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Test 2
Chapters 5-9; LSU Tiffany Roberts
591
Geology
Undergraduate 1
09/18/2012

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Term
Volcano
Definition
An erupting vent through which molten rock surfaces, or a mountain built from magmatic eruptions.
Term
tectonic activity
Definition
Volcanoes are caused by _____
Term
Mount Vesuvius
Definition
In 79 C.E. _____, in Pompeii, Italy, erupted violently causing earthquakes and fine ash and choking fumes to envelope the town, killing nearly 20,000 people & burying the town.
Term
soils
extinguish
climate
Definition
Eruptions can provide highly productive _____ to feed a civilization, _____ a civilization in a matter of minutes, and effect _____.
Term
Lava flows
Pyroclastic debris
Volcanic gases
Definition
The products of volcanic eruptions take three forms. Name them.
Term
Lava flows
Definition
molten rock that moves over the ground
Term
Pyroclastic debris
Definition
fragments blown out of a volcano
Term
Volcanic gases
Definition
vapor and aerosols that exit a volcano
Term
viscosity
Definition
Flow style depends on _____ – which depends on composition, temperature, gas content, and crystal content.
Term
Mafic
Basaltic
Definition
Lava flows with low silica/high Fe and Mg are _____ &_____.
Term
Intermediate
Andesitic
Definition
Lava flows with moderate silica, Fe, Mg are _____&_____.
Term
Silicic
Felsic
Rhyolitic
Definition
Lava flows with high silica/low Fe and Mg are _____,______,&______.
Term
hot
silica
viscosity
Definition
Basaltic (Mafic) lava is very _____, has low _____, and low _____.
Term
thin and fluid
rapidly
long
Definition
Basalt flows are often ______, so they flow ______ and over _____ distances.
Term
Surface texture
Definition
______ reflects the timing of freezing relative to movement.
Term
rapid cooling
cooled crust
insulation
Definition
Lava is able to travel far because _____ of the surface of the lava flow occurs as it emerges to the surface creating a _____, which serves as _____, allowing the hot interior to flow and remain liquid for some distance.
Term
Lava tube
Definition
the insulated, tunnel-like conduit within a flow, through which lava moves
Term
cooling
Definition
Tubes prevent _____, facilitating flow for miles. Tubes eventually will drain and become empty tunnels forming caves and can even transmit water.
Term
Pahoehoe
Definition
a Hawaiian word describing basalt with a glassy, ropy texture
Term
Skin
Definition
Pahoehoe forms when extremely hot basalt forms a _____ that
is rolled into ropy ridges and furrows with flow.
Term
A'a
Definition
a Hawaiian word describing basalt that solidifies with a jagged, sharp, angular texture
Term
cools and thickens
Definition
A’a forms when hot flowing basalt _____.
Term
rubbly deposit
Definition
With flow, lava crumbles into shards and fragments – leaving a _____.
Term
Columnar joints
Definition
solidified flows that contract with vertical fractures that are hexagonal in cross section (create hexagonal columns)
Term
dikes and sills
Definition
Columnar joints typically develop in _____ as flow cools and cracks.
Term
Pillow Basalt
Definition
rounded blobs of basalt that cooled underwater because underwater, basalt cools instantly and cannot flow
Term
glass
Definition
The pillow surface is cracked, quenched _____ (rapid freezing/solidification)
Term
Lava pressure
mid-ocean ridge
Definition
_____ ruptures a pillow to form the next blob. This is common on the _____.
Term
Higher SiO2
rapidly
mound
slowly
Definition
_____ makes andesitic lavas viscous.
Unlike basalt, they do not flow _____. Instead, they _____ around the vent and flow _____.
Term
lumpy
bulbous snout
vent
rubble
Definition
Andesitic lavas are characterized as a _____ flow with a _____ that remain closest to the _____. The outer crust fractures, creating _____.
Term
Rhyolite
coolest
flows
Definition
_____ lava has the highest SiO2 and is the most viscous lava.
It is the _____ and rarely _____.
Term
lava dome
violent eruptions
Definition
Rhyolite lava plugs the vent as a _____, or dome-like mass, which can be blown to smithereens by subsequent ______.
Term
vent
column-like spire or spine
Definition
Sometimes rhyolitic lava freezes while still in the _____, then pushes upward as a _____ (up to 100 m above the vent).
Term
viscosity
temperature
composition
Definition
Characteristics of lava flow depend on the _____, which in turn depends on _____ and _____.
Term
Balsaltic = flow great distances-Pahoehoe and a’a
Andesitic = moderate silica content-More resistant to flow
Rhyolite = highest silica content-Most resistant to flow-Tends to pile into mounds at the vent
Definition
Name the 3 types of lava flows and give a short description of each.
Term
Volcaniclastic deposits
Definition
general term for accumulations of fragmented igneous material
Term
Pyroclastic debris – lava that freezes flying through air
Pre-existing rock fragments (around volcano vent)
Landslide debris
Mudflows
Definition
Name the 4 Types of Volcaniclastic Deposits.
Term
volatiles
bubbles
Definition
Basaltic magma may contain dissolved _____, and as it approaches the surface, it will form _____.
Term
molten magma
Definition
When the volatile bubbles reach the surface, they burst and eject clots and drops of _____ upward to form dramatic fountains.
Term
sizes
Definition
Glass shards and fragmented lava range in _____.
Term
spatter
Definition
Basaltic eruptions generate a lot of _____.
Term
Lapilli
Definition
pea to plum-sized material
Term
Blocks and bombs
Definition
apple to refrigerator-sized basaltic debris
Term
Pele’s Hair (after the Hawaiian goddess of volcanoes)
Definition
strands of glass created by flying lava droplets
Term
Bombs
Definition
streamlined fragments of ejected lava
Term
Intermediate
Felsic
Definition
_____ and _____ magmas erupt explosively.
Term
more
gas
volcanic ash
Definition
Intermediate and felsic lavas are _____ viscous than basaltic magma (from SiO2) and contains more _____. It also produces large quantities of _____ (tiny shards of glass from instantaneous freezing)
Term
Pyroclastic flows (also called nuee ardentes)
Mt. Vesuvius
Definition
an avalanche of hot ash (200– 450°C/ ~390-840°F), pulled down the side of a volcano by gravity. It incinerates everything in its path, immediately killing everything. Give Example.
Term
Tephra
Definition
unconsolidated deposits of pyroclastic grains, regardless of size
Term
Tuff
Definition
lithified ash, or ash mixed with lapilli (formed by burying and transforming into rock)
Term
Air-fall tuff
Definition
accumulations of ash that fell like snow
Term
Ignimbrite (welded tuff)
Definition
sheet of tuff that is deposited while hot; hot pyroclastic flow material; Fuses together while cooling
Term
force
Definition
The _____ of volcanic explosions can fragment and disperse preexisting volcanic rock that has built up around the volcano.
Term
Blocks
Definition
chunks of preexisting rock fragments by eruption; Blown out of a volcanic vent, and piled up nearby. Create unstable slopes that easily fail
Term
10-25%
Definition
Volcanic debris flows result from rain or with the mixing of melting snow and tephra (addition of _____ H2O).
Term
Lahars
Definition
wet slurry/mixture of ash, coarser debris, and water. It is very Deadly because they Move rapidly, up to 50 km/hr and Have consistency of wet cement. A distinct hazard to people living in volcanic valleys.
Term
Water (H2O)
Carbon dioxide (CO2)
Sulfur dioxide (SO2)
Definition
Most magmas contain dissolved gases such as _____, which is the most abundant gas, _____, which is second in abundance, and _____, which produces a rotten egg smell.
Term
Magma composition
Definition
_____ controls gas content.
Term
silica
Definition
Lavas with more_____ contain a greater proportion of gas
Term
Mafic
Definition
_____ magmas tend to consist of a smaller percentage of volatiles
Term
concomitant P drop
Definition
Gases are expelled as magma rises due to _____.
Term
aerosol sulfuric acid (H2S)
Definition
SO2 reacts with H2O to form _____.
Term
Eruption Violence
Definition
Style of gas escape controls _____.
Term
Low viscosity (basalt)
High viscosity (rhyolite)
Definition
_____– Easy escape; mellow eruption
_____ – difficult escape; violent eruption
Term
vesicles
Definition
The last bubbles to form will freeze into the lava and become holes called _____.
