geology II test 1
magmas that produce __________ igneous rocks contain about 50% silica or less
magic/basaltic
contact metamorphism results whenever
magma is in contact with and bakes colder country rock
what causes magma to rise within the earth
magma is less dense than the surrounding rock
rhyolitic/granitic magma
magma of felsic composition
andesitic magme
magma of intermediate composition
basaltic magma
magma of magic composition
what is magmatic differentiation
magmatic differentiation is the process by which the same magma may produce igneous rocks of different composition
Matthews and Vine found:
magnetic anomalies on the seafloor; magnetic reversals that supported the seafloor spreading hypothesis and tectonic plates hypothesis
which of maths major divisions makes up over 82 percent of our planets volume
mantle
calcite in limestone recrystallizes to form larger interlocking calcite grains. this rock is
marble
which one of the following metamorphic rocks is generally non foliated
marble
metamorphic rocks with the same mineral assemblage belong to the same
metamorphic facies
Dynamic Metamorphism
metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure. exhibits a smeared banded texture
Metamorphism involving the interaction of rocks and minerals with hot reactive fluids in which there is an exchange of ions between the hot reactive fluid and the minerals is termed _______.
metasomatism
schistose
mica or needle shaped minerals are coarse grained and aligned parallel to foliation plate
A metamorphic rock (typically a gneiss) that has undergone partial melting and rapid recrystallization of the felsic-mineral bands to produce a hybrid metamorphic-igneous rock is called
migmatite
the smallest unit of a compound that is still that compound
molecule
what is the name of the volcano which erupted in 1980 in Washington state and caused widespread damage in the washington and oregon region
mount saint helens
laccolith
a mass of igneous rock, typically lens-shaped, that has been intruded between rock strata causing uplift in the shape of a dome.
volcanic breccia
a pyroclastic igneous rock that consists of fragments of volcanic debris, which either fall through the air and accumulate, or form when solidifying lava breaks up during flow
igneous rock
a type of rock that forms from the cooling of molten rock at or below the surface
what is a crater lake
a water-filled collapsed caldera from a cataclysmic volcanic eruption that occurred about 7,700 years ago
shield volcano
a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions
which two minerals are characteristic of lower crystallization temperatures and are absent in basalt and gabbro
muscovite and quartz
gneissic
new minerals separated into light and dark bands , layers, or lenses
are the basalt and gabbros genetically related? in other words, did they both form from the same batch of magma? why or why not?
no, even though both rocks are mafic, the fact that the gabbros had amphibole means it is more evolved than the olivine basalt
cleavage of olivine
none
cleavage of quartz
none
slab
oceanic lithosphere that subjects under a continental plate
the igneous rock peridotite contains mostly the mineral ___
olivine
ferromagnesian silicates (dark in color, mafic)
olivine, pyroxene, amphibole, biotite, magnetite
cleavage of biotite and muscovite
one plane
the most abundant element in earths crust is ____
oxygen
shear force causes mineral to align in
parallel direction to the force
fragmental/pyroclastic
particles blasted apart by explosive eruptions
what type of volcanoes are composed of interbedded lava flows and pyroclastic, usually have snow-capped peaks, and are predominantly found along subduction zones
stratovolcanos
a magma's viscosity is directly related to its _____ content
silica
the most common class of rock-forming minerals is the ______ class
silicate
which of these did wegener use to support his theory of continental drift?
similar rocks and similar fossils on different continents
Protolith: shale, mudstone, siltstone: politic Texture: Dull, earthy luster; excellent rock cleavage (breaks in sheets). Metamorphic Grade: low-grade metamorphism Mineralogy: Microscopic micas (muscovite, biotite, chlorite) Foliation: Slaty Rock Name:
slate
dull, earthy luster, not shiny at all; lowest metamorphic grade, protlith is shale
slate
which of the following list of metamorphic rocks depicts the correct order from least metamorphosed to most metamorphosed?
