1
Q
what are sediments comprised of
A
loose fragments of rocks or minerals, shells/shell fragments, or mineral crystals that precipitate out of water
2
Q
how is sediment produced
A
weathering
3
Q
what can bedrock be transformed into
A
soil, after lots of weathering
4
Q
different clasts
A
-finest is mud and largest is boulders.
-mudstone is finest
-sandstone is made up of quartz… fine and coarse depending on clast size.
5
Q
what is physical weathering
A
-mechanical weathering
-breaks rocks into unconnected clasts of different sizes.
6
Q
physical weathering processes
A
jointing, salt wedging, frost wedging, root wedging, and thermal expansion
7
Q
what is jointing
A
-joints are natural cracks in rocks from the expansion of a rock or cooling/contraction
8
Q
what is exfoliation (jointing)
A
-when jointing develops in layers parallel to the surface due to pressure release, exfoliation occurs.
-thin layers
9
Q
bedding vs vertical joints vs exfoliation joints
A
bedding: horizontal layers/cracks in sandstone
Vertical joints: same as bedding but VERTICAL
Exfoliation joints: curvier joints on granite. Surface is more horizontal than the sandstone which is on the side of a block making the lines we see
10
Q
what is salt wedging
A
-creates “honeycomb withering”
-happens in arid climates and coastal areas
-when salt dissolved in water precipitates and exerts a force on the surrounding rocks.
11
Q
what is frost wedging
A
water expands 9% when frozen, exerting a force on the surrounding rocks.
-blocks are lifted and pushed out
12
Q
what is root wedging
A
-as roots grow, they exert a force on the surrounding rock.
-the blocks eventually tumble off the base of the cliff
13
Q
what is thermal expansion
A
-when minerals expand and contract at different rates from temperature changes leading to cracks.
14
Q
what is dissolution
A
-minerals dissolved into water.
-mostly affects carbonate rocks and salts.
-iron in the water can start attaching to crystal surfaces and begin dissolving
15
Q
what is oxidation
A
-reactions during which an element loses an electrons
-usually happens when elements combine with oxygen
16
Q
where is oxidation common in
A
-iron-bearing minerals
17
Q
hydrolysis
A
-another form of chemical weathering that affects silicate materials
18
Q
what do physical and chemical weathering work together to do
A
- increase surface area (physical)
- dissolve minerals and cements (chemical)
- alter hard minerals into soft minerals (chemical)
19
Q
as rocks break apart, what does an increase in surface area allow?
A
-chemical weathering to happen faster
20
Q
where is weathering the fastest
A
on the corners of a block is faster than a flat face
21
Q
difference between physical and chemical weathering
A
-physical: breaks rocks into pieces without changing the composition
-chemical: alters minerals through chemical reactions
-they can happen simultaneously
22
Q
sawtooth weathering profiles
A
-develop in sequences of alternating strong and weak layers (exposure in New Mexico)
-weak layers (shale) are indented, strong layers (santstone) protrude
23
Q
granite vs felspar vs calcite weathering resistance
A
granite: can have quartz which is resistant
feldspar: will break down
calcite: weak
24
Q
granite headstone vs marble headstone
A
granite: inscriptions last for centuries
marble: inscriptions weather away in decades
25
when does soil form
-debris production
-interaction with water
-interaction with organics
26
what are horizons
they are produce from what forms soil (debris production, interaction with water and organics).
-they are seen in a soil profile
27
what are the layers of soil
solid then weathered bedrock, subsoil, transition, topsoil, grass.
28
(soil) lots of rain means lots of _
leaching
29
what accumulates in the zone of accumulation after rain
ions and clay (get transported by downward percolating (filter gradually) water)
30
what is the zone of leaching
-layer just beneath topsoil where soluble nutrients and minerals are dissolved by water and carried downward.
31
what is the zone of accumulation
-minerals leached down from top layers are deposited and accumulate.
-usually has higher clay content
32
younger vs older soil
-younger is thinner than older
33
thicker soil develops over a _ substrate and _ _
-weaker
-gentler slopes
34
what is important to substrate (foundation or base for another process or substance)
-mineral composition and resistance to weathering are important
35
slope steepness effect of soil
-regolith (loose layer of soil that covers the bedrock) easily washes from steeper slopes.
36
what do wetter soils contain?