Term
lava– felsic and mafic
pyroclastic debris– range in size from ash shards to large blocks
gas– volume relative to magma composition
Definition
Volcanoes erupt _____, _____, and _____. Give a brief explanation of each.
Term
Magma chamber
Fissures and vents
Craters
Calderas
Distinctive profiles
Definition
Volcanoes have characteristic features. Name them.
Term
Shield volcanoes
Cinder cones
Stratovolcanoes
Definition
Name the 3 distinctive profiles of volcanoes.
Term
Magma Chamber
magma
inflate
deflate
Definition
located in the upper crust of a volcano, usually an open cavity or area of highly fractured rock. May contain a large quantity of _____, and may ______ and _____.
Term
intrusive rock
volcano
Definition
Some magma cools in the magma chamber to form _____.
Some magma rises to the surface to form a _____.
Term
vertical pipe
cracks
fissures
Definition
When magma rises to the surface via a conduit, it can be in the shape of a _____, or it can be through ______, called _____.
Term
curtain of fire
Definition
Fissure eruption may display “_____”
Term
discrete vents
Definition
Fissures evolve into _____.
Term
Crater
Definition
bowl-shaped depression atop a volcano that can be up to 500 m across & 200 m deep
Term
material accumulates around the summit vent
the summit collapses into the drained conduit
Definition
Craters develop during eruption as __________________ or just after eruption as ____________________.
Term
Summit eruptions
Definition
located within the summer crater
Term
Flank eruptions
Definition
located along the side of a volcano
Term
Caldera
Definition
big circular depression resulting from a major eruption and the subsequent collapse of the center of a volcano into the large, drained magma chamber below
Term
steep
flat
massive eruptions (sometimes blowing apart nearly the entire volcano)
Definition
Calderas are 1-10 km across, several
hundred meters deep, have _____ sidewalls and _____ floors, form from ____________________.
Term
Crater Lake, Oregon
Definition
Name an example of a caldera in the U.S.
Term
Shield volcanoes
Definition
Broad, slighly domed-shaped (like an inverted shield)
Term
lateral
low-viscosity
low
large
Definition
Shield volcanoes are made by _____ flow of ______ basaltic lava and have a _____ slope and covers a _____ geographic area.
Term
Mauna Loa on Hawaii
Definition
What is an example of a shield volcano in the U.S.?
Term
Cinder Cones
Definition
Conical piles of tephra
Term
smallest
ejected lapilli-sized fragments
vent
repose
symmetrical
Definition
Cinder cones are the _____ type of volcano, built of ________________ piled up at a _____ . Its slopes are at the angle of _____. They are often _____ with a deep summit crater.
Term
Stratovolcanoes (composite volcanoes)
symmetric
landslides
Definition
Large, cone-shaped volcano composed of alternating layers of lava and tephra. Often _____; can be odd shapes due to _____.
Term
Mt. Fuji
Mt. Rainer
Definition
Give an example of a stratovolcano.
Term
Effusive eruptions = produce lava flows
Explosive eruptions = blow up
Definition
Name & give a description of the two dominant eruption styles.
Term
vents
Lava lakes
lava fountains
Low-viscosity basaltic
shield
Definition
In effusive eruptions, lava flows stream away from _____. _____ can form around vent. It can produce huge _____. _____________ lava flow, which yields _____ volcanoes
Term
pyroclastic flows
gas pressure
explosively
Definition
Explosive eruptions produce _____ and they are caused by _____ in the more viscous magma. Pressure is released _____.
Term
stratovolcanoes
calderas
tephra
Andesitic
rhyolitic
Definition
Explosive eruptions create _____. May create _____.
Blanket the landscape with _____. _____ & _____ compositions
Term
Viscosity, Gas Pressure, and Environment
Definition
What controls eruptive style?
Term
Viscosity
Definition
Controls the ease of lava flow.
Term
Low
flows away
High
builds up
Definition
Basalt – _____ viscosity lava _____ from vent.
Felsic – _____ viscosity lava _____ at the vent.
Term
explosive
allows
prevents
Definition
Greater pressure favors _____ style.
Basalt – Low viscosity _____ gas release.
Felsic – High viscosity _____ gas release.
Term
Environment
Subaerial
Submarine
Definition
The _____ where eruption occurs is important. _____ lava flowing on land cools slower than _____ lava which is quickly quenched.
Term
chimney-like conduits
fissures
Definition
Volcanoes erupt from _____ or _____.
Term
shield volcanoes
Definition
Basaltic eruptions yield _____
Term
cinder cones
Definition
Fountaining lava yields _____
Term
stratovolcanoes
Definition
Alternating ash and lava yields _____
Term
composition
Definition
Eruptive style (effusive or explosive) reflects lava _____.
Term
An earthquake triggered a landslide. Subsequently releasing pressure on the magma. A sudden and violent expansion of gases blasted through the side of the volcanoRock, steam, and ash screamed north at the speed of sound. Flattened a forest and everything in it over an area of 600 square km, killing 61 people. Generated lahars, ash fall. Destroyed timber (valued at several 100 million dollars)
Definition
What happened to Mt. St. Helens on May 18, 1980 at 8:32 a.m.?
Term
Plate motion
Definition
_____ is a dominant control on volcanism
Term
mid-ocean ridge (MOR)
Definition
Most lava erupts along the _____.
Term
70%
fissures quenches
continuously active
Pillow mounds
Definition
MOR-generated oceanic crust covers _____ of Earth.
Basalt eruptions from _____ as pillow (lava) and forms volcanoes. MORs are not _____; turns on/off on scales of tens-hundreds of years. _____ are pulled apart with plate motion.
Term
convergent
Definition
Most subaerial volcanoes form at _____ boundaries.
Term
Volatiles
subduction
Definition
_____ from _____ plate initiates melting to produce magma. They release, rise, produce magma, rise, erupt.
Term
Arc volcanoes
Volcanic island arcs
Continental volcanic arcs
Definition
_____ develop on the overriding plate, forming ___ from oceanic crust and _____ from continental crust.
Term
“Ring of Fire”
Definition
Subduction zones border >60% of the Pacific Ocean and form the _____, an over 20,000 km-long chain of volcanoes.
Term
Continental Rifts
mantle (mafic magmas)
crust (felsic magmas)
Definition
_____ yield an array of volcano types due to magma that feeds these types of volcanoes coming from partial melting of the _____ and partial melting of the _____.
Term
Basaltic fissure eruptions – curtains of lava
fountain up
Linear chain of cinder cones
Explosive rhyolitic volcanoes
Stratovolcanoes
Definition
Name the volcano types at continental rifts.
Term
East African Rift
Basin and Range Province
Mid-continent Rift
Definition
Locations of continental rifts are the _____, _____. & _____.
Term
Plumes under oceanic plates
Definition
What makes oceanic hot spots form?
Term
basalt eruptions
pillow lava
island
Definition
Plumes under oceanic plates initiate as _____ at the seafloor forming a growing mound of _____. Over time, volcano builds above sea level to form an _____.
Term
shield volcano
Definition
Once subaerial, basalt lava erupting is no longer freezing so quickly, which allows flows over a greater distance (as a thin sheet). Lava builds upward and outward, and the island grows and yields a _____.
Term
submarine slumps
Definition
Portions of the subaerial volcano can’t resist the pull of gravity and slip seaward, creating large _____.
Term
Continental Hot Spot
Definition
Cuts a continental plate
Term
Yellowstone National Park
Definition
Lies at the NE end of a track of volcanism marked by a string of calderas. It is the oldest caldera at the SW end of track – erupted 16 ma.
Term
basaltic
pyroclastic debris
Definition
Yellowstone's eruptions, unlike Hawaii's, involve both _____ lava and _____.
Term
silica
explosive
Definition
At Yellowstone, basaltic magma rising from asthenosphere heats up and partially melts continental crust (adding _____), which results in _____ eruptions.
Term
Voluminous
fissures
Definition
_____ lava erupts above a plume due to thinned lithosphere erupting magma from long _____.
Term
Flood-basalt
Definition
huge sheets of low-viscosity lava
Term
plateau
Large Igneous Provinces (LIPs)
Definition
Repetitions of eruptions can build up a broad _____, where the aggregate volume of rock can be large (>175,000 km3), yielding ______.
Term
mantle plume
Definition
Flood-basalt eruptions initiate when a _____ first rises beneath a region undergoing rifting.
