Geology Chapter 4,5, and 7
The ________ ocean basin is rimmed by the most subduction zones. Atlantic Indian Pacific Arctic
Pacific
________ is characterized by very coarse mineral grains? Granite Obsidian Pegmatite Pumice
Pegmatite
________ is composed mainly of ferromagnesian minerals. Rhyolite Peridotite Granite Andesite
Peridotite
________ is thought to be common in the Earth's mantle but rare in the crust. Granite Pegmatite Pumice Peridotite
Peridotite
________ is the dominant feldspar in basalt. Plagioclase Microcline Orthoclase Pyroxene
Plagioclase
A (an) ________ texture represents a single, long period of cooling and crystallization. phaneritic pyroclastic aphanitic glassy
phaneritic
A ________ texture would be most unlikely to occur in an extrusive igneous rock. phaneritic pyroclastic aphanitic glassy
phaneritic
At low pressures and in the absence of water, rhyolites and granites begin to melt at about ________. 800°C 300°C 6000°F 500°F
800
________ is named for a prominent, volcanic mountain range in western South America. Basalt Andesite Peridotite Pegmatite
Andesite
________ magma is the most abundant type of magma erupted at oceanic spreading centers. Basaltic Andesitic Granitic Pegmatitic
Basaltic
________ magma is the most abundant type of magma erupted at oceanic spreading centers. Basaltic Andesitic Granitic Pegmatitic
Basaltic
What volcanic events formed Crater Lake, OR? When did they take place? Landslides and volcanic mudflows dammed the Mazama River; 500 years ago. The crater of a large, extinct cinder cone filled with water; 5 million years ago. A powerful explosion blew away the top of a stratovolcano; 10 million years ago. Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.
Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.
What volcanic events formed Crater Lake, OR? When did they take place? Landslides and volcanic mudflows dammed the Mazama River; 500 years ago. The crater of a large, extinct cinder cone filled with water; 5 million years ago. A powerful explosion blew away the top of a stratovolcano; 10 million years ago. Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.
Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.
Which kind of eruptive activity is most likely to be highly explosive? Fissure eruptions feeding lava to flood basalt accumulations. Lava flows from a large shield volcano on an oceanic island. Eruptions of big, continental margin, composite cones or stratovolcanoes. Lava flows from a large cinder cone complex.
Eruptions of big, continental margin, composite cones or stratovolcanoes.
Which kind of eruptive activity is most likely to be highly explosive? Fissure eruptions feeding lava to flood basalt accumulations. Lava flows from a large shield volcano on an oceanic island. Eruptions of big, continental margin, composite cones or stratovolcanoes. Lava flows from a large cinder cone complex.
Eruptions of big, continental margin, composite cones or stratovolcanoes.
________ often contain gem-quality crystals of minerals such as beryl and tourmaline and high concentrations of relatively rare elements such as lithium, boron, and beryllium. Basaltic lavas Diorite plutons Welded tuff sheets Granitic pegmatites
Granitic pegmatites
________ tend to increase the explosive potential of a magma body beneath a volcano. Low viscosity; low dissolved gas content High viscosity; low dissolved gas content Low silica content, low viscosity High viscosity and dissolved gas
High viscosity and dissolved gas
What is the largest, known volcano in the Solar System? Mount Olympus, Greece, Earth Olympus Mons, Mars Mauna Kea, southern hemisphere, Mars Mauna Loa, Hawaii, Earth
Olympus Mons, Mars
What is the largest, known volcano in the Solar System? Mount Olympus, Greece, Earth Olympus Mons, Mars Mauna Kea, southern hemisphere, Mars Mauna Loa, Hawaii, Earth
Olympus Mons, Mars
What does it mean to have an andesitic composition? Rocks contain mostly olivine and pyroxene. Rocks have the same composition as basalt. Rocks have a composition between that of granite and basalt. Rocks contain mostly quartz.
Rocks have a composition between that of granite and basalt.