slate-phyllite-schist-gneiss-migmatite
types of texture in metamorphic rocks
slaty, phyllitic, schistose, gneissic
intrusive, plutonic rocks cool ______ and extrusive, volcanic rock cool
slowly underground, quickly above ground
andean type volcanic arc
some of the magma reaches the surface in the form of continental arc volcanism
if you were to chemically analyze this mineral, where would you find the greatest abundance of sodium
spot B, the edge of the mineral
the process by which pieces of surrounding country rock get dislodged and fall into intruding magma bodies, where they are either remelted or incorporated into the magma as xenoliths, is known as
stoping
which type of volcano is typically found along oceanic-continental subduction zones and continental rift zones
stratovolcano/ composite-cone
which type of volcano produces the most explosive eruption
stratovolcano/ composite-cone
Why is the rim of the Pacific Ocean is called the "Ring of Fire"?
the margins of the pacific ocean are lined almost exclusively with subduction zones and hence the most continuous belt of continental and island arc volcanoes
the energy that powers earths internal processes, such as volcanoes, earthquakes, and mountain building, is supplied by ___
the original heat from earths formation and the decay of radioactive isotopes
ridge push and slab pull
the process in which new material at a ridge or rift pushes older material aside, moving the tectonic plates away from the ridge; the heavy slab pulls more of the plate down
the most important fact affecting the texture of an igneous rock is
the rate of cooling of the magma or lava
hotspots
the surface expression of a mantle plume
doming
-a mountain building process in which magma unable to break through the earth's crust pushes it up -(a) doming is a type of volcanism -(b) doming is a "CONSTRUCTIVE" FORCE
physical properties of a mineral
-color -streak -luster -hardness -specific gravity -crystal habit -fracture or cleavage
a mineral with which of the following silicate structures would dave the highest silica content?
3D or framework silicate structure
What is the net charge of the Si-O tetrahedron?
4-
rift valley
A deep valley that forms where two plates move apart
lava dome
A mountain or hill made from highly viscous lava, which plugs the central conduit of volcanoes
transform boundary
A plate boundary where two plates move past each other in opposite directions
Lithosphere
A rigid layer made up of the uppermost part of the mantle and the crust and makes up the tectonic plates
cinder cone
A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening
inductive reasoning
A type of logic in which generalizations are based on a large number of specific observation; attempts to explain phenomena by looking at their past causes
metamorphic rock
A type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions.
sedimentary rock
A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together or precipitated
composite cone
A volcano composed of both lava flows and pyroclastic material
Who came up with the theory of continental drift?
Alfred Wegener
The image above is a microscope slide of a section of basalt that shows a pyroxene reaction rim surrounding the olivine core. what other mineral would you expect to find in this sample of basalt?
Ca-Plagioclase (maybe)
list the rocks in order of increasing silica content (lowest to highest)
B-E-A basalt, andesite, rhyolite
carbonates
CO3 2-
where would you expect to find the youngest seafloor
D because spreading faster
who developed the seafloor spreading hypothesis
Hess
what was the smoking gun piece of evidence that confirmed the meteorite theory? (Extinction of dinosaurs)
Iridium and shocked quartz at KT boundary
Which statement is true about magma and volcanoes? (Hint: Pay attention to the words in bold)
Low-viscosity, gas-poor magma will flow more readily and easily than high-viscosity magma. Therefore, the eruption will be effusive.
Are the basalt and the gabbro genetically related? In other words, did they both form from the same batch of magma? Why or why not?
No. Even though both rocks are mafic, the fact that the gabbro had amphibole means it is more evolved than the olivine basalt.
common elements
O, Si, Al, Fe, Ca, Na, K, Mg
oxides
O2-, but not bonded to Si, C or S
convergent boundaries
Occur where two plates slide TOWARD each other, commonly forming a subduction zone
Which of the following minerals contains an isolated, or independent, silicate structure (the simplest silicate structure)?