Term
bulbous head
molten
Definition
In flood-basalt eruptions, the plume reaches the base of the lithosphere- it has a _____ with partially _____ rock.
Term
decompression
fissures
Definition
In flood-basalt eruptions, stretching and thinning of lithosphere allows _____ of plume and even more melting. Melt then rises along _____ formed in the rift – and erupts.
Term
Iceland
Definition
_____ is a hot spot beneath a MOR
Term
plate boundaries
Definition
Most volcanic activity takes place on _____.
Term
divergent
Definition
The sea sort of “hides” _____ plate boundary volcanism (with the exception of Iceland!).
Term
Convergent boundaries-subduction-island & continental arcs
Divergent boundaries-rifting-flood-basalt
No boundary-hot spot-oceanic & continental
Definition
Name the types of volcanism and boundaries.
Term
250,000
Definition
In the past 2,000 years, volcanoes have caused an estimated _____ deaths
Term
Understanding volcanic behavior
Definition
_____ is the best defense against volcanoes.
Term
Lava flows
Pyroclastic flows
Ash and lapilli
Definition
Volcanic hazards due to eruptive materials include _____, _____, & ______.
Term
effusive basaltic
quickly
Definition
Lava threats are mostly from _____ eruptions because it flows _____ and spreads over a broad area. This lava can destroy immovable objects. (lava doesn't typically kill people)
Term
Pyroclastic flows
Instant death
Definition
Nuee ardentes-Clouds of rolling ash and gas race down flanks of a volcano, riding over a carpet of superheated air. _____ to anything in its path.
Term
pyroclastic
pumice
lapilli
Definition
During _____ eruption, ash that erupted in the air will later fall close to the volcano – forming _____ and _____, which can bury everything, smash through things, and stop engines.
Term
lahars
Definition
Addition of water to ash and lapilli results in mudflows called _____.
Term
blast
Definition
Explosions are ejected sideways during a _____.
Term
vertical
Definition
Blast hazard is uncommon because most eruptions are _____.
Term
landslides
Definition
Eruption-related slope failures
Term
common
Definition
Landslides are a _____ occurrence.
Term
concrete
Definition
Lahars have the consistency of _____ and can therefore pack more force and carry away everything in its path.
Term
earthquakes
Definition
Moving magma breaks rocks underground and causes
_____.
Term
small
frequent
Definition
Earthquakes caused by moving magma are _____ in magnitude, tend to be _____, can cause slope failures and damage to structures, and can also induce fires from pipes breaking
Term
Tsunamis
Definition
Where volcanic eruptions occur in the sea, the blast and underwater collapse of a caldera generates _____.
Term
poisonous
Definition
Volcanic gases such as hydrogen sulfide, H2S; carbon dioxide, CO2 are _____.
Term
Recurrence interval
Definition
average time between eruptions
Term
Active
Definition
erupting, recently erupted or likely to erupt
Term
Dormant
Definition
hasn’t erupted in hundreds of thousands of years, but have potential to erupt
Term
Extinct
Definition
not capable of erupting anymore
Term
Tectonics
erosion
Definition
_____ can shut off magma. After extinction, _____ takes over.
Term
historical
age
tectonically
shape
Definition
One can examine _____ record, _____ of erupted rocks, evidence that volcano is still _____ active, and _____ and extent of volcano, which gives information about age in order to determine whether it is active or extinct.
Term
Earthquake activity, heat flow, changes in shape, and emission increases.
Definition
What are the warning signs that precede most eruptions?
Term
seismicity
Definition
magma flow increases _____
Term
floods or lahars
Definition
magma causes volcanoes to “heat up”, which may melt snow or ice, triggering _____ before eruption.
Term
inflate
Definition
magma causes volcanoes to “_____”, causing the surface of the volcano to bulge
Term
gas
Definition
increases in _____ volume indicate magma has entered the ground below
Term
Danger-assessment maps
evacuation
diverting flows
Definition
The government mitigates hazard by using _____, _____, and _____.
Term
climate
Definition
Volcanic eruptions can be large enough to alter _____.
Term
sunlight
solar radiation
infrared radiation
atmospheric cooling
Definition
Ash and aerosols high in the atmosphere block _____ and absorbs incoming _____ during the day; but do not absorb the _____ rising from Earth’s surface at night, causing _____.
Term
Volcanic
Definition
_____ activity is evident on the Moon and other planets.
Term
Lunar maria (dark “seas”)
Definition
are regions of flood basalts from over 3 billion years ago on the moon
Term
Olympus Mons
Definition
extinct Martian shield volcano (largest known in the Solar System)
Term
Mercury
Uranus
Definition
All planets have evidence of volcanism except _____ and _____.
Term
Sedimentary Rocks
Definition
rocks forming at or near the surface of the Earth by cementing (lithifying) loose grains together
Term
weathering
precipitation
shells
shell-producing organisms
Definition
Loose grains are produced from the physical or chemical _____ of preexisting rock, _____ of minerals from water solutions, _____ and their fragments , and growth of masses of _____.
Term
‘veneer’
Definition
Earth is covered by these loose grains as a thin _____ of sediment.
Term
igneous
metamorphic
Definition
Occurring only in the upper portion of the crust, loose grains behave as a “cover” or veneer capping _____ and _____ “basement” rocks.
Term
events
environments
Definition
Layers of sedimentary rock are analogous to pages of a book in that they record information about ancient _____ and _____.
Term
“Sedimentary Record”
Definition
The layers of sedimentary rock that record information are known as the _____.
Term
outcrop
basins
Definition
Sediment cover is thinner (or missing) where igneous and metamorphic rocks _____, and thicker in sedimentary _____, which provide a depression where sediments can accumulate.
Term
sedimentary rocks
Definition
Sediments are the building blocks of _____.
Term
Clastic
Biochemical
Organic
Chemical
Definition
Name the four classes of sedimentary rock.
Term
clastic
Definition
class of sedimentary rock made from weathered fragments (clasts)
Term
Biochemical
Definition
class of sedimentary rock made from cemented shells of organisms
Term
organic
Definition
class of sedimentary rock that contains the carbon-rich remains of plants
Term
chemical
Definition
class of sedimentary rock made from minerals that crystallize (precipitate) directly from water
Term
Clastic
Definition
_____ sed rocks consist of solid grains (clasts) consisting of either individual minerals or fragments of rock stuck together to form a solid mass.
Term
geologic processes
Definition
Clastic sedimentary rocks reflect several _____.
Term
weathering
Definition
generation of detritus (eroded matter) via
rock disintegration
Term
erosion
Definition
removal of sediment grains from rock
Term
Transportation
Definition
dispersal by wind, water, and ice
Term
Deposition
Definition
settling out of the transporting fluid
Term
lithification
Definition
transformation into solid rock
Term
burial
compaction
cementation
Definition
Name the three methods of lithification.
Term
burial
Definition
lithification method where more sediment is added onto previous layers
Term
compaction
Definition
Lithification method where pressure is caused by the weight of overlying material (overburden); reduces pore space by squeezing out trapped water and air.
Term
cementation
Definition
Lithification method where minerals grow in pores (e.g., precipitation from groundwater) and fill spaces – acts like “glue” to hold sediment together.
Term
texture
composition
Definition
Clastic Sed Rocks are classified on the basis of _____ and _____.
Term
Clast (grain) size
Definition
the average diameter of the clasts, ranging from very coarse to very fine (Boulder, cobble, pebbly, sand, silt, clay)
Term
decreases
Definition
With increasing transport, average grain size _____.
Term
Clast composition
Definition
the mineral makeup of sediments (May be individual minerals or rock fragments)
Term
source
environment
Definition
Properties of clast composition and mineral ID provides clues about the _____ of the sediment and the _____ of deposition.
Term
Angularity & sphericity
Definition
indicate degree of transport of clastic sed rocks
Term
detritus
Definition
Fresh _____ is usually angular and non-spherical
Term
increase
Well-rounded
Angular
Definition
Grain roundness (2D) and sphericity (3D) _____ with
transport. _____ = long transport distances. _____ = negligible transport
Term
sorting
Definition
the uniformity of grain size
Term
well-sorted
Definition
uniform grain sizes
Term
poorly-sorted
Definition
wide variety of grain sizes
Term
distance from source
Definition
Sorting becomes better with __________.