The 1991 Pinatubo eruption in the Philippines caused brilliantly colored sunrises and sunsets to be seen for the next few years. What caused this phenomenon? Sulfur dioxide and other erupted gases formed aerosols in the stratosphere. The eruption added large amounts of carbon dioxide to the atmosphere. The eruptive cloud destroyed parts of the Earth's protective ozone layer. Radioactive atoms blown into the atmosphere glowed red as they decayed.
Sulfur dioxide and other erupted gases formed aerosols in the stratosphere.
The 1991 Pinatubo eruption in the Philippines caused brilliantly colored sunrises and sunsets to be seen for the next few years. What caused this phenomenon? Sulfur dioxide and other erupted gases formed aerosols in the stratosphere. The eruption added large amounts of carbon dioxide to the atmosphere. The eruptive cloud destroyed parts of the Earth's protective ozone layer. Radioactive atoms blown into the atmosphere glowed red as they decayed.
Sulfur dioxide and other erupted gases formed aerosols in the stratosphere.
Lava flows are typically finer grained than intrusive igneous rocks. Why? Intrusive magma flows onto the Earth's surface and cools very slowly, allowing many small mineral grains to grow. The extrusive magma cools quickly so the mineral grains do not have time to grow. The extrusive magma, because it is deep below the surface, cools very slowly producing very small mineral grains. Intrusive magma is cooler because it is well insulated by the surrounding rock.
The extrusive magma cools quickly so the mineral grains do not have time to grow.
Which of the following best describes an aphanitic texture? The rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope. The mineral grains have glassy textures. The rock consists of broken, volcanic-rock and mineral fragments. The rock is crystalline; mineral grains are of distinctly different sizes.
The rock is crystalline; mineral grains are too small to be visible without a magnifying lens or microscope.
________ are usually the most abundant gases emitted during basaltic volcanism. Water and carbon dioxide Neon and ammonia Chlorine and sodium Oxygen and nitrogen
Water and carbon dioxide
________ are usually the most abundant gases emitted during basaltic volcanism. Water and carbon dioxide Neon and ammonia Chlorine and sodium Oxygen and nitrogen
Water and carbon dioxide
What do pumice and obsidian have in common? basaltic composition phaneritic texture glassy texture ultramafic composition
glassy texture
The Columbia Plateau in Washington and Oregon is ________. a field of large stratovolcanoes a thick stack of welded-tuff layers a flood basalt plateau a caldera filled with rhyolite lava flow.
a flood basalt plateau
Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble? pahoehoe scoria pillow lava aa
aa
Which of the following igneous rocks exhibit aphanitic texture? andesite; rhyolite granite; gabbro andesite; diorite rhyolite; gabbro
andesite; rhyolite
The average composition of rocks comprising a large composite cone or stratovolcano is similar to a (an) ________ magma. basaltic rhyolitic andesitic ultramafic
andesitic
The average composition of rocks comprising a large composite cone or stratovolcano is similar to a (an) ________ magma. basaltic rhyolitic andesitic ultramafic
andesitic
Volcanic bombs originate ________. as ash particles that join together in the eruptive plume and fall as cobble-sized objects as blocks of volcanic rock ejected from an erupting volcanic crater as erupted magma blobs that partly congeal before falling to the ground as laser-guided, granite blocks launched from a supersonic jet
as erupted magma blobs that partly congeal before falling to the ground
Change in a magma's composition due to melting of surrounding country rock is called _______. magma mixing crystal settling Bowen's reaction series assimilation
assimilation
Changing the composition of magma by incorporating surrounding host rock is known as ________. partial melting assimilation magma mixing differentiation
assimilation
Which igneous rock or magma has the lowest silica (SiO2) content? granite andesite basalt peridotite
basalt
________ is the dominant lava erupted from volcanoes on Hawaii and Iceland. Andesite Rhyolite Peridotite Basalt
basalt
Kilauea and Mauna Loa are ________. explosive, rhyolitic volcanoes small, basaltic cinder cones andesitic stratovolcanoes basaltic shield volcanoes