Olivine
decompression melting
Partial melting of hot mantle rock when it moves upward and the pressure is reduced to the extent that the melting point drops, forming magma
Foliated Metamorphic Rocks:Phyllite Protolith: Shale, mudstone, siltstone (politic) Texture: Silky luster, glossy sheen, and wavy surface; good rock cleavage. Metamorphic Grade: low to medium grade, a step up from slate. Mineralogy: Microscopic micas (muscovite, chlorite), but bigger than slate's so as to give the rock its luster. Foliation: Phyllitic Rock Name:
Phyllite
transform boundaries
Places where tectonic plates slide along beside one another as they move
The texture of the igneous rock above can best be described as _______.
Plutonic / Pegmatitic
Deposition
Process in which sediment is laid down in new locations.
Which type of magma, with a silica content of > 65 %, has the greatest tendency to form pyroclastic material and highly explosive eruptions?
Rhyolitic
Sulfides
S2-
Sulfates
SO4 2-
silicates
SiO4 4-
permeability
The ability of a rock or sediment to let fluids pass through its open spaces, or pores.
Gondwanaland
The continents of Africa, South America, India, Australia, and Antarctica when all the continents were a single landmass.
Pumice
igneous rock with froth texture that is felsic to intermediate composition
stratovolcano
The most common volcano. Known for its layers of lava flows and cinder. Built up by violent eruptions that leave the tephra followed by calm eruptions that leave lava flows. They build tall and steep volcanoes.
Subduction
The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.
crustal thickening
The process by which the continental crust increases in thickness, becoming up to 70 km thick (vs. normal thickness of about 35 - 40 km); it can occur during continental collision.
lithification
The process that converts sediments into solid rock by compaction or cementation. ex. sediment into sedimentary rock
subduction zone
The region where oceanic plates sink down into the asthenosphere.
Paleomagnetism
The study of the alignment of magnetic minerals in rock,specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation
mantle wedge
The wedge-shaped area of mantle above a subduction zone where magma is produced.
Calcite fizzes and releases CO2 when exposed to acid
True
Pegmatitic
Very large crystals formed by extremely slow cooling, or in the presence of water
caldera
a large crater caused by the violent explosion of a volcano that collapses into a depression
the main assumption in all the physical science is called _____. This idea states that the laws and principles of nature have been uniform through time. the forces and effects of geologic processes we observe today have been occurring throughout geologic time
actualism
examples of modern continental rifts
afar triple junction caused by the africa super plume
fragmental
all the stuff blown out of an explosive volcanic eruption
examples of failed rifts during the breakup of pangea
amazon river, mississippi river, niger river
lower silica content: pyroxene, plagioclase feldspar= gabbro; higher silica content: k-feldspar, Na-plagioclase feldspar, quartz, small amounts of amphibole, biotite, and muscovite
amount of silica
biotite schism and muscovite schist are metamorphic rocks with a politic (shale) protolith. within which dominant metamorphic facies would you expect to biotite schist and muscovite schist
amphibolite facies
If the partial melt of a gabbro parent rock were to erupt at the surface, the rock that would form would be _______.
andesite
description: intermediate, porphyritic with phenocrysts of plagioclase and pyroxene, grayish groundmass
andesite
if the partial melt of a gabbros parent rock were to erupt at the surface, the rock would form would be
andesite
More Mg present causes ______ to form more frequently
aragonite
decreased mid-ocean ridge activity causes ______ seas
aragonite
icehouse climate makes up mostly ______ seas
aragonite
the oceanic crust is made up of
basalt
which of the following rocks would best record magnetic reversals
basalt
shield volcanoes are composed primarily of _______ and are the worlds ______ volcanoes
basalt, largest
Which of the following lists of magma compositions is the correct order of decreasing (highest to lowest) magma viscosity?
basaltic - andesitic - rhyolitic
Mantle plumes and mid-oceanic ridges both undergo the process of decompression melting to generate magma. Why does mantle peridotite begin to partially melt at a greater depth within mantle plumes than at mid-oceanic ridges?
because mantle plumes originate at the core-mantle boundary and are much hotter than the convective flow at mid-oceanic ridges.