Term
cement
Definition
minerals that fill sediment pores when dissolved ions slowly crystallize to fill pores after fluids with dissolved solids flush through the pore system.
Term
weak
strong
Definition
Cement varies from _____ to _____
Term
Common cements
Definition
Quartz, Calcite, Hematite, & Clay minerals are examples of _____.
Term
Coarse clastics
Definition
composed of gravel-sized clasts
Term
Breccia
Conglomerate
Definition
Depending on the roundness & sphericity, coarse clastics may be _____ or _____.
Term
Breccia
Definition
comprised of angular fragments
Term
transport processing
close to
Definition
Angularity of breccia indicates lack of _____, meaning that it was deposited relatively _____ the source.
Term
conglomerate
water transport
Definition
comprised of rounded gravel; Indicates _____.
Term
round angular corners and edges
Definition
Clasts bang together forcefully in flowing water, and collisions __________ of clasts, making conglomerate clast.
Term
some (large) distance
Definition
Conglomerate are deposited _____ from source.
Term
sandstone
Definition
clastic rock made of sand-sized particles (medium to coarse clast sizes)
Term
many
Definition
Sandstone forms in _____ depositional environments/settings
Term
Quartz
Definition
_____ is (*by far) the dominant mineral in sandstones
Term
Arkose
Quartz
Definition
The two varieties of sandstone include _____, which contains abundant feldspar, and _____, which is almost pure quartz.
Term
fine clastics
Definition
composed of silt and clay
Term
siltstone
Definition
Silt-sized particles
Term
shale
Definition
Clay-sized particles
Term
Fine clastics
Definition
_____ are deposited in quieter waters (Floodplains, lagoons, mudflats, deltas, deep-water basins).
Term
petroleum
Definition
Organic-rich shales are the source of _____.
Term
living organisms
Definition
Biochemical and Organic Rocks are sediments derived from _____.
Term
Biochemical
Definition
rock that comes from hard mineral skeletons
Term
organic
Definition
rock that comes from cells of plants, algae, bacteria, and plankton
Term
Biochemical limestone
Definition
CaCO3 skeletal (shell) remains
Term
O2
Definition
Biochemical limestone is found in warm, tropical, shallow, clear, _____-rich marine waters, and contains diverse organisms (plankton, corals, clams, snails, etc.).
Term
Reefs
Shell debris
Lime mud (micrite)
Definition
Many textural varieties of biochemical limestone, including _____, _____, & _____.
Term
biochemical chert
Definition
Rock made of cryptocrystalline quartz
Term
Diatoms
Radiolarians
Definition
Biochemical chert is formed form opalline silica (SiO2) skeleton, made up of _____ (silicon dioxide), or microscopic single-celled algae, and _____(silica).
Term
chert nodules
bed
Definition
Opalline silica added to bottom sediments dissolves, and silica pore fluids solidify to form _____ or _____.
Term
organic rocks
Definition
Made from organic carbon
Term
coal
Definition
altered remains of fossil vegetation (plant remains)
Term
lush tropical wetland
Definition
Coal accumulates in _____ settings.
Term
heat
pressure
carbon
Definition
Coal is formed when remains are deeply buried and _____ and _____ compact material, driving off volatiles (hydrogen, water, CO2, ammonia) and leaving concentration of _____.
Term
Oil shale
Definition
shale with heat altered organic matter
Term
Chemical Sed Rocks
Definition
comprised of minerals precipitated from water solution.
Term
evaporites
Definition
Created from evaporated seawater
Term
deposition
Definition
Evaporation triggers _____ of chemical precipitates.
Term
travertine
Definition
CaCO3 precipitated from groundwater where it reached the surface
Term
calcium (Ca2+)
bicarbonate(HCO3-)
Definition
Travertine is formed when dissolved _____ reacts with _____.
Term
Thermal (hot) springs
Caves
Definition
CO2 expelled into the air causes CaCO3 to precipitate, yielding _____ & _____.
Term
Dolostone
Definition
Limestone altered by Mg-rich fluids (groundwater)
Term
Mg2+ -rich water
Definition
CaCO3 altered to dolomite CaMg(CO3)2 by _____.
Term
limestone
Definition
Dolostone looks like _____, except it has a sugary texture and a pervasive porosity and it weathers to a buff, tan color.
Term
replacement
Definition
Much of dolostone is a limestone that has undergone _____.
Term
Replacement chert
Definition
Nonbiogenic in origin
Term
calcite
Definition
Replacement chert forms when cryptocrystalline quartz replaces _____ crystals in a body of limestone long after the limestone is deposited.
Term
concoidal
Definition
Chert has _____ fracture and can produce very sharp edges.
Term
replacement chert
Definition
Flint, Jasper, petrified wood, and agate are examples of _____.
Term
Flint
Definition
black or grey from organic matter
Term
Jasper
Definition
red or yellow from Fe-oxides
Term
petrified wood
Definition
wood grain preserved by silica
Term
agate
Definition
concentrically layered rings
Term
origin
composition
Definition
Many kinds of sed rocks differ from one another by their mode of _____ and _____ (:Clastic, Biochemical and Organic, Chemical)
Term
sedimentary structures
Definition
Features imparted to sediments at or near deposition.
Term
Layering
Surface features on layers
Arrangement of grains
Definition
Features imparted to sediments at or near deposition include _____, _____, and _____.
Term
deposition
Definition
Sedimentary structures are important for deciphering conditions at or near time of _____.
Term
Sedimentary
Definition
_____ rocks are usually layered or “stratified.”
Term
stratified
Definition
Arranged in planar, close-to-horizontal “beds”
Term
Beds
Definition
single layer of sediment or sedimentary rock with a
recognizable top and bottom
Term
strata
Definition
several beds together
Term
laterally
Definition
Bedding is often _____ continuous for long distances
Term
composition
color
texture
Definition
Beds are often similar in _____, _____, and _____.
Term
deposition
erosion
Definition
Bedding reflects changing conditions during _____ (or _____).
Term
climate
water
velocity
sediment
disturbance
Definition
Changing conditions that are reflected by deposition or erosion include _____, _____ depth, current _____, _____ source, & _____ by organisms.
Term
water depth
current velocity
Definition
_____ and _____ are energy conditions that reflect grain size.
Term
strata
Definition
series of beds
Term
Stratigraphic Formation
Definition
Strata recognized on a regional scale (If more than one rock type must specify “formation”)
Term
formations
Definition
Geologic maps display the distribution of _____ and are named based on their geographic location where they were found.
Term
bedforms
Definition
Water flowing over loose sediment creates _____.
Term
flow velocity
sediment size
Definition
Bedforms are linked to _____ and _____. (E.g., Ripple marks, cross beds, dunes)
Term
ripples
Definition
Cm-scale ridges and troughs that indicate flow (direction, strength).
Term
asymmetric
symmetric
Definition
What are the two types of ripples?
Term
asymmetric ripples
Definition
hint unidirectional flow
Term
symmetric ripples
Definition
hint waveoscillation
Term
sedimentary rocks
Definition
Ripples are often preserved in _____.
Term
dunes
Definition
similar to ripples, but much larger
Term
wind
Definition
Dunes indicate direction of _____ (lee/ slip & stoss sides)
Term
desert
beach
Definition
Dunes form from wind-blown sand in _____ or _____ environments.
Term
internal cross-lamination
Definition
Dunes often preserve large _____.
Term
cross beds
Definition
created by ripple and dune migration
Term
up
piles up
downstream
Definition
Cross beds are formed when sediment moves _____ the gentle side of a ripple or dune and _____, then slips down the steep face of the dune. The slip face continually moves _____, and added sediment forms sloping “cross-bedded” layers.
Term
Underwater “landslides”
Definition
results from loose sediment mixing with water creating a murky, turbulent cloud.
Term
Turbidity current
Definition
moving submarine suspension of sediment that
flows downslope like an underwater avalanche.
Term
Turbidity currents
turbidite
Definition
_____ are caused when sediment moves on a slope as a pulse of turbid water, and as pulse wanes, the water looses velocity and grain settles. The coarsest material settles first, and finest last yielding graded beds. Deposit = _____
Term
Graded beds
Definition
layers of sediment in which grain size varies from coarse at the bottom to fine at the top
Term
Bed-surface markings
Definition
features that occur after deposition while sediment is still soft
Term
Mudcracks
Scourmarks
Fossils
Definition
Bed-surface markings include _____, _____, & _____.