-more organic material
37
what do flat soils tend to hold (and develop thick or thin?)
-more moisture and develop thicker soils
38
explain composition of desert soil
-unweathered bedrock at the bottom
-near the surface, calcite accumulates to form concrete (right under sand)
39
explain composition of temperate soil
-unweathered bedrock at the bottom
-zone of accumulation: iron oxide and aluminium oxide accumulate; calcite is leached
-humus accumulates at surface
40
explain composition of tropical soil
-unweathered bedrock underneath weathered bedrock
-iron-oxide, aluminum-oxide, and aluminum-hydroxide residue are in leaching zone.
41
3 different types of soil on increasing rainfall
low: desert
middle: temperate
highest: tropical
42
soil conservation practices (5)
1. protecting soil with cover or mulch after harvest (protect from drying out and running off)
2. no-till farming practices (planting into residue of used soil)
3. decreasing runoff (erosion barriers)
4. planting windbreaks of hedges or trees
5. mixing organic carbon back into soil
43
what does sedimentary rock make
layers! if you can see the layers it is sediment
44
what is mount tambora
-volcano in indonesia
-killed almost 100k in 1800s
-large summit caldera
45
where do sedimentary rocks occur
-uppermost part of the crust
46
what do sedimentary rocks cover
-igneous and metamorphic basement rocks
47
what kind of rock is the dolomites
-limestone
-sedimentary
48
what are evaporites
-chemical sedimentary rocks
-form when saline waters (lake, marine) evaporate causing dissolved minerals to crystallize and precipitate out of the solution
49
what are evaporites rich in (+ examples)
-rich in minerals
-halite, gypsum, anhydrite, calcite
50
what provides the raw material for all sedimentary rocks
-physical and chemical weathering
51
4 sedimentary rock classes
-clastic: loose rock fragments (called clasts) cemented together
-biochemical: cemented shells of organisms
-organic: carbon-rich remains of once-living organisms.
-chemical: minerals that crystallize directly from water
52
what do clastic rocks consist of
-mineral grains, rock fragments, and cementing material
53
what does lots of clay compacted together form
shale
54
what are the mesa verde national park rocks
-sandstone cliff dwellings
55
how are clastic sedimentary rocks created (5 ways)
-weathering
-erosion
-transportation
-deposition
-lithification
56
explain weathering for creating clastic sedimentary rocks
generation of detritus via rock disintegration
57
explain erosion for creating clastic sedimentary rocks
removal of grains
58
explain transportation for creating clastic sedimentary rocks
dispersal of solid particles and ions by gravity, wind, water, and ice
59
explain deposition for creating clastic sedimentary rocks
settling out of the transporting fluid
60
explain lithification for creating clastic sedimentary rocks
transformation into solid rock
61
explain the key stages and process of forming sediment (diagram on ions and particles being transported)
-weathering and erosion causes particles and ions to be transported in surface water
-these are deposited into the water
-ions are transported in groundwater and enter the sediment underwater from the bottom while others enter from the top
62
course and fine grained for deep/shallow sediment
shallow is course, deep is fine
63
what does lithification do to sediment
it turns loose sediment into solid rock
-burial increases pressure, squeezes out air and water, and compacts grains
64
explain compaction and cementation happening at sea floor
-weight of the water on substrate compact, and ions are coming in from moving groundwater act as glue
-sediment is most voluminous near the floor and space out as it reaches the surface
65
what do minerals precipitate into (from groundwater), and what are the minerals
-often quartz or calcite
-this cement glues the loose sediment together
66
what is grain size a measure of
-the size of fragments or grains
67
categorize sand, clay, silt, and gravel from course grained to fine grained
gravel, sand, silt, clay
68
as transport distance increases, grain size _
decreases
69
what does a variety of different clast composition hint at
source area and transport processes.
70
what can clasts be compromised of
individual mineral grains or rock fragments containing several mineral types
71
what is angularity
-degree of edge or corner smoothness
72
what is sphericity
the degree to which the shape of a clast approaches that of a sphere
73
what to angularity and sphericity indicate
-how far the sediment was transported
-angular and non-spherical are not transferred far
74
levels of angularity
1. angular
2. subangular
3. subrounded
4. rounded
75
what is sorting
measure of the uniformity of grain sizes in a sediment population
-degree of sorting increases with transport distance
76
breccia
-course, angular rock fragments
-the angularity indicated the absence of rounding by transport.
