Geology Ch. 4-5, Geology: Overview of the Physical Earth, Bowens Reaction Series, Rocks, Quiz Questions
A geologist finds an igneous rock consisting of microscopic mineral grains of olivine, pyroxene, and plagioclase. This rock...
a) probrably cooled quickly b) would probably be named a basalt
proto star
a star that is almost a star, a big lump of hydrogen/helium, not a star just yet
Felsic magmas tend to have the lowest viscosity because of their...
none of these are correct, felsic magmas have the highest viscosity
solar bodies
objects seen in our own solar system. (asteroids)
oceanic-continental convergence
oceanic lithosphere will always subduct below the continental lithosphere, caused by the density difference between the oceanic (3.0 g/cm3) and continental (2.7 g/cm3) lithosphere, oceanic plate melts and turns into hot magma which burns its way through the continental plate → creating a volcano and causing many earthquakes
Volcanic arcs are often formed at these plate boundaries
oceanic-continental convergent boundaries
Three types of convergent plate boundaries
oceanic-continental, oceanic-oceanic, continental-continental
Early in the history of the solar system, our sun eventually became hot enough to give off light because...
of nuclear fusion in the core. The Earth is hot, in part, because of radioactive elements in the crust and mantle. The sun is hot due to collisions that turn hydrogen into helium (nuclear fusion).
The interior of the Earth is extremely hot because...
of radioactive elements in the crust and mantle. Earths interior is hot for a number of reasons -but nuclear fusion in the core is not one of them. Only stars are large enough to have nuclear fusion processes at work.
valence shell
outermost electron shell
Earth's crust is made of
oxygen, silicon, and aluminum
noble gases
perfectly ok by themselves, meaning their electrically neutral
The asthenosphere is made of
peridotite, which is mafic
Fractional Crystallization
since each mineral begins to crystallize at different temperature, if these minerals are removed from the magma liquid the liquid composition will change; can change a mafic magma into a felsic magma; crystals can be removed by sinking or by floating depending on density
nebulae
space dust containing hydrogen/helium
During decompression melting of the mantle beneath a mid-ocean ridge...
the magma that forms has more silica than the rock that melts
The inner planets are much smaller than the outer planets because...
they formed inside the "frost" line. Radiation from the sun, coupled with solar wind (particles emitted by the sun), drove lighter gases like hydrogen and helium into the outer parts of the solar system.
cosmic bodies
things seen beyond the solar system (stars, galaxies)
What makes up a galaxy?
cosmic bodies, solar bodies, black holes, nebulae
Why is the Earth's core not a source of magma?
* Need definition
Large explosive caldera like the one at Yellowstone National Park...
-are more common above felsic magma chambers - have the potential to modify global climate if they erupt large volumes of sulfur into the atmosphere
Magma
created by melting of rocks
For something to be classified as a mineral it must...
-be solid -have regular repeating geometry of atoms
Why is our planet warm?
-heated collisions -radioactive decay
Transform plate boundaries...
-might connect two offset mid ocean ridges -might connect two offset subduction zones -might connect the tip of a mid ocean ridge with the tip of a subduction zone
The outer planets
-mostly hydrogen and helium -formed in a collapsing nebula that also formed our sun
As mafic magmas rise towards the Earth surface and cool...
-olivine would grow first, causing the remaining magma to be enriched in silica - the magma could become intermediate in composition over long periods of time
Oceanic crust...
-tends to be much younger than continental crust -has less silica than continental crust
Which of the following are true of Earth's interior?
-the amount of iron increases from the crust to the core -the amount of oxygen increases from the core to the crust
The Doppler Effect ...
1) explains why a car horn moving toward you would sound higher pitched than one moving away from you 2) states that sound waves from a car horn are compressed in front of the moving car
The Big Bang Theory can be used to explain
1)Red Shift 2)Cosmic Background Radiation
The Big Bang Theory ...