Term
Mud cracks
Definition
polygonal desiccation features in wet mud
Term
wet
dry
Definition
Mud cracks indicate alternating _____ and _____ conditions.
Term
scour marks
Definition
troughs eroded in soft mud by current flow
Term
fossils
Definition
evidence of past life such as footprints or shell impressions
Term
energy
biological
Definition
Depositional environments are locations where sediment accumulates differ in _____ regime, sediment delivery, transport, and depositional conditions, and chemical and physical and _____ characteristics.
Term
terrestrial
marine
Definition
Depositional environments range from _____ to _____.
Term
Terrestrial environments
Definition
deposited above sea level
Term
Red color
Definition
_____ often indicates subaerial conditions because oxygen-rich surface or subsurface water creates oxides iron, or iron oxide.
Term
Marine environments
Definition
deposited at or below sea level
Term
depth
grains
Definition
Marine environments depends on the environment, water _____, and _____ present.
Term
Glacial environments
Definition
due to movement of ice
Term
glacial till
Definition
Glacial ice carries and dumps every grain size (poorly sorted) creating _____, or poorly sorted gravel, sand, silt, clay.
Term
terrestrial
Definition
Glacial, Mountain stream, Alluvial fan, Sand dune, and River,
Lake are all examples of _____ depositional environments.
Term
marine
Definition
Marine delta, Coastal beach, Shallow-marine, Shallow-
water carbonate, and Deep-marine are all examples of _____ depositional environments.
Term
mountain stream
Definition
In _____ terrestrial depositional environments, water carries large clasts during floods. During low flow, these cobble and boulders are immobile.
Term
Course conglomerate
Definition
_____ is characteristic of mountain stream terrestrial depositional environments.
Term
alluvial fans
Definition
sediment that pile up at a mountain front
Term
velocity
conglomerates
arkoses
Definition
In alluvial fans, a rapid drop in stream _____ creates a cone-shaped wedge. Sediments are immature _____ and _____.
Term
sand dunes
Definition
wind blown piles of well-sorted sand
Term
prevailing winds
cross beds
Definition
Dunes move according to the _____ and result in uniform sandstones with gigantic _____.
Term
river beds
Definition
channelized flow transports sediment
Term
channels
Definition
In rivers, sand and gravel fill concave-upward _____, and fine sand, silt, and clay are deposited on nearby floodplains.
Term
lake
Definition
large ponded bodies of water
Term
wetland muds
Definition
In lakes, gravels and sands are trapped near shore, and well-sorted muds deposited in deeper water. They are often capped with _____.
Term
delta
Definition
sediments dropped where a river enters the sea
Term
velocity drops
Definition
In deltas, sediment carried by the river is dumped when _____. Deltas grow over time, building out into the basin, and often develop a topset-foreset-bottomset geometry.
Term
surf zone
Definition
Coastal beaches create a _____.
Term
well-sorted, well-rounded medium sand
Definition
At coastal beaches, sediments are constantly being processed by wave attack, commonly resulting in _______________.
Term
oscillation ripples
Definition
Beach sandstones may preserve _____.
Term
shallow marine
Definition
finer version of beach sediment
Term
siltstones
mudstones
Definition
In a shallow marine, fine silts and muds turn into _____ and _____.
Term
biotic
Definition
Shallow marines usually support an active _____ community.
Term
Shallow water carbonates
Definition
_____ are found in tropical marine deposition environments
Term
invertebrates
carbonate
Definition
Shallow water carbonates contain skeletons of marine _____ born in the _____ factory in warm, clear, shallow, normal salinity, marine waters.
Term
deep marine
Definition
In _____ marine deposition environments, fines predominate far from land sources.
Term
chalk
chert
shale
Definition
In deep marine deposition environments, skeletons of planktonic organisms make _____ or _____, and fine silts and clays turn to _____.
Term
outcrop
Definition
Sediments vary in thickness across Earth’s surface from thin to zero thickness where non-sedimentary rocks _____.
Term
Subsidence
Definition
sinking of land during sedimentation
Term
crustal flexure
faulting
compounded
Definition
Subsidence is due to _____ and _____ and _____ by the weight of added sediments.
Term
sinks
Definition
Thick accumulations of sediment form only in special regions where the surface of the Earth’s lithosphere _____ as sediment collects.
Term
Sedimentary basins
Definition
sediment-filled depression
Term
Basins
Definition
_____ are important locations for natural resources such as coal, petroleum, natural gas, and uranium.
Term
creates space
accommodation space
Definition
Basins form where tectonic activity _____ known as _____.
Term
Different sedimentary basins are distinguished based on the region of the lithosphere plate in which they formed.
Definition
How are different sedimentary basins distinguished?
Term
Rift basins
Passive-margin basins
Intracontinental basins
Foreland basins
Definition
What are the different types of lithosphere regions that sedimentary basins are formed on?
Term
Rift basins
Definition
divergent (pull-apart) plate boundaries
Term
sediment fills the down-dropped basin
Definition
In rift basins, crust thins by stretching and rotational normal faulting, then the thinned crust subsides and ___________________________.
Term
Passive margin basins
Definition
non-plate boundary continental edge
Term
previous rifting
cools
Definition
Passive margin basins are underlain by crust thinned by _____. The thinned crust subsides as it _____.
Term
Intracontinental basins
Definition
interiors far from margins
Term
differential thermal subsidence
Definition
Intracontinental basins result from __________ and may be linked to failed crustal rifts.
Term
Foreland basins
Definition
craton side of collisional mountain belt
Term
loading
Definition
Foreland basins form because flexure of the crust from _____ creates a downwarp that fills with debris that eroded off of the mountains.
Term
Sea-level changes
Definition
__________ strongly influence sedimentary deposition.
Term
Depositional belts
Definition
Changes in sea level are commonplace geologically. _____ shift landward (sea-level rise) or seaward (sea- level fall) in response.
Term
strata
Definition
Layers of _____ record deepening or shallowing upward.
Term
transgression
Definition
flooding due to sea-level rise
Term
landward
upward
Definition
During transgression, sediment belts shift _____; strata “deepen” _____.
Term
regression
Definition
exposure due to sea-level fall
Term
seaward
upward
Definition
During regression, depositional belts shift _____; strata “shallow” _____.
Term
erosion
Definition
Regression is linked to _____ and is therefore less likely to be preserved.
Term
Diagenesis
Definition
physical, chemical, and biological changes to sediment transforming it to sedimentary rock
Term
Bioturbation
Lithification
Dissolution
Mineral precipitation
Definition
Diagenesis can also alter characteristics of sedimentary rock after the rock has formed through _____, _____, _____, _____, & _____.
Term
increases
increases
Definition
During diagenesis, temperature _____ gradually between burial and metamorphism and pressure _____ with burial.
Term
history
Definition
Diagenesis integrates changes across the entire sediment _____.
Term
Metamorphic
Definition
changed from an original “parent rock”
Term
Meta
Definition
change
Term
Morph
Definition
Form/shape
Term
protoliths
Definition
Parent rocks of metamorphic rocks are called “_____”
Term
any protolith
rock cycle
Definition
Metamorphism can occur to _____ because of the _____.
Term
Texture
Mineralogy
Definition
Protoliths undergo “solid-state” changes in _____ & _____.
Term
Temperature
Pressure
Tectonic stresses
Reactions with heated water
Definition
Protoliths undergo "solid state" changes due to changes in _____, _____, _____, & _____.
Term
Unique texture
Unique minerals
Unique foliation
Definition
Metamorphic rocks have distinctive properties, including unique _____, _____, & _____.
Term
Unique texture
Definition
A property of metamorphic rocks where there are intergrown and interlocking grains
Term
Unique minerals
Definition
A property of metamorphic rocks where there are some that are only metamorphic
Term
Unique foliation
Definition
A property of metamorphic rocks where there is a planar fabric from aligned minerals
Term
solid state
Definition
Metamorphic change occurs slowly in the _____.
Term
Recrystallization
Definition
minerals change size and shape (without change in the identity of the mineral constituting the grains).
Term
Phase Change
Definition
new minerals form with the same chemical formula and a different crystal structure (rearrangement of atoms).
Term
Neocrystallization
Definition
new minerals with changes in temperature and pressure
Term
unstable
reactions
Definition
During neocrystallization, initial minerals become _____ and change to new minerals, and the original protolith minerals are digested in _____. Then, elements restructure to form new minerals.