Ferromagnesian minerals (olivine, pyroxene, amphibole, biotite) _______.
belong to a class of minerals called silicates. are composed of independent, single-chain, double-chain, and sheet silicate structures, respectively All the answers are correct. ****** contain iron and magnesium in their chemical composition. are dark in color.
transition zone
below the asthenosphere, upper boundary marked by a sudden increase in density from pressure induced phase transition
tephra
bits of rock or solidified lava dropped from the air during an explosive volcanic eruption; ranges in size from volcanic ash to volcanic bombs and blocks
which of the following metamorphic rocks form in a subduction zone
blue schist and eclogites
according to bowen's reaction series for cooling magma, what minerals is/are likely to form a phenocryst in porphyritic basalt
both olivine and pyroxene
vesicular
bubble holes forze and preserved where gas escaped from the lava
amphibolite is a foliated metamorphic rock composed principally of hornblende and plagioclase feldspar. how might it form
by regional metamorphism of volcanic rocks, such as andesite and basalt
greenhouse climate makes up mostly _______ seas
calcite
increased mid-ocean ridge activity causes _____ seas
calcite
increased and fast mid-oceanic ridge activity results in ___ seas, while decreased mid-oceanic ridge activity results in ____ seas
calcite, aragonite
what is the mineral class for C? (Co3)2-
carbonate
Assimilation
changing a magmas composition by the assimilation of outside matter (ex, more matter can be added to magma by the magma heating up surrounding rock)
diagenesis
chemical, physical, and biological changes that take place after sediments are deposited. low grade burial
Which type of volcano is composed almost exclusively of highly vesicular pyroclastic debris of mafic composition?
cinder cone
in a _____ system, energy can move in and out but matter cannot
closed
phaneritic
coarse grained; all minerals visible to the naked eye
Asymmetry of Overdetermination
collecting trace bits of evidence that indicate an certain event occurred; you don't need to see an actual volcano to know a volcano erupted when you see volcanic ash
rocks that ar subjected to intense heat when they are intruded by magma undergo a process called
contact metamorphism
divergent boundary that forms wishing a continent can develop into which of the following tectonic features
continental rift
andesitic magma lava and andesitic volcanoes are most often associated with a _____ plate boundary
convergent
the magma generated at mid-ocean ridges and hot spots is due to
decompression melting
what process causes the partial melting of mantle peridotite at mid-ocean ridges?
decompression melting
when water is added to mantle peridotite, the melting temperature of mantle peridotite
decreases with depth
granite forms in a
deep intrusive body
if you were to chemically analyze this mineral and the surrounding quenched magma, the spot D (magma) would show it to be ____ in Ca2+
depleted
whenever minerals crystallize and grow within magma, the magma becomes ________ in the elements that compose those minerals and _____ in the elements that remain in the melt
depleted, enriched
which of the following is the best explanation of the process that produced the texture of the metaconglomerate int eh photograph above
deposits in a river system- burial and diagnosis - burial and impact metamorphism flattened and elongated the clasts
porphyritic
describing an igneous rock composed of both large and small crystals
flat, platy micas and elongated minerals will align themselves parallel or sub-parallel to each other in response to
differential force
when stress is applied unequally in different directions, it is termed
differential stress
eroded country rock with an igneous structure sticking out
dike
triple junction
doming of as much as 2-3 km produces a 3-armed rift (Radial fractures)
amphibole is a _____ chain silicate structure
double chain silicate structure
different minerals have unique physical and chemical properties
each mineral has a well-defined chemical composition and a definite crystalline structure
what metamorphic facies exists at a temperature of 600 c and 14 kilobits?