-therefore they are transported close to clast source
77
conglomerate
-rounded rock clasts
-clasts are rounded as flowing water rounds off corners and edges
-deposited farther from source than breccia
78
arkose
sand and gravel with abundant feldspar
-usually deposited in alluvial fans
-composed of feldspar and quartz
79
sandstone
clastic rocks made from sand sized particle
-quartz is by far the most common mineral in sandstone
80
what are fine clastics composed of
silt and clay
-silt sized sediment is lithified to form siltstone
-clay sized particles form mudstone or shale
81
what kind of rock are the sediment of clam shells
limestone (calcium carbonate)
82
what are biochemical sedimentary rocks made of
-sediments derived from shells of once living organisms
-hard mineral skeletons accumulate after death of the organism
83
what is limestone (made of, used by organisms?)
-made almost entirely made of calcite or aragonite
-most common materials used by organisms that make seashells
-preserves the shell of fossils sometimes in great abundance
84
where does biochemical limestone form
-in warm, tropical, shallow, clear, oxygen rich, marine water
-calcium carbonate in limestone comes from shells
85
textures of limestone
-fossiliferous limestone
-micrite
-chalk
86
what is chert
-rock made of cryptocrystalline quartz derived from opaline silica from the skeleton of some plankton
-can occur in beds or modules
-has all the properties of quartz, including hardness and conchoidal fracture
-very sharp (used to make tools)
87
if plankton is carbonate, it will be _, but if it's silica it will create _
-chalk
-chert (a quartz)
88
what is micrite
-deposited far from source
-similar to mud
-fine grained
-calcite
89
what are organic sedimentary rocks made of (and examples)
-organic carbon (soft tissues of living things)
-rocks include coal, altered vegetation, oil shale
90
what are chemical sedimentary rocks comprised of
-minerals precipitated from water solution
-have crystalline (interlocking) texture developed from initial crystal growth from solution, which may be recrystallized during burial
91
what are evaporites derived from
-water and salt come from stream in mountain into sea/lake
-water evaporates and salt precipitates, so salt builds up
-example: floor of Death Valley in california (looks like snow)
-include halite and gypsum
92
what is travertine
-when calcium carbonate reaches the surface from groundwater, the CO2 is released into atmosphere
-this causes the dissolved calcium carbonate to react with bicarbonate and precipitate out which builds up travertine
-occurs in thermal springs and caves
-yellowstone - terraces at mammoth hot springs and lewis & clark caverns
93
world's largest deposit of travertine
-anatolia turkey (cotton castle)
-earth's crust is pulling apart
94
Replacement chert
-does not originate from living things
-flint - black/grey from organism matter. silica is dissolved and precipitated in chalk and flint forms.
-jasper - bright red or yellow from iron oxides
-petrified wood - original wood grain preserved by. silica. silica gets in from eroding water rich in silica, which goes into tree and replaces everything in there.
-agate - forms concentrically layered rings
95
petrified wood forest spoken about in class
-petrified forest national park in arizona
-loots of volcanism, ash from eruptions
-the composition of ash/tuff is from felsic rocks full of silica and after millions of years the water becomes silica rich and replaces everything
96
when do sedimentary structures from and what are they useful for
-when sediments are deposited
-useful b/c they provide strong evidence abt conditions in the depositional environment
97
what are redbeds
-reddish sanstone and shales
98
what do bedding and stratification features include?