1)explains how the universe formed 2)explains why distant stars and galaxies appear to be moving away from Earth
Groups of Silicate Minerals
1. Dark (ferromagnesian) Silicates 2.light (nonferromagnesian) silicates Light silicates have more silica than dark silicates
Circumstances under which magma formation occurs
1. Decompression: during convection the hot mantle rises to lower pressure or depth and carries its heat with it; melting occurs at progressively higher temperatures with increased depth 2. Addition of Water: water causes rocks to melt at a lower temperature; generates magma at convergent plate boundaries where cool slabs of oceanic lithosphere descend into the mantle (subduction zones) 3. Transfer of Heat: magmas that were generated by some other mechanism intrude into cold crust they bring the heat with them; repeated intrusions can transfer enough heat to increase the local geothermal gradient and cause melting of the surrounding rock
What are the different types of plate tectonic boundaries?
1. Divergent 2. Convergent 3. Transform
Types of Textures
1. Glassy Texture (Obsidian) 2. Porphyritic Texture (2 different crystal sizes) 3. Phaneritic (coarse grained): you can see mineral grains without a microscope 4. Vesicular texture: extrusive rock containing voids left by gas bubbles that escape as lava solidifies (Pumice) 5. Pyroclastic (fragmental): fragments that consolidate that were ejected during an explosive volcanic eruption 6. Aphanitic (fine-grained): crystals that are too small for the individual eye to see; need a polarizing microscope
Steps of the Rock Cycyle
1. Igneous Rocks undergo weathering/erosion 2. they form sediments 3. lithification occurs 4. sedimentary rocks are formed 5. metamorphism occurs and metamorphic rock is formed
Signs of Volcanic Eruption
1. Increased seismic activity 2. Ground bulge upward 3. escape of volcanic gases 4. increased surface temperature because of heat from magma may result to hydrothermal springs activity or melting snow
Why Should we study Volcanoes
1. Lava flows build up volcanic islands like hawaii; Creates new land 2. Geothermal energy: underground heat is generated by igneous activity 3. effect on climate: very large eruptions can result in measurable global cooling resulting in crop failures and famines
Types of Magma
1. Mafic/Basaltic: Low in silica content, low viscosity (thin/runny), higher temperature 2. Intermediate/Andesitic: medium level of silica content, intermediate viscosity, medium temperature 3. Felsic/Granitic: high silica content, high viscosity (thick/slow) lower temperature
Magma formation in relation to plate tectonics
1. Mid Ocean Ridge: main process for magma formation is compression; at divergent boundaries basalt and gabbro are commonly formed 2. Convergent Boundaries: water addition; Andesite comes from partial melting of oceanic crust; Granite comes from partial melting of lower continental crust 3. Intraplate Igneous Activity: rising mantle plumes produce localized hotspots and volcanoes when they produce magmas that rise through oceanic/continental crust (Hawaii); mafic igneous rock usually formed at hotspots (basalt) 4.
Types of Volcanic Eruptions
1. Quiescent eruptions: calm oozing of magma out of the ground produces lava flows. Usually associated with basaltic lavas of low viscosity 2. Explosive eruptions: produces rapidly cooled rock fragments called pyroclasts, size ranges from dust (ash) to boulders (blocks and volcanic bombs) Usually associated with felsic lava of higher viscosity
Determinants of Viscosity
1. Temperature: the hotter the lava, the lower the viscosity; the cooler the lava the higher the viscosity 2. Composition (silica content): the more mafic the lava (less silica) the lower the viscosity; the more felsic the lava (more silica) the higher the viscosity. 3. Volatile content (gases dissolved in the lava): lava may contain up to 6% or more of their masses as gases; the two most abundant gases in lava are water vapor and carbon dioxide; there is also nitrogen, sulfur dioxide and carbon dioxide; the HIGHER the volatile content the LOWER the viscosity; the LOWER the volatile content the HIGHER the viscosity.