eclogite
in general, magma is composed of
essential all the elements int eh periodic table in various proportions, dissolved gaseous volatiles, minerals that have begun to crystallize in the melt, liquid rock called melt
pyroclastics
exploded from volcano
rocks that solidify from lava flows are typically finer grained than those that crystallize intrusively. why?
extrusive magma cools quickly at the surface, si the mineral grains do not have time to grow large, if at all
Mafic magmas tend to be colder and more viscous than silicic (felsic) magmas.
false
all igneous rocks are composed of minerals
false
because both aragonite and calcite fizz like mad with dilute HCl, the only way to tell them apart is to use X-ray diffraction in order to distinguish their different internal crystalline structures
false
sodium-rich plagioclase crystallizes at higher temperatures than calcium-rich plagioclase
false
the greater the viscosity and volume of gases in a magma, the less likelihood of a violent explosive eruption
false
non-ferromagnesian silicates (light in color, felsic)
feldspars (Ca-plagioclase, K-feldspar), quartz, muscovite
silicates
feldspars, pyroxenes, amphiboles, micas, quartz, clay minerals
what is the chemical composition of obsidian
felsic
as olivine crystals grown in a mafic magma, the magma itself becomes more _____ just due to the fact that the magma is being _______ in Fe and Mg by the growing olivine
felsic, depleted
aphanitic
fine grained; all minerals are microscopic in size
linear lakes
form from the continual stretching in a divergent boundary that forms these lakes and rift valleys
extrusive igneous rocks (volcanic)
formed at earths surface. magma exits or extrudes the subsurface through vents or fissures on the ground, building a volcanic edifice or a plateau
intrusive igneous rocks (plutonic)
formed underground, magma intrudes the surrounding country rock via cracks and faults, or makes its own room by pushing the surrounding ductile rocks aside
trigonal
four axes, three of equal length at 120 degrees from each other. the fourth is either longer or shorter but at a right angle to the other corners
You find a phaneritic igneous rock while hiking. The rock is mainly dark in color. You can't readily identify the black minerals, but you can identify about 30 % Ca-plagioclase and about 17 % olivine. You decide correctly that the rock must be _______.
gabbro
magic, pahneritic, dark in color,
gabbro
volatiles
gaseous components of magma dissolved in the melt. They will readily vaporize at surface pressures
scoria
igneous rock with frothy texture that is of magic composition
Confining pressure at depth _______ melting of dry mantle peridotite and raises its melting temperature.
generates inhibits**** enhances promotes All of the answers are correct.
the continental crust is made up of
granite
which of the following contains the greatest amount of silica
granite
identify the rock above: protolith: granite texture: weakly foliated, minerals are stretched due to ductile shearing MM environment: in a shear zone associated with a large fault system
granite mylonite
Igneous rocks that form from the last minerals to crystallize from magma will have ____ composition consisting of quartz, potassium feldspar, and sodium-rich plagioclase feldspar
granitic (felsic)
the earths geothermal gradient is
greater over volcanic regions
which of the following metamorphic rocks form within the interior of continents as temperature and pressure increase at roughly the same rates
green schist- amphibolite- granulite
aphanitic is also called ____
groundmass
what is the major source of heat for contact metamorphism
heat from a nearby magma body
agents of metamorphism
heat, pressure (stress), chemically active fluids
based on the minerals in granite and the silicate structures of this minerals, granite is a rock with a ____ silica content
high
flood basalt provinces are thought to be the initial expression of
hot spot volcanism
silicate structure (Scroll down)
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjv_sL3pLndAhVMJt8KHfgjAtEQjRx6BAgBEAU&url=https%3A%2F%2Fdarkwing.uoregon.edu%2F~drt%2FClasses%2F201_99%2FRice%2FMinerals.html&psig=AOvVaw1ixE5CvJlyU1s8ly2lZYQL&ust=1536973048484216
Modus Tollens
if just one experiment or prediction fails, then the hypothesis is discarded
confining pressure at depth ____ melting of dry mantle peridotite and raises its melting temperature
inhibits
which of earths major divisions is thought to be the source of earths magnetic field?