-surface features on bedding layers and the arrangement of grains within bedding layers
99
what is a bedding plane
-when sedimentary rocks are layered or stratified similar to horizontal beds, it is the boundary between 2 beds
100
what does bedding look like
-bands or stripes that can be traced laterally across an outcrop
101
what is bedding reflecting of
-changing conditions during deposition
-may be in transporting medium, sedimentary source
-results in changes to sediment composition
102
explain the possible layering
-silt is deposited during normal river flow
-then, gravel during flood
-then another layer of silt
-eventually turns to layers of rock and you can see the different beds, or layers
103
what are formations
when rock units are so unique that they are recognized and mapped over large regions
-named for the places they are most exposed
104
what are the fine particles in the formation of bedding
silt and mudstone, the last to form
105
transgression vs regression for rivers
transgression: stream moves over land
regression: stream moves away from land
106
what does all the pressure do to the first layer of bedded rock
-becomes metamorphic
107
what is the grand canyon called (video)
a chasm
108
what creates bedforms (reflective of and indicate)
-water flowing over loose sediment
-reflects flow velocity and grain size
-useful indicators of environmental conditions
109
what are ripple marks and dunes
-ridges and troughs that develop perpendicular to flow in sandy sediments (cms)
-dune are a larger scale of ripple marks (50-100cm)
110
what do ripple marks tell you
-current direction
111
in ripples/dunes, if you can see the cross beds and layering what does that mean
it is sedimentary
112
why are beach ripples asymmetrical
-they are constantly going back and forth
-look at sand ripple symmetry to see what body of water it was formed by
113
is the current perpendicular or parallel to the layers
perpendicular, leading to cross bedding
114
what is Uluru/ayers rock
-sandstone monolith
115
what are cross beds
-created by ripple and dune migration
-sand moves up gentle side and piles at the crest
-slips down steep face
-slip face moves down current and is buried by the next avalanche of sand
-slip faces are preserved as cross beds
116
what does cross bed orientation indicate
-wind direction at the time of deposition
117
what are turbidites
-layers of sediment deposited by powerful underwater avalanches of sediment called turbidity currents
118
what are turbidity currents
-they form in deep basins that get periodic pulses of turbid water
-as pulse wanes, water loses velocity and the grains settle
-sediment and water flows chaotically downslope
119
in turbidity currents, what settles first
-coarse material, fine is last
120
what does the process of turbidity currents form
-graded beds (coarse to fine upwards)
121
submarine canyons
-valleys that cut into seabed, form by turbidity currents
-when turbidity current slows it deposits sediment in a submarine fan
122
what are mud cracks
-a cooling feature
-they are like columnar basalts
-they shrink into their shapes
123
what do mud crack indicate
-wet and dry terrestrial conditions
124
when do the scour marks form
-when debris is dragged along the bottom of a river
-they are filled in with sediment and can make casts
125
what are depositional environments
-locations where sediment accumulates
126
depositional environments: shale
-the most fine
-must be in low energy environment to settle
127
depositional environments: siltstone
-second most fine
-finer than sand, coarser than shale
128
depositional environments: sandstone
-3rd finest
129
depositional environments: conglomerate
-4th finest (is coarse)
130
depositional environments: fossiliferous limestone
-the most coarse
-reefs form fossiliferous limestone
-biological material becomes the rock
131
what happens when currents are really beat up and form far out, breaking up the coral
makes calcium carbonate
132
what happens to sediment in glacial environments
-sediments are created, transported, and deposited by actions of moving glacial ice
133
what is glacial till
-poorly sorted mixture of all grain sizes (gravel, sand, silt, clay)
-when glaciers suddenly melt and create a mess of everything it carried
134
what is most common in stream environments
-breccia (sharp, angular)
-conglomerate (rounded)
135
what happens in mountain stream envrionments
-water carries large clasts during floods
-during low flow, cobbles and boulders are immobile, and course conglomerate is a characteristic of this
136
what are alluvial fans
-cone-shaped wedges of sediments that pile up where a rapid drop in stream velocity occurs at a mountain front
137
what is most of the alluvail fan
-broken down pieces, feldspar and quartz
-quartz is resistant to weathering but the feldspar is not
138
how do dunes move, what do they result in
-according to winds
-result in uniform sandstones w gigantic cross beds
139
what do river environments preserve
-evidence of channelized sediment transport
140
what is sorted near shore and deposited in deeper water
shore: gravels and sands
deeper: well-sorted muds
141
where does sediment accumulate in a marine delta environment
-where river velocity drops upon entering the sea
142
where do shallow-water carbonate environments develop, and what will form
-in warm, clear, shallow, normal salt level, marine water
-will form fossiliferous limestone
143
if the carbonates are so broken down and fine, what can form when it goes deep
-micrite
144
what do fine silts and clays lithify into in deep-marine environments
-shale
145
what do skeletons of planktonic organisms make
-chalk or chert
146
what is plankton
chalk
147
what are the chalk cliffs in england
-made from chalk from the compacted skeletons of marine organisms
148
rift basins form...
at divergent plate boundaries
149
passive margins are...
