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65 terms

Geology Ch 7

STUDY
PLAY
A body of gneiss is subjected to heat and forms a melt. Later the melt cools and crystallizes to form a(n) : . a., metamorphic rock b., igneous rock c., sedimentary
b. igneous rock
Metamorphism brings changes in mineral arrangement and the texture of rocks, but it never leads to new mineral assemblages. a., true b., false
b. false
A buried body of aragonitic limestone is recrystallized at low temperatures and pressures, producing calcite; this is an example of : . a..diagenesis b..erosion c..metamorphism d..weathering
a. diagenesis
A buried body of shale is subjected to differential stress at temperatures greater than 200C, causing clay minerals to grow in preferred orientation and producing slate. This is an example of : . a..diagenesis b..erosion c..metamorphism d..weathering
c. metamorphism
At the surface, potassium feldspar reacts with water to form clay; this is an example of : . a..diagenesis b..erosion c..metamorphism d..weathering
d. weathering
Clay minerals within a buried body of shale are recrystallized at 400C and high pressure to form mica, producing a rock called phyllite; this is an example of : . a..diagenesis b..erosion c..metamorphism d..weathering
c. metamorphism
Metamorphism may be induced by : . a..contact with a hot pluton b..contact with hot groundwater c..heat and pressure associated with deep burial d..all of the above
d. all of the above
Differential stress will cause crystals to align in a preferred orientation unless the crystals are : . a..primarily mica b..platy c..equant d..elongate
c. equant
Squashing a fly with a flyswatter is an example of : . a..compression b..shear
a. compression
Spreading peanut butter on bread is an application of : . a..compression b..shear stress
b. shear stress
All metamorphic rocks are formed within a fairly narrow range of temperatures, approximately 400 to 600C. a..true b..false
b. false
A primary difference between phyllite and schist is : . a..schist contains mica, but phyllite contains only clay b..phyllite contains mica, but schist contains only clay c..mica crystals within schist are larger than those within phyllite d..mica crystals within phyllite are larger than those within schist
c. mica crystals within schist are larger than those within phyllite
The development of a preferred orientation of large, flaky mica crystals within metamorphic rock is termed : . a..slaty cleavage b..phyllitic luster c..schistosity d..compositional banding
c. compositional banding
Slaty cleavage, schistosity, and compositional banding are all examples of : . a..mineral cleavage b..foliation c..recrystallization d..sedimentary structures
b. foliation
Marble and quartzite are nonfoliated rocks because : . a..they are never found beneath fault zones or collisional mountain ranges b..both are dominated by minerals that produce equant grains c..both are dominated by minerals with crystalline structures that cannot be dissolved d..dynamothermal metamorphism can break down the structures of their constituent minerals, but neither of these minerals is stable in that metamorphic environment
b. both are dominated by minerals that produce equant grains
Two common metamorphic rocks that typically lack foliation are : . a..slate and phyllite b..gneiss and migmatite c..quartzite and marble d..schist and metaconglomerate
c. quartzite and marble
Compared to low-grade metamorphic rocks, high-grade rocks : . a..always contain more quartz and feldspar b..are produced closer to the surface, high in the stratigraphic column c..are produced at greater temperatures and pressures d..are produced at cooler temperatures, but greater pressures
c. are produced at greater temperatures and pressures
A mineral within a metamorphic rock that can be used to provide a narrow constraint on the temperature and pressure of formation of the rock is termed a(n) : . a..thermineral b..index mineral c..mafic mineral d..halide mineral
b. index mineral
The process of low-grade metamorphic rocks being altered to form high-grade metamorphic rocks is termed : metamorphism. a..foliated b..prograde c..retrograde d..dynamic
b. prograde
The process of high-grade metamorphic rocks being altered to form low-grade metamorphic rocks is termed : metamorphism. a..foliated b..prograde c..retrograde d..dynamic
c. retrograde
Phyllite would most likely be found : . a..in an aureole around a cooled igneous intrusion b..at the eroding base of an ancient collisional mountain range c..at depth within the mid-ocean ridge system d..within a meteorite impact crater