inner core
diorite
intermediate, phaneritic
mantle plumes
intra-plate blobs of hotter than normal mantle material that ascend through the mantle. they are not associated with activity at plate margins and are fixed in their location under the lithosphere
which of the following statements concerning isotopes of an element is correct?
isotopes of an element have the same number of protons but different numbers of neutrons
calculate the total volume (m3) of tephra erupted during the eruption
just add the values together
phenocrysts
large crystals
Batholith
large mass of intrusive igneous rock believed to have solidified deep within the earth
The figure above depicts a certain type of lava flow. This type of flow is typically composed of intermediate to rhyolitic magma and plugs volatile escape routes via the vent. This type of lava flow is called _______.
lava dome
the ease with which volatiles can move through a magma is termed ____. the lower the viscosity of the magma, the greater the magma _____. the higher the viscosity of the magma, the lower the magma ___.
permeability
compressive stress will cause minerals to align
perpendicular to the force and parallel to each other
The textural term for the green mineral (olivine) in this rock is _______.
phenocryst
Slightly shiny appearance Crenulated surface Minerals are still too small to be seen with the naked eye.
phyllite
fine grained, silky luster, crinkled surfaces
phyllite
______ is the study of earths systems, , earths materials, changes at the surface and interior of the earth, and the forces that cause those changes
physical geology
Asthenosphere
plasticlike layer below the lithosphere
What term means a large crystal in a finer-grained metamorphic rock?
porphyroblast
during metamorphism, certain non-platy minerals (like garnet, andalusite, kyanite, staurolite) can form very large crystals that are embedded in the mica matrix of the rock
porphyroblasts
lithostatic pressure
pressure exerted on rocks by the weight of overlying rocks
Seafloor Spreading Hypothesis
process by which new seafloor forming at spreading ridges pushes lithospheric plates on the Earth's surface, thus moving continents
regional metamorhism
produces foliated metamorphic rocks, is associated with convergent plate margins and mountain building, produces metamorphic rocks over large areas, and involves differential stress and high temperatures
felsic and frothy rock (white color)
pumice
which of the following minerals contains a single chain silicate structure
pyroxene
contact metamorphism of a sandstone prtolith will result in a rock called
quartzite
sandstones can be baked to form
quartzite
what is the difference between the protolith of marble and the protolith of quartzite
quartzite is made from sandstone, marble is made from limestone
deductive reasoning
reasoning in which a conclusion is reached by stating a general principle and then applying that principle to a specific case (The sun rises every morning; therefore, the sun will rise on Tuesday morning.)
the graph indicates that the addition of water to the system ____ the melting temperature of sodium phosphate
reduces
which of the following causes plate movement
ridge push, slab pull, and convection in the asthenosphere
roof pendant
roof of a magma chamber that has been metamorphosed due to contact metamorphism
Which rock formed from volatile-rich mafic lava?
scoria
magic frothy, red
scoria
peridotite turns into what rock with metasomatism
serpentinite
one mechanism that allows magmatic differentiation is crystal
settling
what type of volcano is the largest, not only on earth but in the solar system
shield volcano
which type of volcano is formed form low-vipocosity basaltic lava flows
shield volcano
which type of volcano would most likely be composed primarily of basaltic lava flows?
shield volcano
the glen fault is a
strike-slip fault
what type of volcano is fueling the volcanoes in the cascade region
subduction zone
fluid flux partial melting of mantle peridotite occurs at which tectonic environment?
subduction zones
what is the mineral class for D (So4)2-
sulfate
divergent boundaries
tectonic plates spreading apart, new crust being formed (ex. mid-ocean ridges, rift valleys).
Bowen's Reaction Series illustrates relations between:
temperature, chemical composition, and mineral structure.