Igneous Rocks Chemical Composition
1. Ultramafic (less than 45% silica) composed entirely of dark colored ferromagnesian minerals 2. mafic rocks (45-50% silica) contain dark colored minerals that are abundant in iron, magnesium, calcium 3. Intermediate rocks (50-65% silica) contents b/w mafic and felsic 4. felsic (silicic rocks greater than 65% silica) contain light colored minerals abundant in silica, aluminum, sodium, and potassium
Plate tectonics and Volcanism
1. Volcanic activity at divergent boundaries (mid ocean ridges) b/c of decompression melting; causes eruption of basaltic magmas and pillow lavas; forms most of the sea floor 2. Volcanic activity at convergent boundaries results in most well known composite volcanoes with viscous andesitic lavas 3. Within plate volcanic activity- mantle plumes (hot spots) result in basaltic magmas/lavas
How do we classify pyroclastics?
1. Volcanic bombs 2. Volcanic ash
Magma components
1. liquid portion (melt): composed mainly of mobile ions from common elements in the earth's crust 2. solids (if any): crystals of silicate minerals; "crystalline mush" 3. Volatiles (gaseous component): dissolved gases in the melt that vaporize at surface pressure and may propel the magma from the vent
Magma types
1. mafic magmas: will crystallize into basalt or gabbro if early formed minerals are not removed 2. intermediate magmas: will crystallize into diorite or andesite if minerals are not removed 3. felsic magmas: will crystallize into granite or rhyolite if separation of early formed ferromagnesian minerals increases silica content
characteristics of magma
1. magmas parent material is igneous rocks 2. magma is formed by partial melting in the earth's crust 3. magma at the surface is called lava
Factors influencing igneous rock texture
1. the rate at which molten rock cools 2. the amount of silica present in the magma 3. the amount of dissolved gases in the magma
Silica enrichment
1..Olivine grows as the magma cools 2. Remaining magma becomes enriched in silica 3. The remaining magma rosters through the crust, continuing to cool off 4. Silica enrichment continues to occur as minerals grow
According to astronomers, the universe is approximately...
13-14 billion years old
Earth's physical make up
30% Oxygen 35% Iron 15% Silicon 13% Magnesium
oceanic crust
7km, much thinner than the continental crust, rocks in the oceanic crust have much less silica, but more iron and magnesium present. Has the composition of basalt. (-50% silica). Younger rocks.
High temperature feldspar
Calcium rich
Lahar
A destructive mudflow of pyroclastic material on the slopes of a volcanoes. Mixtures of ash and water that can flow at excess speeds.
Plagioclase Feldspar
A feldspar containing sodium and/or calcium in addition to aluminum, silicon, and oxygen.
Volcanic necks
A long string of dykes that lead up to a volcanic neck source
Melt Viscosity
A measurement of resistance to flow
Nebular Theory
A model for the origin of the solar system that supposes a rotating nebula of dust and gases that contracted to form the Sun and planets.
divergent boundary
A plate boundary where two plates move away from each other.
convergent boundary
A plate boundary where two plates move toward each other.
Vesicular Basalt
A porous rock formed by solidified lava with trapped bubbles. Igneous
The East African Rift
Active divergent boundary located in Africa, adding more land and, therefore, increasing its size
crystallization
A process that reverses the events of melting; the temperature of the liquid drops and the ion rate of movement slows so they pack closer together and silicon oxygen tetrahedra's are formed
Lithosphere
A rigid layer made up of the uppermost part of the mantle and the crust.
Red shift
A shift toward longer wavelengths of the spectral lines emitted by a celestial object that is caused by the object moving away from the earth.
cinder cone volcano
A small, steeply sloped volcano that forms from moderately explosive eruptions of pyroclastic material.
island arc
A string of volcanoes that form as the result of subduction of one oceanic plate beneath a second oceanic plate.
Lithosphere
A strong rigid layer made up of the uppermost part of the mantle and the crust. has crack that meet at boundaries, known as plates.