Term
garnet mica schist
Definition
Shale transforms into a _____ through the process of neocrystallization.
Term
Plastic deformation
Definition
mineral grains soften and deform
Term
temperatures
Definition
Plastic deformation requires elevated _____.
Term
plastic
Definition
During plastic deformation, rock is squeezed or sheared and minerals act like _____, changing shape without breaking
Term
Heat
Pressure
Compression and/or shear
Hot water
Definition
Rocks undergo metamorphism when subjected to _____, _____, _____, & _____.
Term
geothermal gradient
magmatic
compression breaks
Definition
When metamorphism occurs as the result of heat, heat energy from the _____, _____ intrusions, or _____ reforms atomic bonds.
Term
Pressure
Definition
_____ increases with depth in the crust.
Term
stability
Definition
Mineral _____ is highly dependent upon temperature and pressure.
Term
phase diagram
minerals
Definition
Mineral stability can be graphed on a “_____.” Changes in T and P lead to changes in _____.
Term
Differential Stress
Definition
Pressure that is greater in one orientation.
Term
tectonic forces
Definition
Differential Stress is a commonplace result of _____.
Term
Normal
Shear
Definition
Two kinds of differential stress are _____ and _____.
Term
Normal Stress
Definition
Stress that operates perpendicular to a surface.
Term
Tension
Definition
Pull-apart normal stress.
Term
Compression
Definition
Push-together normal stress.
Term
Shear Stress
Definition
operates sideways across a surface
Term
smeared out
Definition
Shear Stress causes material to be “_____.”
Term
deforms
Definition
At higher T and P, differential stress _____ rock. (i.e. rocks change shape slowly without breaking)
Term
Equant
Inequant
Definition
Deformation acts on minerals with specific shapes such as _____ & _____.
Term
Equant
Definition
Roughly equal in all dimensions.
Term
Inequant
Definition
Dimensions not the same.
Term
Platy (pancake-like)
Definition
Inequant shape with 1 dimension shorter.
Term
Elongate (cigar-shaped)
Definition
Inequant shape with 1 dimension longer.
Term
align
Definition
Differential stress causes these deformed minerals to _____.
Term
stress trajectory
Definition
Alignment fabric records _____.
Term
foliation
Definition
Preferred platy mineral alignment is called _____.
Term
layered
banded
Definition
Foliation imparts a _____ or _____ appearance.
Term
parallel
Definition
Rocks commonly break _____ to foliation planes.
Term
perpendicular
Definition
Foliation develops _____ to compression.
Term
recrystallize
Definition
During foliation, minerals flatten, ____ and rotate.
Term
Inequant
Definition
_____ grains align by rotation and new growth.
Term
Hydrothermal fluids
Definition
Hot water with dissolved ions and volatiles.
Term
accelerate
alter
Definition
Hydrothermal fluids facilitate metamorphism because they _____ chemical reactions and _____ rocks by adding or subtracting elements.
Term
metasomatism
Definition
Hydrothermal alteration is called _____.
Term
Foliated
Nonfoliated
Definition
Two major subdivisions of metamorphic rocks are _____ & _____.
Term
Foliated
Definition
Metamorphic rock type that has a through-going planar fabric
Term
differential stress
Platy
Definition
Foliated rocks are subjected to _____ and have a significant component of _____ minerals.
Term
composition
grain
foliation
Definition
Foliated rocks are classified by _____, _____ size, and _____ type.
Term
Nonfoliated
Definition
Metamorphic rock type that has no planar fabric evident.
Term
differential stress
equant
Definition
Nonfoliated rock is crystallized without _____. It is comprised of _____ minerals only.
Term
mineral composition
Definition
Nonfoliated rock is classified by _____.
Term
Compositional banding
Definition
Solid state differentiation.
Term
protolith
high-T shearing
Definition
Compositional banding develops in several ways, including original layering in the _____ and extensive _____.
Term
Slate
Definition
Fine clay, low-grade metamorphic shale.
Term
slaty cleavage
Definition
Slate has a distinct foliation called _____.
Term
parallel
Definition
Slate develops by _____ alignment of platy clay minerals.
Term
perpendicular
Definition
Slaty cleavage is oriented _____ to compression.
Term
flat sheets
Definition
Slate breaks along this foliation (slaty cleavage) creating _____.
Term
Phyllite
Definition
Finemica-richrock.
Term
slate
Definition
Phyllite is formed by low- to medium-grade alteration of _____.
Term
Clay
Definition
In Phyllite, _____ minerals neocrystallize into tiny micas
Term
satiny
Definition
Micas reflect a _____ luster.
Term
slate
schist
Definition
Phyllite is between _____ and _____.
Term
schist
Definition
Fine or coarse rock with larger micas.
Term
schistosity
parallel
higher
Definition
Schist has a distinct foliation called _____, where there is _____ alignment of large mica crystals. The micas are visible because they have grown at _____ T.
Term
neocrystallization
Definition
Schist often has other minerals due to _____, such as quartz, feldspars, kyanite, and garnet.
Term
Gneiss
Definition
Has a distinct banded foliation.
Term
felsic
mafic
Definition
Gneiss has light bands of _____ minerals and dark bands of _____ minerals.
Term
Migmatite
Definition
a partially melted gneiss
Term
igneous
metamorphic
Definition
Migmatite has features of ______ and _____ rocks.
Term
lower
higher
Definition
Mineralogy controls behavior of migmatite. Light-colored (felsic) minerals melt at _____ T. • Dark-colored (mafic) minerals melt a _____ T.
Term
Nonfoliated
Definition
_____ rocks lack a planar fabric.
Term
differential stress
equant
Definition
Absence of foliation is possible for several reasons, including rock not being subjected to _____, and dominance of _____ minerals (Which leads to the absence of platy minerals like clays or micas).
Term
Amphibolite
protolith
Definition
Dominated by amphibole minerals; made up of basalt or gabbro _____.
Term
foliated
Definition
Amphibolite is usually not well _____.
Term
Hornfels
Definition
Alteration by heating.
Term
plutonic intrusions
Definition
Hornfels are are associated with _____ and are finely crystalline.
Term
Quartzite
Definition
Almost pure quartz in composition.
Term
quartz sandstone
Definition
Quartzite forms by alteration of _____.
Term
recrystallize
Definition
In quartzite, sand grains in the protolith _____ and fuse.
Term
hard
glassy
resistant
Definition
Like quartz, quartzite is _____, _____, and _____.
Term
Marble
Definition
Coarsely crystalline calcite or dolomite.
Term
protolith
Definition
Marble forms from a limestone or dolostone _____.
Term
recrystallization
Definition
In marble, extensive _____ completely changes the rock, and original textures and fossils in the parent are obliterated.
Term
protolith
Definition
The type of metamorphic rock depends on _____.
Term
quartizite
marble
Definition
Some protoliths yield specific rocks: Quartz SS yields _____ and CaCO3 yields _____.
Term
Metamorphic intensity
Definition
Different minerals are stable as T and P changes
Term
Metamorphic grade
Definition
informal way to indicate the intensity of metamorphism – or the degree of metamorphic change
Term
slight
intense
Definition
A low metamorphic grade indicates _____ temperature and pressure, while a high metamorphic grade indicates _____ temperature and pressure.
Term
prograde
Definition
Metamorphism via increasing T and P (think: burial).
Term
Retrograde
Definition
Metamorphism via decreasing T and P (think: uplift from erosion).
Term
index minerals
Definition
Certain minerals that have a limited P-T range (crystallization & stability); these record metamorphic grade.
Term
metamorphic zone
Definition
regions between of different metamorphic grade.
Term
Geothermal gradient
Differential stresses
Hydrothermal fluids
Definition
Metamorphism occurs in different settings that yield different effects via _____, _____, or _____ (Characteristics governed by tectonics).
Term
thermal
Definition
Metamorphic environment governed by heating by a plutonic intrusion
Term
burial
Definition
Metamorphic environment where there are increases in P and T by deep burial in a basin.