Metamorphic rocks are classified primarily according to _______.
texture - the presence and type of foliation
metamorphic rocks are classified primarily according to
texture- the presence and type of foliation
the image above shows (geothermal gradient graph)
that the average geothermal gradient never intersects the melting curve of dry peridotite, thereby suggesting that no partial melting of the mantle occurs due solely to earths internal temperature
Orthorhombic
three axes, all are unequal in length and at 90 degrees to each other
Stratovolcanoes are intermediate (andesitic) to felsic (rhyolitic) in composition
true
a rock can be vesicular and aphanitic, and vocanic
true
a turbulent mass of dense, hot gas and pyroclastic material flowing down the side of a volcano as a result of either dome collapse or column collapse is know as pyroclastic flow
true
as depicted by the figure above, plate tectonics essentially operates via mantle convection and gravity
true
at divergent plate boundaries, decompression melting generates partial melting of the asthenosphere
true
at divergent plate boundaries, two plates move away from each other as new lithosphere is produced along the rift that develops
true
foliation occurs during high pressure and temperature environments
true
if a volcano experiences a colossal and extremely violent eruption, its edifice and surrounding land may collapse into the partially evacuated magma chamber to form a structure called a caldera
true
in general, water has the effect of lowering the melting temperatures of mantle minerals
true
in the discontinuous branch of bowens reaction series, more complex silicate structures form as the temperature decreases
true
lava tubes are natural conduits, made of cooled and hardened lava, through which fluid basaltic lava flows and is insulated from heat loss
true
most magma begins as partially melted peridotite from the mantle
true
the main differences in the physical properties of aragonite and calcite are hardness, density, and cleavage
true
the two main criteria for identifying igneous rocks are 1)texture and 2) composition
true
to explain continental drift, weaner proposed that the continents broke through the oceanic crust, much as icebreakers through ice
true
unconsolidated (loose) ash and pyroclastic debris deposited on the ground is called tephra
true
ignimbrite
tuff deposited while hot that welds together
cleavage of pyroxene
two 90 degree angles
cleavage of potassium feldspar and plagioclase
two 90 degrees
polymorph
two minerals that have the same chemical composition but a different crystal lattice structure (ex. aragonite and calcite)
cleavage of amphibole
two planes and 60 degrees and 120 degrees
underplating
underneath less-dense continental lithosphere, basaltic magma may pond
which one of the following is not included in the definition of a mineral?
unordered internal chemical structure
Mantle plume model
upwelling mantle plume pushes upward on continental crust, stretching and thinning the crust due to divergent circulation of convective material
fracture zones
vast majority of transform faults occur along segments of oceanic ridges. these breaks are ----
slaty
very fine grained, earth luster, splits easily into thin sheets
frothy
very high magma gas content
pegmatitic
very large minerals
the variety of periodic in the picture above is called unite. Unite is composed almost 100 % of the mineral olivine. based on the silica structure of olivine, the rock unite contains a ______ amount of silica
very low
composed of dome rock fragments, mineral crystals, tiny pumice grains, and glass shards, are collectively called ____
volcanic ash
glassy
volcanic glass; cooled quickly
the addition of _____ to the mantle wedge at subduction zones causes the melting temperature of peridotite to decrease with depth
water
Fluid-flux melting
water reduces the melting temperature of mantle minerals, resulting in partial melting and the production of magma
many scientists rejected continental drift when it was first proposed because
weaner had no mechanism proposed with the theory
igneous rock to sediment
weathering and erosion
magma mixing
when one magma body intrudes into another one
based on hot spot tracks alone, is there any evidence that the direction of movement of the pacific plate has changed in the geologic past? if so, what evidence
yes. the emperor seamount chain shows the pacific plate once moved in a northward direction until about 48 million years ago
which of the following statements apply to the asthenosphere?
zone in the upper mantle that deforms by plastic flow over which tectonic plates move
contact aureole
zone of alteration that forms in the rock surrounding the magma