Pumice
A type of igneous rock that contains air bubbles. A rock that floats because it is not dense. Holes in the rock make it flatter like styrofoam
Volcano
A vent which transfers molten rock known as magma from the subsurface to the earth's surface; a natural way the earth and other planets have of cooling off and releasing internal heat and pressure
Dike
A vertical slab of volcanic rock formed when magma forces itself across rock layers
scientific theory
A well-tested explanation for a wide range of observations or experimental results. Models of how a system operates and has been thoroughly tested. 1. It has to predict something 2. Should be a test that falsifies 3.Has to be overwhelmingly accepted by the science community
Intrusive Igneous Rocks
Also called plutonic rocks; form when magma crystallize at depth
Partial melting...
Always produces a higher silica magma than the original rock you were melting.
black hole
An object in space whose gravity is so strong not even light can escape.
Doppler effect
An observed change in the frequency of a wave when the source or observer is moving. Higher pitches = shorter wavelengths. Lower pitches = longer wave lengths
mid-ocean ridge
An underwater moutain chain where new ocean floor is formed
Crystalline
Attends have a regular geometric repeating pattern. External crystal form
What does this leftover magma do?
Becomes more silica rich becomes you melt the minerals with the the most silica forest
Which of the following are types of ferromagnesium silicates?
Biotite andmuscovite can be classified as mica minerals because the y will split into thin sheets. However, biotite can also be classified as a ferromagnesium m ineral- along with amphibole, pyro xene, and olivine -because it contains iron and magnesium in its chemical formula.
Partial melting + silica enrichment during the cooling process
Causes the magma to look differently before rushing to the surface as magma by selectively removing elements as different minerals crystallize. Enriching the silica in the process by drawing out more magnesium and iron and not as much silica.
Magma Differentiation
Change in composition of a magma to produce a wide variety of different igneous rocks; change in the composition of a magma body, which can occur by assimilation, magma mixing, fractional crystallization
Big grains/visible
Cooled slowly, underground
Tiny, microscopic grain
Cooled very rapidly
Big Bang Theory
Cosmological model that explains the sudden development of the universe through expansion from a hot, dense state.
Intrusive Igneous
Course grained
Phaneritic rocks
Course-grained rocks; form in the earths surface; crystallize/cool slower
Cinder cones
Paricutin; small, conical in shape, steeply sloping, composed of almost all pyroclastic material
Andacites
Extrusive volcanic rocks. A magma body is plutonic or intrusive
Composite Volcanoes
Felsic
Degasses Poorly
Felsic
Explosive Eruptions
Felsic
High Silica (65+%)
Felsic
High Viscosity
Felsic
High Water Content
Felsic
Light Color
Felsic
Low Density
Felsic
Low Melting Point
Felsic
Pyroclastic Material (ash, cinders, bombs)
Felsic
Thick Magma
Felsic
Aphanitic Rocks
Fine Grained rocks; form from lava on or near the surface; crystallize rapidly
Lava domes
Form from eruptions of felsic magma
Caldera volcanoes
Form from eruptions which partially empty the magma chamber
shield volcano
Form from low viscosity lava flows (mafic) and have gentle slopes
Extrusive Igneous Rocks
Form when magma solidifies at Earth's surface (lava)
If it cold underground it would make
Gabbro
Volcanic gas
Gases that escape out of a magma
Volcanic gas
Gases that escape out of a magma's chamber of a volcano
Micas
Grow in sheets and separate in sheets •biotite - dark •muscovite -light
Common Volatiles in Magma
H20 (Water vapor), CO2 (Carbon Dioxide), SO2 (Sulfur Dioxide)
Shield Volcanoes
Hawaii, Mauna Loa; large, gentle sloping, composed of almost basalt; 90% of the volcano is lava rather than pyroclastic material
sill
Horizontal sheet pluton intrusion
Peridotite
Igneous rock that contains mostly olivine and pyroxene; considered ultramafic
Extrusive rock
Igneous rocks which form by the crystallization of magma at the surface of the Earth.