basaltic shield volcanoes
Which natural phenomenon occurs for many years after major explosive volcanic eruptions such as Tambora and Pinatubo? a worldwide rise in sea level of one to three centimeters heavy falls of volcanic ash within 100 km of the volcano unusually warm weather in the tropics and subtropics brilliantly colored sunrises and sunsets
brilliantly colored sunrises and sunsets
Which natural phenomenon occurs for many years after major explosive volcanic eruptions such as Tambora and Pinatubo? a worldwide rise in sea level of one to three centimeters heavy falls of volcanic ash within 100 km of the volcano unusually warm weather in the tropics and subtropics brilliantly colored sunrises and sunsets
brilliantly colored sunrises and sunsets`
Intrusive igneous rocks are _____ and _____. fine-grained; formed at the surface fine-grained; formed at depth coarse-grained; formed at depth coarse-grained; formed at the surface
coarse-grained; formed at depth
All of the following are factors that affect the generation of magma except for ________. volatiles heat pressure crystal size
crystal size
________ has the same mineral composition as andesite. Gabbro Granite Diorite Basalt
diorite
Visible quartz and potassium feldspar grains are the main constituents in a ________. rhyolite basalt granite gabbro
granite
Relative to water, syrup has a _____ resistance to flow and therefore a _____ viscosity. higher; lower higher; higher lower; lower lower; higher
higher; higher
Bowen's reaction series predicts the sizes of the different mineral grains that grow from crystallizing magmas.
false
In general, cinder cones are much larger than shield volcanoes.
false
Most lava crystallizes to form igneous rocks with phaneritic textures.
false
Olivine and quartz commonly crystallize together from mafic or basaltic magmas.
false
Pegmatites are smaller volume, intrusive bodies with glassy textures.
false
The last minerals to crystallize on Bowen's Reaction Series result in igneous rocks with a ________ composition. intermediate ultramafic mafic felsic
felsic
Xenoliths are associated most closely with which magmatic process and igneous rock body? vesiculation; pumice lump intrusion; granitic batholith columnar jointing; lava flow magmatic differentiation; gabbro sill
intrusion; granitic batholith
A ________ is a near surface, intrusive, igneous rock body that results from local inflation of a horizontal sill. batholith dike laccolith volcanic neck
laccolith
A ________ is a near surface, intrusive, igneous rock body that results from local inflation of a horizontal sill. th dike laccolith volcanic neck
laccolith
In a porphyritic volcanic rock, which mineral grains are the last to crystallize? pegmatites vesicles phenocrysts matrix or groundmass
matrix or groundmass
Consider the Bowen's reaction series. Which mineral would you expect to see as a phenocryst in a porphyritic basalt? quartz sodium-rich plagioclase orthoclase olivine
olivine
Which of the following minerals crystallize early in Bowen's reaction series? muscovite olivine quartz biotite
olivine
The ________ ocean basin is rimmed by the most subduction zones. Atlantic Indian Pacific Arctic
pacific
Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface? aa scoria pegmatitic pahoehoe
pahoehoe
Which of the following best describes seamounts and islands of the deep ocean basins? huge granite batholiths intruded beneath the ocean floor domed gabbro intrusions and massive, submarine, rhyolitic, pyroclastic cones andesitic pyroclastic rocks submerged when the mountains sank below sea level piles of basaltic lava flows built up from the ocean floor by multiple, summit and flank eruptions
piles of basaltic lava flows built up from the ocean floor by multiple, summit and flank eruptions
Which of the following best describes seamounts and islands of the deep ocean basins? huge granite batholiths intruded beneath the ocean floor domed gabbro intrusions and massive, submarine, rhyolitic, pyroclastic cones andesitic pyroclastic rocks submerged when the mountains sank below sea level piles of basaltic lava flows built up from the ocean floor by multiple, summit and flank eruptions
piles of basaltic lava flows built up from the ocean floor by multiple, summit and flank eruptions