-the edges of continents that are not tectonic plate boundaries
150
intercontinental basins form...
-in the interior of the craton, far from continental margins or tectonic plate boundaries
151
foreland basins form....
-on the craton of collisional mountain belt
152
range vs basin
-range: high part, mountain
-basin: low part, where the crust was sunken between faults. sedimentary rocks form here
153
sea level rise vs fall
rise: transgression (sea comes over the land)
fall: regression (shifts environment towards basin)
154
explain the process of sea level rising and its effect on the shoreline, basin, and land
-floor of basin subsides (lowers)
-shore migrates inland, and overlap terrestrial environments
-erodes the land and forms a cayon that exposes the layers (like coal, sandstone, rebdeds)
-cause of swamps and floodplains
155
diagenesis
-physical, chemical, and biological changes that turn loose sediments into rock after deposition but before metamorphism
156
which has nothing to do with calcite: chalk, micrite, chert, aragonite, and fossiliferous limestone?
-chert, it is made of quartz, therefore silica
157
what is the step before metamorphic?
diagenesis
158
what are metamorphic rocks
-rocks that undergo solid-state alteration of preexisting rock (change - meta, form - morphe)
159
protoliths
-the preexisting rocks that are altered during metamorphism
160
what changes do protoliths undergo
-texture and mineralogy
161
are protoloiths and metamorphic foliated or non foliated
non-foliated
-metamorphic is foliated
162
what are the changes in texture and mineralogy due to
temp, pressure, tectonic stress, and reactive water
163
what does a protolith change from a red shale, made of quartz, clay, and iron oxide turn into after metamorphism
-made of quartz, feldspar, biotite, and garnet
164
what does the texture change create
-intergrown and interlocking grains
165
what is the texture change in a limestone (calcium carbonate)
-heat dissolves the shells and crystallizes it, the rock becomes a marble
166
what is foliation (metamorphism slides)
-defined as alignment of platy materials (micas) or creation of alternation light and dark bands
-it is a planar fabric that cuts through the rock
167
is marble foliated or non foliated
non-foliated
168
without pressure, is there alignment?
no. need pressure for them to align
169
what happens during recrystallization
-minerals change size and shape through dissolution and growth of crystals
-composition does not change
170
what happens to the grains when limestone metamorphoses into marble
the tiny clasts turn into large, new grains
171
what is neocrystallization
-the formation of new (metamorphic) minerals from old (in the protolith)
172
what happens to protolith minerals in neocrystallization
-become unstable and undergo chemical reactions that recycle elements to form a new assemblage of minerals
173
example of the neocrystallization from clay and quartz
-clay and quartz are shale, turn into quartz, garnet, and mica schist
174
how to get garnet from quartz
-take the silica and oxygen from quartz, and combine the silica with iron
175
what happens during a pressure solution
-mineral grains partially dissolve where their surfaces press together
176
what happens to dissolved ions in a pressure solution process
-they migrate in a thin water film and re-precipitate in areas with low pressure. it requires small amounts of water
177
what happens to spherical grains during metamorphism (pressure solution)
-become elliptical grains
-they get pushed into strips and the circles become more oval like
-there is new growth between the ovals in the strips, and the edges of the ovals dissolve
178
what happens to minerals during plastic deformation
-mineral grains soften and deform when the rock is squeezed/sheared at higher temps and pressure
-same as pressure solution however there is no dissolving edges and no defined strips, and no new materials
-the minerals change shape without breaking
179
do sedimentary and igneous have alignment
no
180
what are the agents of metamorphism
-heat
-pressure
-compression and shear
-hydrothermal (hot water) fluids
181
what is the bedding in shale
-slate
-if the shale has bedding, the slate will have it too
181
do all four agents of metamorphism need to be present for it to occur
no, but they can co-occur
182
what are the 5 levels/rocks from lowest to highest temperature and pressure
1. schist
2. gneiss
3. migmatite
4. hornfels
5. mylonite
183
what is half metamorphic and half igneous
-migmatite
184
what forms around a hot magma body
hornfels
185
what happens for mylonite
rocks sliding (transform fault). the intense pressure causes rocks to crack up and can flow like plastic.