Continental arc
Line of volcanoes on a continental plate; the volcanoes are on a continent above a subducting oceanic plate.
backarc basin
Little divergent plate boundaries being the arc of a continental arc
What evidence do we have that supports the Condensation theory?
Inner planets are small and made up of rocks and metals; have very few low temperature elements. Outer planets are the farthest away from the sun and are made up of low temperature elements (hydrogen and helium) Also the orbital pattern of the planets is consistent with the Nebular Theory.
Andesitic Composition (intermediate)
Intrusive: Diorite Extrusive: Andesite
Basaltic Composition (Mafic)
Intrusive: Gabbro Extrusive: Basalt
Granitic Composition (Felsic)
Intrusive: Granite Extrusive: Rhyolite
Ultramafic Composition
Intrusive: Peridotite Extrusive: Komatite
What's has silica enrichment done fire our planet?
It has built our continents
If the magma cools above ground
It will make basalt
Orthocase
K spar
Pahoehoe lava
Kind of Lava which flows slowly, like wax dripping from a candle, forming a glassy surface with rounded wrinkles
Plutons
Large intrusive bodies of igneous rocks
Peridotite (Igneous)
Large visible plutonic rocks that are ultramafic. Usually green
Volcanic Hazards
Lava flows, pyroclastic flows, ash falls (Pompeii), Lahars (mudflow made up of volcanic debris), Gases can be toxic (Co2, SO2, H2S)
In partial melting...
Lower temperature materials are melted first, but it solidifies last. Olivine crystallizes before pyroxene.
What does water do the the melting point of a rock?
Lowers it
Dark Color
Mafic
Degasses Easily
Mafic
High Density
Mafic
High Melting Point
Mafic
Lava Flows
Mafic
Low Silica (45-52%)
Mafic
Low Viscosity
Mafic
Low Water Content
Mafic
Quiet Eruptions
Mafic
Shield Volcanoes
Mafic
Thin Magma
Mafic
If a mafic magma cooled off to form an igneous rock, that rock would...
Mafic magmas cool off to form plutonic (intrusive) igneous rocks .Basalt is an extrusive (volcanic) igneous rock and forms from cooling lava flows. The correct answer to this question would have been gabbro.
Difference between magma and lava
Magma is melted/molten rock in the subsurface, lava is molten rock on the earth's surface
Assimilation
Magma passes through a cooler rock and may partially melt the surrounding rock and incorporate this melt into the magma; addition of this melt to magma will make it more siliceous ex: peridotite xenolith in basalt
Magma Mixing
Magmas with different compositions come in contact with each other and mix; the mixed magma will have a composition somewhere between that of the original two magma compositions
Why do we get magma at hotspots?
Mantle plumes. Also the pressure drops because you're melting peridotite again, which result in mafic magma forming.
The very top of the Earth's mantle is the..
Mohorovicic discontinuity. Although the asthenosphere is near the top of the mantle, it is not the very top of the mantle. The boundary between the crust and mantle (chemical subdivisions) is within the lithosphere (physical subdivision) at the Moho.
Origin of Magma
Most magma originates in earth's uppermost mantle usually by divergent plate boundaries (sea floor spreading) Magma can also be generated when crustal rocks are heated to melt or when the oceanic lithosphere descends into the mantle
composite volcanoes
Mount st. Helens, Mount Etna; also called stratovolcanoes; moderately to steeply sloping; half lava half pyroclastics; composed primarily of intermediate composition (andesite & Dacite)
Rock
Naturally formed, consolidated and composed of one or more minerals
Ferromagnesium silicate
Olivines, pyroxene, amphiboles
Why are the inner planets so small?
Once you take away the hydrogen and helium, we are left with the leftover materials that make up our planets, not saying we do not have any, but not nearly as much as the other planets.
Partial melting
Only melting part of the rock and not the whole thing
Vent
Opening through which lava erupts
Volcanic hotspot
Places within the mantle where rocks generate magma
Planetary Revolutions (Orbits)
Planets all orbit counterclockwise (as viewed from the Earth's north pole, exactly as expected if they originally formed in a rotating nebula.) *Venus and Uranus ROTATE clockwise.