Term
dynamic
Definition
Metamorphic environment where there is shearing in a fault zone
Term
regional
Definition
Metamorphic environment where there is P and T alteration due to orogenesis
Term
hydrothermal
Definition
Metamorphic environment where there is alteration by hot-water leaching
Term
subduction
Definition
Metamorphic environment where there is high P to low T alteration
Term
shock
Definition
Metamorphic environment where there is extremely high P attending a bolide impact
Term
Contact metamorphism
Definition
due to heat from magma invading host rock
Term
host rock
aureole
Definition
Contact metamorphism creates zoned bands (_____) of alteration in _____.
Term
Burial metamorphism
Definition
as sediments are buried in a sedimentary basin, P increases because of the weight of the overburden, and T increases because of the geothermal gradient.
Term
diagenetic
Definition
Burial metamorphism requires burial below _____ effects.
Term
Dynamic metamorphism
Definition
Breakage of rock by shearing at a fault zone (*shearing alone; not T or P).
Term
brittle
breccia
Definition
Fault location determines type of alteration. In shallow crust (Upper 10–15 km) rocks behave in a _____
fashion, and mineral grains crush-forming fault _____.
Term
ductile
mylonite
Definition
In deeper crust (Below 10–15 km) rocks behave in a _____ manner. Minerals smear like taffy to form _____ (which are found at all plate boundaries)
Term
regional metamorphism
Definition
Tectonic collisions deform huge “mobile belts.”
Term
compression
Definition
During regional metamorphism, directed _____ thickens mountains.
Term
heated
squeezed
smashed
Definition
Rocks caught up in mountain building during regional metamorphism are _____ via the geothermal gradient and plutonic intrusions, _____ and heated by deep burial, and _____ and sheared by differential stresses.
Term
regional metamorphism
Definition
most important in terms of amount of rock
altered.
Term
foliated
Definition
Regional metamorphism creates _____ rocks
Term
Collisional belts
Definition
_____ resulting form regional metamorphism are often thousands of km long and hundreds of km wide
Term
hydrothermal metamorphism
Definition
alteration by hot, chemically aggressive water.
Term
MOR magmas
black smokers
Definition
Hydrothermal metamorphism is a dominant process near _____, where cold ocean water seeps into fractured crust and is heated by magma, then reacts with mafic rock, and the hot water rises and is ejected via _____
Term
subduction metamorphism
Definition
subduction creates the unique blueschist facies
Term
Trenches
accretionary prisms
Definition
_____ and _____ have a low geothermal gradient (low T) and a high pressure.
Term
glaucophane
Definition
Where there is subduction metamorphism, there is high P, and low T, which favors _____, a blue amphibole mineral
Term
shack metamorphism
Definition
the rare occasion when Earth is struck by a comet or an asteroid.
Term
high-pressure minerals
Definition
During shock metamorphism, impact generates a compressional shock wave, creating extremely high P, and heat that vaporizes or melts large masses of rock, which creates _____.
Term
Exhumation is due to uplift, collapse, and erosion
Definition
How do metamorphic rocks return to the surface?
Term
shields
Definition
Large regions of ancient (Precambrian, >500 mya) high-grade rocks, called _____, are exposed in continental interiors.
Term
orogenic belts
Definition
Shields are eroded remnants of _____.
Term
sedimentary cover
Definition
Shield rocks form the basement under _____.
Term
3.5 million
Definition
Earthquakes have caused _____ deaths in the last 2000 years.
Term
earthquake
Definition
earth shaking caused by a rapid release of energy
Term
waves
Definition
During an earthquake, energy moves outward as an expanding sphere of _____ that can be measured around the globe.
Term
Tectonic stresses that cause rocks to break.
Definition
What causes earthquakes?
Term
seismicity
Definition
Earthquake activity
Term
motion
fault
mineral
inflation
eruption
landslides
meteorite
nuclear
Definition
Seismicity occurs due to _____ along a newly formed crustal fracture (or fault), motion on an existing _____, a sudden change in _____ structure, _____ of a magma chamber, volcanic _____, giant _____, _____ impacts, or _____ detonations.
Term
Hypocenter
Definition
“focus”, spot within the Earth where earthquake waves originate
Term
fault surface
Definition
Hypocenters usually occur on a _____.
Term
outward
Definition
Earthquake waves expand _____ from hypocenter.
Term
Epicenter
Definition
land surface above the hypocenter
Term
faults
Definition
Majority of quakes occur along _____.
Term
faults
Definition
Common crustal fractures that move rock masses.
Term
displacement
Definition
The amount of movement along a fault is called _____, or an offset or slip.
Term
Markers
Definition
_____ reveal the amount of offset.
Term
planar
Definition
Faults are like _____ breaks in blocks of crust
Term
slope
Definition
Most faults _____ (some are vertical)
Term
Footwall
Hanging wall
Fault Scarp
Definition
On the sloping fault, crustal blocks are classified as a _____, or block below the fault, a _____, or block above the fault, or a _____, which is the difference in displaced ground elevation (small step)
Term
relative
Definition
Fault type based on _____ block motion.
Term
normal fault
Definition
hanging wall moves down relative to footwall
Term
extension-stretching
Definition
Normal faults result from _____.
Term
Reverse fault
Definition
hanging wall moves up relative to footwall
Term
compression – squeezing or shortening
steep
Definition
Reverse faults result from __________. The slope (dip) of fault is _____.
Term
Thrust fault
Definition
special kind of reverse fault (hanging wall moves up relative to footwall)
Term
not steep
Definition
The slope (dip) of a thrust fault surface is _____.
Term
Strike-slip fault
Definition
blocks slide laterally past one another
Term
motion
vertical
Definition
On a strike-slip fault, there is NO vertical block _____, the fault surface is nearly _____.
Term
Quakes occur when rocks break and a new fault forms. Quakes occur when a preexisting fault suddenly slips
again.
Definition
What is the relationship between faulting and earthquakes?
Term
stress
stick-slip behavior
Definition
A preexisting fault may suddenly slip again due to _____ (push, pull, or shear) or _____, where there is alternation between stress build-up at a fault (no slip) and the release of stress (slip – earthquake).
Term
Tectonic
elastic strain
Definition
_____ forces add stress to unbroken rocks, and the rock deforms slightly, which is called _____.
Term
cracks
failure
brittle deformation
Definition
Continued stress from unbroken rocks will cause growth of _____. Eventually, cracks grow to the point of _____.
When the rock breaks, elastic strain transforms into _____, releasing earthquake energy.
Term
jumps
friction
stick-slip
Definition
Faults move in _____. Once movement starts, it quickly stops due to _____. Eventually, strain builds up again causing failure. This is the _____ behavior.
Term
Elastic Rebound Theory
Definition
refers to the concept that earthquakes happen because of stresses built up, causing rocks to bend elastically until slip on a fault occurs
Term
boundary
Definition
The Elastic Rebound Theory relates the movement of one plate with respect to another, along the plate _____, generating the stress to generate an earthquake.
Term
Seismic waves
Definition
energy from rock/sediment displacement
Term
where
how
Definition
Waves are distinguished on the basis of _____ and _____ the waves move.
Term
body waves
Definition
waves that pass through Earth’s interior
Term
surface waves
Definition
waves that travel along Earth’s surface
Term
primary (P)
parallel
Definition
Compressional, or _____ waves exhibit push-pull (compress and expand) motion. Vibrations are _____ to the direction of wave. They travel through solids, liquids, and gases, and travel the fastest.
Term
secondary (S)
perpendicular
solids
Definition
Shear, or _____ waves exhibit “shaking" motion. Vibration direction is _____ to wave direction. They travel only through _____, and are slower.
Term
love (L) waves
Definition
S waves intersecting the surface that move back and forth like a writhing snake.
Term
Rayleigh (R) waves
Definition
P waves intersecting the surface that move like ripples on a pond.
Term
destructive
Definition
L & R waves are the slowest and most _____.
Term
foreshocks
Definition
smaller earthquakes proceeding the “main shock”
Term
smaller
major
Definition
With foreshocks there are _____ cracks eventually linking up to form a _____ rupture.
Term
aftershocks
Definition
smaller earthquakes occurring after the “main shock” for days to several weeks
Term
stresses
Definition
With aftershocks, there is movement of rock during the main quake generating new _____, still large enough to generate small nearby faults.
Term
seismology
Definition
study of earthquake waves
Term
seismographs
Definition
Instruments that record seismicity
Term
size
location
Definition
Seismology reveals _____ and _____ of earthquakes anywhere on earth using seismographs located worldwide.
Term
arrivals
motion
Definition
Seismographs measure wave _____ and magnitude of _____.