186
where will mylonite always be found
sites like earthquakes
187
what in hornfels shows the metamorphism
-the colour change in the middle
188
where do you only have intense pressure and low temps (during metamorphism)
at convergent boundaries (right at surface)
189
where does blueschist form
-convergent boundaries (low temp, high pressure)
190
what forms at high temp, low pressure
hornfels
191
what forms at low temp, low pressure
shale
192
rate schist, gneiss, slate, and migmatite from low temp, low pressure, to high temp and high pressure
1. slate (low and low)
2. schist (medium)
3. gneiss (higher temp and pressure)
4. migmatite (highest temp and pressure)
193
why do kyanite, andalusite, and sillimanite have the same chemical composition but different crystal lattice structures
-chemical composition is the same cause they are polymorphs
-lattice is different cause they form under different temp/pressure
194
what temp and pressure is needed for mineral change in andalusite, kyanite, and sillimanite
-andalusite: low temp and low pressure
-kyanite: low temp, high pressure
-sillimanite: high temp and high pressure
195
what is differential stress
stress that is greater in one direction
196
why is differential stress different than pressure
pressure is equal in all directions, differential stress is greater in one direction
197
what is differential stress a common result of
-tectonic forces
-mountain building creates horizontal compression (push)
-rifting creates horizontal extension (pull)
198
what are the different kinds of differential stress
-normal: perpendicular to surface. Compression is pushing together normal stress. Tension is pulling apart normal stress
-shear: acts parallel to surface. press and move
199
what causes minerals and rocks to change shape without breaking
-compression and shear combined with higher temp and pressure
200
internal textures are changed as minerals...
-rotate or dissolve and recrystallize in preferred orientations
201
what directions do grains grow relative to stress
in opposite direction of stress
202
what does differential stress do to inequant minerals
-the shapes align in preferred orientations
203
how does hydrothermal fluid affect metamorphism
accelerates it
204
what is hydrothermal alteration called
metasomatism
205
what do quartz veins indicate
hydrothermal fluid action
206
what is hydrothermal fluid made of, what does it do to chemical reactions, and what does it add or subtract
1. hot water with dissolved ions and volatiles
2. speeds up chemical reactions
3. adds or subtracts elements
207
why does foliation develop on metamorphic rocks
-the rocks have been subjected to differential stress
-they have a lot of platy minerals
208
foliation on slate
-called slaty cleavage
-forms perpendicular to compression through parallel clay alignment
-weak at folliated point, make great shingles from getting broken at cleavage plane
209
what is phyllite
-fine grained, mica rich rock
-forms by metamorphic alteration of slate
-silky sheen called phyllitic luster
210
what do the clay minerals in slate neocrystallize into
tiny micas
211
what happens to phyllite under further metamorphism
turns into schist
212
what is a metaconglomerate
a metamorphosed conglomerate
213
what happens in a metaconglomerate (and foliation is defined by...?)
-gravel clasts are flattened by pressure solution and platic deformation
-foliation is defined by the flattened gravel clasts
214
what is schist
-fine to coarse
-crystalline rock
-larger micas (meaning medium to high grade metamorphism)
215
common minerals in schsit (7)
-muscovite
-biotite
-quartz
-feldspar
-kyanite
-garnet
-amphibole
216
in foliated gneiss, what are the bands made of
-felsic materials: quartz, feldspar
-mafc: biotite or amphibole
217
how is compositional banding developed
-extensive high temperature shearing
-metamorphic differentiation
218
how is foliation created during formation of gneiss
-rock is sheared under high temps
-original contrasting rock types in protolith are smeared into parallel layers
219
what happens during solid state diffusion to create compositional banding
-chemical reactions segregate light and dark colours
220
what is a migmatite and its features