Lava
Produced when magma reaches earth's surface
What would happen if you partially melted continental crust?
Quartz would melt first because it has the highest silica. High silica, low temperature minerals writing be melted first.
stock
Regular magma blob cooling off
What does melting pyroxene do?
Releases more silica and oxygen into forming magma than melting olivine.
Rock Cycle
Representation of how rocks are formed, broken down, and processed in response to changing conditions. Processes may involve interactions of the geosphere with hydrosphere, atmosphere and/or biosphere
Intrusive
Rocks formed from magma forced into older rocks at depths within the Earths crust
When rocks are subducted deep into the Earth and subjected to intense heat and pressure they ...
Rocks subducted into the mantle and subjected to intense heat and pressure (and affected by chemically active fluids) will be metam orphosed. Lithification is a process that turns sediment into sedimentary rock and occurs in the upper couple of kilometers of the surface. Rocks subducted into the Earth are heated up, but pressure increases so much that it actually be comes more difficult for the rocks to melt.
Feldspar
Silica rich rock
Ferromagnesium silicate mineral
Silicate minerals in which cations of iron and magnesium form essential chemical components. The term is used to cover such minerals as the olivines, pyroxenes, amphiboles, and the micas biotite and phlogopite.
Common elements in Igneous Rocks
Silicon, Oxygen, ions of Aluminum, Calcium, Sodium, Potassium, Magnesium, and Iron
Lower temperature feldspar
Sodium rich
Pyroclastics
Solid volcanic materials such as ash and rocks
Geothermal Gradient
Temperature increases with depth in the earth along a gradient; averages 25C per KM in the upper crust; under normal conditions the geothermal gradient is not high enough to melt rocks; most rocks melt between 800-1200C
Igneous Texture
Texture is the overall appearance of a rock based on size, shape, and arrangement of mineral grains
transform boundary
The boundary between tectonic plates that are sliding past each other horizontally
Pyroclastic Flow
The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption
How does temperature affect viscosity
The higher the temperature, the higher the viscosity
The largest eruptions of lava
The largest outpourings of lava in Earth history are associated with fissure eruptions
Rock Cycle and Plate tectonics
The lithosphere comes closer to the surface and melts. At the mid ocean ridge solid rocks in the crust and upper mantle start to melt and form a new oceanic crust
With enough silica enrichment...
The magma can become intermediate
The thicker the crust
The more time the magma's has to rise and become enriched in silica
Bowen's Reaction Series
The order in which minerals crystallize from a basaltic magma depends on temperature; Olivine and Ca-rich plagioclase crystallize first and the olivine reacts to produce pyroxene Shows how if the process of removing minerals continues an originally basaltic magma can change to andesitic and then rhyolitic with falling temperature
continental crust
The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick
Viscosity
The type of explosion depends on the viscosity of lava. Viscosity is a fluids resistance to flow. Viscosity is determined by temperature, composition, and dissolved gases. The more viscus the lava and the greater the volume of gas content the more violent the eruption
Felsic magma
Thick Lower temperature high silica magma
Caldera
Volcanic depression much larger than the original crater, has a diameter of atleast 1 km. Usually formed by the collapse of land following a volcanic eruption
Volcanic tsunami
Volcanic flank crashes into the sea. A tsunami forms and propagates to distant coastlines
Volcanic aerosols
Volcanic particles in the atmosphere preventing energy from getting to the Earth. 1. Block energy and bounces it back into space 2. Absorb the energy above our heads
Why do Volcanoes erupt?
Volcanoes erupt because of density and pressure; the lower density of the magma relative to the surrounding rocks causes it to rise, as it rises bubbles start to form from the gas dissolved in the magma which exerts tremendous pressure and brings magma to the surface and forces it into the air
transform boundaries
a boundary where two plates slide past one another without creating or destroying lithosphere. Most are located on Mid-Ocean ridge segments
When oceanic crust subducts beneath continental crust...
a continental arc might form on the overriding plate
Batholith
a huge series of overlapping magma's chambers at latest 40 sq miles.
