12

What are the three composition classifications for Igneous Rocks?

Felsic, Intermediate, and Mafic

13

Felsic Igneous Rocks?

Light color and Silicon-rich

14

Mafic Igneous Rocks?

Dark color and Silica-poor

15

Felsic and Phaneritic?

GRANITE

16

Felsic and Aphanitic?

RHYOLITE

17

Intermediate and Phaneritic?

DIORITE

18

Intermediate and Aphanitic?

ANDESITE

19

Mafic and Phaneritic?

GABBRO

20

Mafic and Aphanitic?

BASALT

21

What things are part of the creation of magma?

Heat, Pressure, and a small amount of Water

22

Why is water part of Magma Creation?

A small amount of water allows rocks to melt more easily

23

What is the melting point of felsic minerals, and when is it reached?

700 degrees Celsius, and reached around the crust/mantle boundary

24

What is decompression melting?

There is too much pressure for the rocks to be molten, so it must be released before they can melt to become magma

25

What is Magma Evolution?

The last minerals to melt are the first ones to crystallize upon cooling

26

What are the last forming minerals in Magma Evolution?

Low temp, stable minerals (vein minerals)

27

What is Magmatic Differentiation?

The process of forming igneous rocks of different compositions from a single original magma as early-forming minerals remove material from the melt and change it's "recipe" over time

28

What are the three processes in Magmatic Differentiation?

Crystal Settling, Assimilation of Country Rock, and Magma Mixing

29

What is Crystal Settling?

Crystals form and sink to the bottom of the Magma Chamber

30

What is the Assimilation of Country Rock?

Host rock breaks off and falls into rising magma in the chamber

31

What is Magma Mixing?

Adjacent magma chambers will merge and MIX

32

How do you get large felsic bodies in the mafic mantle?

Requires PARTIAL MELTING of existing continental crustal rocks to get the silica-rich material concentrated in granites

33

How are Igneous Rock Bodies formed?

Magma rises and forces its way in through the crust because it is hot, less dense, and is helped by gas expansion

34

What are the three types of Igneous Rock Bodies?

Dikes, Sills, and Plutons

35

What are Dikes?

Discordant, Steep and Vertical Igneous Rock Bodies

36

What are Sills?

Concordant (parallel), Horizontal Igneous Rock Bodies

37

How do you differentiate a Sill from a Lava Flow?

Look at the grain size, the burn zones, and a Sill will pick up rock from the top and the bottom

38

What are Plutons?

general intrusive igneous rock bodies

39

What are Stocks?

Plutons <100 square Km

40

What are Batholiths?

Plutons >100 square Km

41

Why is Volcanism common near ancient civilizations?

Volcanism provides many essentials/benefits

42

What are the benefits that volcanism supplies?

Gasses, water, soils, and geothermal energy along with volcanic soils

43

How many volcanic eruptions are there around the world every year?

50 to 60

44

What are the sources of magma for volcanism?

Continental to Oceanic crust collisions
Oceanic to Oceanic collisions
and a little at Continent to Continent

45

What are the volcanic activity levels?

Active, Dormant, Extinct, and also Mantle Plumes

46

What defines an ACTIVE volcano?

current or recent activity (historic)

47

What defines a DORMANT volcano?

Activity within the last 1000 years, and expected to erupt in the future

48

What defines an EXTINCT volcano?

Not expected to erupt again, sometimes extensive erosion

49

What is a Mantle Plume?

Stationary hot spot (Hawaii), massive undersea landslides common (TSUNAMI)

50

What is the most common type of lava?

Basaltic

51

What are Basaltic Eruptions like?

effusive, non-explosive

52

What are the characteristics of Basaltic Lava?

very fluid flow, travels long distances

53

How do Basaltic Eruptions erupt?

usually long cracks and flank fissure eruptions, no major cones

54

Where are there shield volcanoes?

Hawaii and the Snake Plain

55

What are the two Basaltic Lava Flow types?

aa (ah ah) and pahoehoe (pa hoy hoy)

56

What are the characteristics of an aa lava flow?

jagged, cindery flows, more viscous

57

What are the characteristics of a pahoehoe lava flow?

ropey surface (smooth on bare feet) with lava tubes underneath

58

What makes up a typical Basaltic Flow Architecture from bottom to top?