-partially melted gneiss
-igneous and metamorphic
-felsic bands recrystallize in migmatite which is how it has igneous and metamorphic
221
what are the sculptures of michelangelo made of
-marble
-from marine organisms with calcite shells that were buried and lithified making limestone
-limestone was pushed below surface and underwent metamorphism, becoming marble
222
what is quartzite
-nonfoliated metamorphic rock
-metamorphic quartz sandstone
-sand grains recrystallize and fuse to form a hard, glassy, resistant rock
223
why do non-foliated metamorphic rocks have no planar fabric evidence
-cause they lack inequant minerals and/or they recrystallize without differential stress
224
what is marble made of
-coarse crystalline calcite or dolomite from a limestone
225
what is metamorphic grade a measure of
-the intensity of temp and pressure leading to alterations
-low grade: slight
-high grade: intense
226
what is a metamorphic facies
set of mineral assemblages that indicate temp and pressure conditions
227
what goes through contact (thermal) metamorphism
hornfels (high temp low pressure)
228
what is formed at a volcanic arc
granulite (high temp and pressure)
229
wha is formed at a collisional mountain belt
amphibolite (medium pressure a bit higher temp)
230
what forms in a stable continent
greenschist
231
what is formed at an accretionary prism
blueschist
232
what is thermal metamorphism
-heating by a plutonic intrusion
-hornfels
233
what is burial metamorphism
-deep burial in a basin
-blueschist
234
what is dynamic metamorphism
-shearing in a fault zone
-mylonite
235
what is regional metamorphism
-pressure and temp change due to orogenesis (mountain formation)
-slate, schist, gneiss
236
what is hydrothermal metamorphism
-alteration by hot water leaching
-quartz
237
what is subduction metamorphism
-high pressure and low temp alteration
-blueschist
238
what is shock metamorphism
-extreme high pressure from a bolide impact
-quartz
239
what is contact (thermal) metamorphism due to
-heat from a body of magma invading host rock
240
what does contact metamorphism create
-zoned bands of alteration called a contact aureole
-zoned from high grade (near pluton) to low grade (away from pluton)
-metamorphic grade decreases with distance from intrusion
241
what breakage of rock does dynamic metamorphism involve (rocks in shallow vs deep crust)
-shearing within a fault zone
-at the crust, rocks are brittle and crush to form fault breccia
-deeper crust, rocks are ductile
242
what do rocks in fault zones smear to form
mylonite
243
when does dynamothermal metamorphism occur
-during development of mountain belts
-also called regional metamorphism
244
what creates more metamorphic rock than any other mechanism
-heat and pressure of orogenesis
245
what is hydrothermal metamorphism and what does it produce
-hot chemically agressive water chemically alters the basalt
-produces greenish minerals like chlorite and epidote
-sulfide precipitates from the surface
246
what is the process of hydrothermal metamorphism
-cold ocean water seeps into the fractured crust
-heated by magma, the water reacts with the mafic rock and is ejected by black smokers
-mafic rock is altered
247
what conditions do subduction metamorphism create
-low temp high presure
-blueschist
248
exhumation (process)
-metamorphic rocks returning to the surface
-as continents push together, the rock is pushed up
-rock at depth warms up/softens, and the mountain belt collapses (like cheese under sun)
-erosion removes the rock/flattens it
249
shields
-large regions of ancient, high-grade metamorphic rocks that are exposed in continental interiors
-eroded remnants of orogenic belts
-they form the basement under sedimentary cover over most of the world
250
what is the rock cycle
-progressive transformation of earth materials from one rock to another over time
251
if you heat and melt sedimentary rock it becomes....
igneous
252
when igneous rock undergoes erosion, transportation, and deposition it becomes...
sedimentary
253
when you bury and/or heat igneous rock it becomes...
metamorphic
254
when you melt metamorphic it becomes...
igneous
255
when metamorphic rock undergoes erosion, transportation, and deposition it becomes...
