Geo Unit 2 Flashcards
(110 cards)
1
Q
Igneous rocks make up ___% of the outer 50 Km of Earth
A
95%
2
Q
Difference between Lava and Magma
A
Lava is on the surface of the Earth, Magma is plutonic
3
Q
What is Magma?
A
Molten liquid, crystals, and gas
4
Q
What are the different textures of Igneous Rocks?
A
Aphanitic, Phaneritic, Porphyritic, and Volcanic Glass
5
Q
Aphanitic Igneous Rocks
A
very small mineral grains
6
Q
Phaneritic Igneous Rocks
A
Large, visible mineral grains
7
Q
What is Texture?
A
The arrangement, size, and shapes of mineral grains
8
Q
What causes Volcanic glass?
A
VERY rapid cooling
9
Q
Porphyritic Texture?
A
Large and small mineral crystals/grains
10
Q
How do you determine the origin of Igneous rocks?
A
Look at the mineral grain sizes
11
Q
What is the basis for NAMING Igneous Rocks?
A
The Silica Content
12
Q
What are the three composition classifications for Igneous Rocks?
A
Felsic, Intermediate, and Mafic
13
Q
Felsic Igneous Rocks?
A
Light color and Silicon-rich
14
Q
Mafic Igneous Rocks?
A
Dark color and Silica-poor
15
Q
Felsic and Phaneritic?
A
GRANITE
16
Q
Felsic and Aphanitic?
A
RHYOLITE
17
Q
Intermediate and Phaneritic?
A
DIORITE
18
Q
Intermediate and Aphanitic?
A
ANDESITE
19
Q
Mafic and Phaneritic?
A
GABBRO
20
Q
Mafic and Aphanitic?
A
BASALT
21
Q
What things are part of the creation of magma?
A
Heat, Pressure, and a small amount of Water
22
Q
Why is water part of Magma Creation?
A
A small amount of water allows rocks to melt more easily
23
Q
What is the melting point of felsic minerals, and when is it reached?
A
700 degrees Celsius, and reached around the crust/mantle boundary
24
Q
What is decompression melting?
A
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