The Collonade (Columnar Basalt), the Entablature, and the Scoria

59

What happens when Basaltic lave enters water

Pillow Basalts

60

What are Andesitic lava flows like?

flow slowly for short distances

61

Which type of volcanoes are Andesitic?

Stratovolcanoes (Composite Cones)

62

Are Andesitic eruptions explosive?

Yes

63

What kind of eruptions are common in Andesitic?

Pyroclastic Eruptions

64

What is tephra?

All lava fragments

65

Ash?

sand and silt sizes

66

Cinders?

pebbles

67

Bombs and blocks?

large pieces

68

What is tuff?

Solidified tephra

69

What are pyroclastic flows?

avalanches of hot material

70

What are Lahars?

Volcanic Mudflows

71

What makes up a lahar?

pyroclastic material and water

72

What is Rhyolitic lava like?

highly viscous, high silicon, low temperature

73

What can appear before a rhyolitic eruption?

lava dome

74

What are the secondary hazards of volcanism?

Temporary global cooling and volcanic gasses

75

What causes most of the global cooling after a large eruption?

tiny aerosols of SO2

76

What is the origin of mafic igneous rocks?

divergent oceanic plates, MORBs

77

Where are andesites and diorites found?

near subduction zones

78

Why are andesites and diorites found near subduction zones?

The subducted water helps to partially melt the upper mantle

79

Where are rhyolites and granites found?

on continents near modern/ancient subduction zones

80

What is weathering?

atmospheric agents cause rocks and minerals to break down

81

What is erosion?

water, wind, ice, or gravity move materials produced by weathering and deposit them elsewhere

82

What is Loess?

wind-blown, silty soil

83

What is the difference between an outcrop and a formation?

an outcrop is an exposed mass of rock and a formation is a distinct mappable unit

84

What is the difference between mechanical and chemical weathering?

mechanical weathering just breaks it down into smaller pieces, while chemical actually changes the chemical composition of rocks or minerals unstable at earths surface

85

How do mechanical and chemical weathering work together normally?

mechanical adds to the surface area that chemical can act upon

86

What are the different mechanical weathering processes?

Frost wedging, Salt crystal growth, Root wedging, Thermal expansion, Mechanical exfoliation, and Abrasion

87

What is mechanical exfoliation?

pressure unloading on plutonic masses (popping off surface or rock bursts at depth)

88

What are the different chemical weathering processes?

Dissolution and Carbonic Acid

89

What is Dissolution?

Water "dissolves" ions from the rock/mineral and carries it away

90

What stone is particularly vulnerable to carbonic acid?

limestone because of the calcite

91

What is Hydrolysis?

water breaks down and replaces other ions in mineral structures

92

What does hydrolysis do to granite?

turns it into grus

93

What is Oxidation?

mineral ions combine with oxygen ions (rust)

94

What is Acid Mine Drainage?

Sulfuric acid from mines comes up and joins with surface and groundwater

95

What is the Regolith?

The "rock blanket" of fragmented material that overlies bedrock

96

What is soil?

the upper few meters of the regolith that contains both mineral matter and organics

97

What causes soil horizons?

substances are dissolved and transported to deeper levels by water, forming weathering zones

98

What are the most common soil horizons?

O, A, E, B, C

99

What defines the O horizon?

Very organic, carbon rich, plant material

100

What is the A horizon?

inorganic mineral matter and humus

101

What is humus?

Carbon rich, dark, derived from organics in O horizon

102

What is the E horizon?

Zone of eluviation, lighter color, barely any organic matter

103

What is the B horizon?

Material transported down either mechanically or dissolved, illuviation, concentrated calcite

104

What is the C horizon?

lowest zone of significant weathering, partially weathered parent material

105

What are the two old classifications of soil?

Pedalfers (aluminum and iron, organic, fertile) and Pedocals (caliche layer, thin, arid climate)

106

What are the modern soil classifications?

Vertisols (high clay), Entisols (young soils), Paleosols (ancient, reflect climate changes), and oxisols (tropical)

107

___% of rocks exposed on land surface are sedimentary

75%

108

Sedimentary rocks are ___% of crustal volume

5%

109

What is clastic grain size controlled by?

the original rock type and the transport energy

110

How does wind sorting compare to ice sorting?

wind sorting is very good (frosted grains) but ice sorting is very poor