A galaxy is...
a large accumulation of stars and nebulae
A geologist finds an igneous rock consisting of large mineral grains, visible without magnification. This rock...
a) would be plutonic b) would be intrusive
During the rock cycle a sedimentary rock...
a)might undergo melting to eventually become an igneous rock b)might be subjected to intense heat and pressure to become a metamorphic rock c)might undergo weathering and erosion to eventually form a new sedimentary rock
Nebular Condensation Theory
a)states that the sun and planets formed in a contracting and rotating nebula b)explains why most asteroids in the solar system are found between Mars and Jupiter c)explains why all the planets orbit the sun in the same direction
proto-planets
almost a planet, lumps of hydrogen/helium orbiting in the solar system. Occur when nuclear fission does not take place
Andesitic Composition
also called Intermediate composition; 25% dark silicate minerals mainly amphbinole, pyroxene, biotite mica; associated with volcanic activity on volcanic island arcs
extrusive igneous rocks
also called volcanic rocks; form when molten rock solidifies at the surface or when volcanic debris falls on the Earth's surface
Submarine Eruptions
always basaltic, mid ocean ridge eruptions, form underwater, pillow basalts
Volcanoes
an opening in the Earth's crust through which molten lava, ash, and gases are ejected.
The inner planets - those closest to the sun (Mercury, Venus, Earth and Mars)...
are much smaller than the planets farthest from the sun
Which of the following are physical subdivisions of the Earth?
asthenosphere
Which of the following are types of igneous rocks?
basalt granite
Atoms in a magma's body
bond together to make minerals
Moho
boundary between crust and mantle
If a low silica, high temperature lava flow cooled off to form an igneous rock, that rock would...
c) probably be basalt
Lahars
can form even when a volcano isnt erupting
Nebula
collapsing disk of hydrogen and helium; positive feedback loop
Basaltic Composition
contain a high percentage of ferromagnesian minerals; referred to as mafic; have a high iron content; make up the ocean floor as well as many volcanic islands in ocean basins; basalt forms extensive lava flow on continents
Chemical Layers of Earth
crust, mantle, core
Stock
deep, intermediate intrusive body formed of coarse grained igneous rock; commonly granitic in composition; smaller than a batholith larger than a laccolith
Batholiths
deep, large intrusive body formed of coarse grained igneous rock; commonly granitic in composition
laccolith
deep, small intrusive body formed of coarse grained igneous rock, commonly granitic in composition; injected between sedimentary strata causing the overlying strata to arch upward
Mafic
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color. Gabbro
Volcano size
determined by the total volume of lava that has erupted
Which of the following rocks might make up a sill?
diorite. Sills -along with dikes, stocks, and batholiths form from cooling magma. Thus, they are made up of plutonic igneous rocks. Both tuff and obsidian are volcanic igneous rocks.
Pyroclastic materials
ejected from the volcano as ash or solid fragments that often solidify as they leave the volcanic vent or fly through the air
Volcanic Domes
extremely high viscosity, degassed, felsic lavas (i.e. obsidian)
intermediate
fall in the category between felsic and mafic rocks
The most common mineral in the Earth's crust is...
feldspar
Extrusive
fine-grained igneous rock that forms when magma cools quickly at or near Earth's surface. Vitric. Can be a mixture of different flows
Composite Volcanoes (Stratovolcanoes)
formed from explosive eruptions of pyroclastic material, followed by quieter flows of lava; have broad bases and sides that get steeper toward the top
Sedimentary Rocks
formed from particles of sand, pebbles, shells, and other fragments of material (sediments). Gradually the sediment accumulates in layers and over a long period of time hardens into rock (sandstone, limestone, shale)
Igneous Rocks
formed when magma (molten rock in the earth's interior) cools and hardens (Granite)
pyroclastics (tephra)
fragments expelled explosively from a volcano, quite common with felsic magma (explosive eruptions)
Crater
funnel shaped over the vent at the summit of the volcano
ALL mass exorts...
gravitational pull. The larger the object, the larger the pull.