The recent (geologically) volcanic activity in Yellowstone National Park is ________. related to a divergent plate boundary related to a transform plate boundary related to plate subduction related to intraplate, hot spot volcanism
related to intraplate, hot spot volcanism
Which one of the following shows the correct order (left to right) of decreasing magma viscosity? basalt, rhyolite, andesite rhyolite, andesite, basalt basalt, andesite, rhyolite andesite, rhyolite, basalt
rhyolite, andesite, basalt
A ________ volcano is a very large, gently sloping mound composed mainly of basaltic lava flows. stratospheric shield composite cinder cone
shield
A ________ volcano is a very large, gently sloping mound composed mainly of basaltic lava flows. stratospheric shield composite cinder cone
shield
A ________ is an intrusive, igneous rock body that is tabular and concordant. pluton laccolith dike sill
sill
Stocks differ from batholiths because of their ______. shape size position in the crust composition
size
Which kind of volcanism is typical of mid-oceanic ridge systems? explosive; rhyolitic, pyroclastic flows explosive; composite cones submarine; basaltic lava flows fissure eruptions; flood basalts fields
submarine; basaltic lava flows
Which kind of volcanism is typical of mid-oceanic ridge systems? explosive; rhyolitic, pyroclastic flows explosive; composite cones submarine; basaltic lava flows fissure eruptions; flood basalts fields
submarine; basaltic lava flows
The sizes, shapes, and arrangements of mineral grains in an igneous rock is known as ________. mineral content silica content Bowen's reaction series texture
texture
The two most important criteria used for classifying igneous rocks are _____. texture and temperature mineral composition and temperature texture and mineral composition texture and viscosity
texture and mineral composition
Which region has the greatest concentration of currently active volcanoes? the circum-Pacific area the area surrounding the Red Sea European Russia and Siberia the coastal plain of western Africa
the circum-Pacific area
Which region has the greatest concentration of currently active volcanoes? the circum-Pacific area the area surrounding the Red Sea European Russia and Siberia the coastal plain of western Africa
the circum-Pacific area
The major difference between phaneritic and aphanitic texture is _____. the size of the crystals the chemical composition the type of minerals the rocks contain how much silica is present
the size of the crystals the chemical composition the type of minerals the rocks
Which of the following is associated with deep mantle hot spots? the volcanoes of Hawaii and the recent activity in Yellowstone National Park the very young cinder cones scattered across the southwestern United States Vesuvius and the other volcanoes of Italy Mt. St. Helens and other volcanoes of the Cascade Mountains
the volcanoes of Hawaii and the recent activity in Yellowstone National Park
The Icelandic volcanoes are related to plate tectonics because ________. they lie on a spreading center where two plates are converging they lie along a subduction zone where two plates are diverging they lie on a spreading center where two plates are moving apart they lie on a subduction zone where two plates are converging
they lie on a spreading center where two plates are moving apart
Ash and lapilli are different sized pyroclastic particles.
true
Basalt is the aphanitic or fine-grained equivalent of gabbro.
true
Basalt is the most common magma erupted along oceanic rift systems.
true
Dissolved gases may comprise up to a few percent by weight of a magma.
true
Glassy igneous rocks form when magma cools too fast for mineral grains to grow.
true
Magma generation at depth almost always involves partial melting, not complete melting of the source rock.
true
Olivine is an important mineral in peridotites and other ultramafic rocks.
true
Small amounts of water can lower partial melting temperatures in silicate rocks.
true
The process of magmatic differentiation can generate residual, more felsic magmas from mafic magmas such as basalt.
true
The viscosities of magmas increase with increasing percentages of silica.
true
A ________ is an open cavity in a volcanic rock that was filled by a gas bubble when the lava was still mainly liquid. phenocryst porphyrocryst xenocryst vesicle
vesicle
The most abundant gas found in magma is ______. nitrogen carbon dioxide chlorine water vapor
water vapor