sediment
256
when sediment is buried and heated it becomes
metamorphic
257
example of rock life cycle (mantle plume atoms)
-atoms rise to surface and erupt via mantle plume
-erosion makes sediment from the igneous erupted material
-the sediment get subducted into mantle
258
rock cycle example for continental collision
-sedimentary rocks end up at depth and become metamorphic
259
rock cycle example from exhumation
-metamorphic rock exposed at surface, when undergoes weathering and erosion
260
can you create or make anything disappear at transform fault
no, but can make mylonite from the shearing
261
if you have lots of shale around a pluton it will make
hornfels
262
continental rifting rock cycle example
-rifting causes the crust to stretch and break
-crustal rocks partially melt from the heat transferred from the crust
-some metamorphic rock melts creating igneous
263
4 driving forces of the rock cycle
-earth's internal heat (drives plate movement and creates mantle plumes)
-gravity (helps drive plate movements and affects surface processes)
-sun (wind, rain, ice, weathering and erosion)
-life (oxygen to atmosphere aids in weathering)
264
what are fossils
-remnants or traces of ancient living organisms
-created by burial with rock material and preserved after lithification
265
where do most fossils occur
-sediment
-some in air-fall ash deposits
266
stages of fossilization in dinosaur
-footprints left
-dino dies
-flesh rots, bones remain
-water rises, sediment buries bones and footprints
-sediment accumulates over bones and they eventually fossilize
-erosion exposes the bed containing the bones and footprints
267
baby mammoth fossil example
-1 meter
-found in Siberia, died 37k years ago
268
fossil examples preserved in tar or amber
-tar: ground sloth in California
-Amber: insect from 200 million years ago embedded in amber
269
what are fossil shells
-hard parts of invertebrates
270
carbonized impressions
-flattened molds or casts are created when soft organisms are pressed between sediment layers
-a thin film of carbon stays on the surface of impression
271
permineralization
-fossil process where dissolved minerals fill the spaces in an organisms organic tissue and creates a 3d fossil that preserved internal structure
-any quartz kind of mineral in petrified wood
272
in permineralization where do minerals precipitate
-in porous material, wood or bone usually
273
how are trace fossils formed
-by the action of an organism (footprints, burrows, feeding marks)
274
macrofossils vs microfossils
-macro: large enough to see
-micro: need a microscope
275
how can you date geological materials
-qualitatively
-qualitatively
276
relative ages vs numerical ages
-relative: based on order of formation
-numerical: actual number of years
277
what does the principle of fossil succession describe
-the predictability of fossil distribution through time
278
what are index fossils
-diagnostic of a particular geological time
279
what does fossil range describe
-first and last appearance of a species
280
succession of rocks in grand canyon
-starts with schist
-sandstone
-shale
-limestone
-red beds and limestones
-shale
-sandstone
-limestone
281
major eon, then era, then period and epoch we live in
1. phanerozoic
2. cenozoic
3. quaternary
4. holocene
282
major eon, then era, then period and epoch dinos are from
1. phanerozoic
2. mesozoic
3. cretaceous, jurassic, triassic
283
when did life first appear on earth
3.8 Ga (billion)
284
first multicellular life, first hard shells
1. 700 Ma
2. 542 Ma
285
what did shells do for the fossil record, and what happened quickly after shells emerged
-improve fossil preservation
-life quickly diversified (after cambrian explosion)
286
stable isotopes vs radioactive
-stable never change (carbon 13)
-radioactive spontaneously decay into other elements (carbon 14)
287
what do we use for radioactive dating
-parent decay into daughter
-use the ones that will change and decay into something else
288
what is half life
-time it takes for half of the parent to decay. (half of the unstable nuclei)
-as parent disappears the daughter grows in
289
how is the age of a mineral determined
-by measuring the ratio of parent to daughter isotopes
-uranium and led are the most common
290
rhythmic layering
-layers in sediment or ice
-used to count numerical dates (like tree rings)
-not great
291
what is unconformity in dating
when they have absolutely no idea
292
how long have relative dating vs numerical age dating been used
-relative: hundreds
-numerical: 60
293
geochronology limits
-must be on igneous or metamorphic
-can only date specific rocks within sediment
294
Distinctive sequence of strata that can be traced across a large region
-formation
-multiple formations is a group
295
Pick out rock that is nonfoliated. phyllite, slate, schist, hornfels, gneiss.
hornfels
296
Which is associated with formation of travertine? cementation, compaction, crystallization, lithification, or deposition
crystallization
297
298
During cementation phase of lithification, which 2 minerals commonly precipitate into spaces between clasts to form cement
-quartz and calcite
299
characteristics of garnet peridotite xenolith
-igneous
-ultramafic
-coarse grained
-peridotite (olivine)
-xenolith means it is foreign
ERTH
flashcards
Decks in class (18)
# Cards
-
erth midterm 1129
-
ANTH midterm 226
-
ERTH midterm 21
-
erth test 3300
-
anth final140
-
lwso final47
-
psyc final148
-
Arky midterm 1250
-
lwso 203 midterm 1 (topic 1-3)175
-
soci midterm 1188
-
lab quiz 460
-
lwso midterm 2 (topic 4-)103
-
arky lab quiz 549
-
lwso midterm 3 extra notes and slide questions68
-
questions that will 100% be on midterm 367
-
arky midterm 2238
-
soci midterm 23
-
arky - rest of stuff for final59