Continental continental convergence
happens where 2 continental plates collide and push up creating mountain ranges
oceanic-oceanic convergence
happens where 2 oceanic plates push against one another, causing the colder, denser, older plate to buckle up and sink into the mantle. Hot magma comes from where the plate sank, creating new crust.
Active Volcano
has had at least one eruption in the past 10,000 years
Inactive (extinct) volcano
has not had an eruption for at least 10,000 years
Granitic Composition
have dominant minerals of quartz and potassium feldspar (light colored silicates); referred to as being felsic; Granitic rocks are rich in silica (70%) and constitute a large part of the continental crust
If a felsic magma chamber exploded, erupting molten material into the air...
he airborne melt would cool to form pyroclastics. Both basalts and andesites form from cooling lava flows. Pyroclastic material (e.g. ash)deposited during volcanic eruptions form the igneous rock "tuff".
The Big Bang Theory
helps us understand cosmic background radiation
high silica
high viscosity
Shortly after the Big Bang, energy began to coalesce into matter. The first atoms to form were...
hydrogen atoms
subduction zone
in tectonic plates, the site at which an oceanic plate is sliding under a continental plate.
Plutonic
intrusive
The Red Shift ..
is the observation that light from distant stars is shifted toward the long wavelength end of the spectrum
In volcanically - active regions dominated by felsic magma...
lahars would be common
volcano shape
largely determined by the type of lava that has erupted and its viscosity
blue shift
light shifted towards the short end of a spectrum.
5 layers of earth
lithosphere, asthenosphere, mesosphere, outer core, inner core
low silica content
low viscosity
Mafic magma
low viscosity, high temperature. Basaltic
Which of the following minerals would likely grow first in a cooling magma chamber?
plagiocase
Bowen's Reaction Series
shows us where rocks were formed and the temperature and silica content of the magma's it formed in.
Metamorphic Rock
result of a transformation of a pre-existing rock (igneous/sedimentary). The original rock is subject to very high heat and pressure, which causes obvious physical and/or chemical changes
Tuffs
results of pyroclastic material coming or raging from the sky due to volcanic eruptions
Condensation Theory
rocks and metals condense, hydrogen compounds stay vaporized. Hydrogen compounds and metals condense. If you're an atom closer to the sun, you're warmer and have more energy, you do not chemically bond with other elements. Certain alloys and metals are more stable the closer they are to the Sun.
volcanic neck
shallow intrusion formed when magma solidifies in the through of a volcano
dike
shallow, tabular intrusive structure that cuts across any layering in host rock
sill
shallow, tabular intrusive structure that parallels layering in host rock
In volcanically-active regions dominated by mafic magma...
shield volcanoes would be common
Aa lava flow
surface rough; jagged blocks & spiny projections; lower temperature, less fluid
xenolith
suspended blocks of host rock found in plutons
The Big Bang theory predicts...
that rapid energy that got carried through space eventually evolved into cosmic background radiation
magma chamber
the body of molten rock that feeds a volcano
Moho
the boundary between the earth's mantle and crust
Geothermal gradient
the gradual increase in temperature with depth in the crust
Planetary Accretion
the idea that there are planetary losers and winners. Winners are considered planets that swept up other planets in their interaction.
Flood Basalts
very fluid basalts, extremely large in volume, creates extensive lava plateaus, some parts of the world are covered by thousands of square KM of thick basalt lava flows
Obsidian
volcanic glass
ductile
when solids have fluid like behaviors
continental collision
when two continental plates collide pushing the continental crust up to form mountains
Magmas with low viscosity...
would be very runny
Magma forms at
•continental rifts •divergent plate boundaries •hotspots