Term
sink
Definition
Seismographs are bolted to bedrock in protected shelter. The 1st wave of activity causes seismograph frame to _____, and the pen goes up, and the next vibration causes opposite motion.
Term
P
S
Surface (R & L)
Definition
Waves always arrive in sequence. The _____ waves first, _____ waves second, _____ waves last.
Term
velocities
distance
travel-time
Definition
One may locate an epicenter because p and s waves travel at different _____. The first arrivals of p and s waves vary with _____. A _____ graph plots the distance of each station to the epicenter.
Term
radius
Definition
Data from 3 stations can pinpoint the epicenter by drawing a circle around each station. The _____ is equal to the distance to epicenter, therefore, circles around stations will intersect at the epicenter.
Term
intensity
magnitude
Definition
Earthquake size is described by either _____ or _____.
Term
Mercalli intensity
Definition
The degree of shaking damage can be measured on a _____ scale, where roman numerals are assigned to different levels of damage (I, lowest to XII, highest).
Term
zones
diminish
Definition
Damage occurs to humans and human-made
structures in _____, and _____ in intensity with
distance.
Term
magnitude
Definition
The amount of energy released by an earthquake.
Term
maximum
normalized
Definition
Magnitude is the _____ seismogram motion and is _____ for distance.
Term
richter
Definition
best magnitude scale for shallow quakes
Term
moment
Definition
scale that considers different waves, area of fault, and amount of slip
Term
logarithmic
Definition
Magnitude scales are _____, meaning for increases of 1 unit there is a 10 fold increase in ground motion.
Term
32
Definition
Earthquake energy can be calculated, and is related to magnitude. If it increases by 1 in magnitude, there is a _____-fold increase in energy.
Term
100,000
Definition
Small earthquakes are frequent. There are about _____ magnitude 3 earthquakes per year.
Term
32
Definition
Large earthquakes are rare. There are about _____ magnitude 7 earthquakes per year.
Term
shallow
Definition
_____ earthquakes are located at divergent and transform boundaries.
Term
intermediate
deep
Definition
_____ & _____ earthquakes are located at convergent boundaries.
Term
MOR
transform
trenches
continental
Definition
Shallow (0-20 km) earthquakes occur along _____, _____ boundaries, the shallow part of _____, and on _____ crust.
Term
subduction
Benioff-Wadati
Definition
Intermediate (20-300 km) and deep (300-670 km) occur along the _____ trace, or the _____ zone.
Term
stresses
slap pull
Definition
Intermediate and deep earthquakes occur due to _____ by
shear between plate and mantle; and _____ of deeper part of plate.
Term
convergent
Definition
Earthquakes occur along _____ boundaries, and it is for this reason that cities near subduction zones have frequent earthquakes. Most are minor, but periodically, they are devastating.
Term
transform
rifts
collision
intraplate
Definition
Continental crust earthquakes occur along continental _____ faults (San Andreas), continental _____ (Basin and Range, East African Rift), _____ zones (Himalayas, Alps), or _____ settings (ancient crustal weaknesses).
Term
5
Definition
_____% of earthquakes are intraplate earthquakes. No one really knows why these happen.
Term
ground shaking
displacement
Definition
Earthquake hazards such as _____ and _____ occur because waves arrive in a distinct sequence, and different waves cause different motion.
Term
rapid up and down
Definition
P waves, the 1st to arrive, produce a _______________ motion.
Term
back and forth
damage
Definition
S waves, the 2nd to arrive, produce a pronounced _____ motion, usually much stronger than from P- waves. It is for this reason that S waves cause extensive _____.
Term
writhe like a snake
Definition
Surface waves lag behind S waves. The Love waves are the first to follow. These make the ground ___________.
Term
ripples in a pond
Definition
R waves are the last to arrive. They make the land surface behave like _____. These waves may last longer than others, and for this reason may also cause extensive damage.
Term
magnitude
distance
intensity
duration
subsurface
Definition
Severity of shaking and damage depends on the _____ (energy) of the earthquake (More = more), the _____ from the hypocenter, the _____ and _____ of the vibrations, and the nature of the _____ material.
Term
Bedrock
Definition
_____ transmits waves quickly, causing less damage.
Term
Sediments
Definition
_____ bounce waves, causing amplified damage.
Term
landslides
avalanches
Definition
Shaking causes slopes to fail, causing _____ & _____.
Term
failures
Definition
Hazardous slopes bear evidence of ancient slope _____.
Term
Rockslides
avalanches
Mount St. Helens
Definition
_____ and _____ follow earthquakes in uplands.
(_____ erupted via an earthquake landslide.)
Term
liquefaction
Definition
Waves liquefy H2O-filled sediments
Term
pore pressures
slurry
Definition
During liquefaction, high _____ force grains apart, reducing friction. Liquefied sediments flow as a _____. Sand becomes “quicksand;” clay becomes “quickclay.”
Term
Fire
Definition
_____ is a common hazard following earthquakes because shaking topples stoves, candles, and power lines, and broken gas mains and fuel tanks ignite.
Term
Tsunamis
Definition
Earthquakes can cause _____, or seismic sea waves (not tidal waves).
Term
drops
raises
Definition
Tsunamis occur when normal faulting _____ the seabed and thrusting _____ it, displacing the entire volume of overlying water. Then, a giant mound (or trough) forms on the sea surface, and feature collapse creates waves that race rapidly away.
Term
upper 100 meters
entire depth
Definition
Wind waves influence the _____ of water, while tsunami waves influence the _____ of water.
Term
meters
kilometers
Definition
Wind waves have wavelengths of several tens to hundreds of _____, while tsunami waves have wavelengths of several 10s to 100s of _____.
Term
related to
unaffected by
Definition
Wind wave height and wavelength are _____ windspeed, while tsunami wave height and wavelength are _____ windspeed.
Term
tens
100s
Definition
Wind wave velocity maximum is several _____ of km per hour, while tsunami wave velocity maximum is several _____ of kph.
Term
Wind
tsunami
Definition
_____ waves break in shallow water and expend all stored energy, while _____ waves come ashore as a raised plateau of water that pours onto the land.
Term
jetliner
Definition
Tsunamis race at _____ speed across the ocean.
Term
wave height
wavelength
Definition
Tsunamis may be almost unnoticeable in deep water because of their low _____ (amplitude) and long _____ (frequency).
Term
depth
speed
celerity
Definition
Relationship between water _____, wave _____, and wave _____ causes the wave height to grow in shallow water, and may reach 10-15 m or more.
Term
bathymetry
topography
Definition
Tsunami destruction of the coast depends upon offshore _____ and the _____ of shore.
Term
amplitude
energy
Definition
Offshore broad shallows increase _____ but sap wave _____.
Term
Quick deep-to-shallow transition
Definition
_______________ is the deadliest condition because waves have maximum energy, wave heights are modest, and water pours onto land as a sheet.
Term
maximum
less
Definition
Broad lowland where the wave hits shore results in _____ damage, while the steep rise of land results in _____ damage.
Term
scarce
disabled
hospitals
overtaxed
corpses
Definition
Disease is a prominent earthquake hazard because food, water, and medicines are _____, basic sanitation capabilities are _____, _____ are damaged or destroyed, health professionals are _____, and there may be many decaying _____.
Term
long-term
Definition
Prediction would help reduce catastrophic losses, but they can only be predicted _____ (tens to hundreds of years); they CANNOT be predicted short-term (hours to months).
Term
seismic zones
Definition
Long-term prediction determine the probability of a certain magnitude earthquake occurring on a timescale of 30 to 100 years, or more, in _____.
Term
repetitive
Definition
Long-term earthquake predictions are based on the premise that earthquakes are _____. Geologists map historical epicenters and ancient earthquakes.
Term
sand
strata
radiometric
Definition
Geologic evidence of earthquakes are _____ volcanoes, offset _____, and _____ dating of tree rings.
Term
location
magnitude
Definition
The goal of short-term predictions is to determine the _____ and _____ of a large earthquake.
Term
foreshocks
strain
stress
Definition
Earthquakes do have precursors, including clustered _____, crustal _____, and _____ triggering.
Term
mapping
construction codes
regulating
Definition
We can prepare for an earthquake by understanding what happens during one, by _____ active faults and areas that are likely to liquify from shaking, developing _____to reduce building failures, and _____ land-use to control development.
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