b. at the eroding base of an ancient collisional mountain range
The region of thermally metamorphosed rock surrounding a cooled pluton is called a(n) : . a..shear zone b..aureole c..oriole d..oleo
b. aureole
Rocks resulting from thermal (contact) metamorphism will not possess : . a..a new mineral assemblage distinct from that found prior to intrusion b..larger crystals than those characterizing the country rock prior to intrusion c..foliation d..silicate minerals
c. foliation
Regional metamorphism : . a..takes place at cool temperatures and low pressure b..takes place at cool temperatures but high pressure c..is another name for thermal metamorphism d..is another name for dynamothermal metamorphism
d. is another name for dynamothermal metamorphism
Which type of metamorphism affects the greatest volumes of rock? a..thermal metamorphism b..dynamothermal metamorphism c..dynamic metamorphism
b. dynamothermal metamorphism
The protolith subjected to metamorphism : . a..is always metamorphic rock to begin with b..is always igneous rock c..is always sedimentary rock d..may belong to any of the three primary rock types
d. may belong to any of the three primary rock types
The blueschist facies is a metamorphic realm of : . a..high temperature and pressure b..low temperature and pressure c..high temperature but relatively low pressure d..high pressure but relatively low temperature
d. high pressure but relatively low temperature
Within a single mountain range, : . a..only low-grade metamorphic rocks are likely to be found b..only high-grade metamorphic rocks are likely to be found c..it is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, low-, and intermediate-grade rocks
c. it is possible to find a variety of metamorphic rocks produced in distinct facies, including high, low, and intermediate grade rocks
Precambrian metamorphic rocks are exposed at the surface : . a..on Mars and Venus, but nowhere on Earth b..at places in continental interiors termed platforms c..at places in continental interiors termed shields d..at the bottom of the deep sea
c. at places in continental interiors termed shields
Net chemical change in metamorphic rock induced by reaction with hot groundwater is termed : . a..foliation b..metasomatism c..anachronism
b. metasomatism
The mineral assemblage within metamorphic rock is : . a..always identical to that found within the protolith b..dependent only on the mineral assemblage of the protolith c..dependent only on the temperature and pressure of formation d..dependent on both the mineral content of the protolith and the temperature and pressure of formation
d. dependent on both the mineral content of the protolith and the temperature and pressure of formation
In the formation of gneiss from granite, the distinctive compositional bands form due to : . a..crystals migrating within the rock b..crystals dissolving, and atoms and ions migrating and reorganizing as new crystals c..crystals melting, with new crystals solidifying in color bands d..the bizarre and seemingly unknowable nature of the blueschist metamorphic facies
b. crystals dissolving, and atoms and ions migrating and reorganizing as new crystals
As compared to the amphibolite metamorphic facies, the greenschist facies : . a..consists of lower-grade rocks b..consists of higher-grade rocks c..is an identical temperature and pressure regime; greenschists and amphibolites bear different mineral assemblages only because of differences in protolith chemistry
a. consists of lower grade rocks
. Thermal (contact) metamorphism occurs : . a..in areas surrounding igneous intrusions b..only where gneiss is in contact with schist c..as consequence of the sinking of a broad region to great depth d..only at the surface, where rock is in contact with the atmosphere
a. only where gneiss is in contact with schist
Dynamothermal metamorphism occurs when : . a..rock becomes buried deeply during continental collision and mountain building b..regression of the sea leads to erosion of sedimentary cover atop a body of rock c..the upper surface of a body of rock develops a thick soil profile d..a pluton causes metamorphism in a small surrounding region
a. rock becomes buried deeply during continental collision and mountain building
Which of the following processes cannot occur in the formation of metamorphic rock? a..realignment of minerals so that they develop a preferred orientation b..segregation of minerals into layers of different compositions c..solid-state rearrangement of atoms or ions to create a new assemblage of minerals d..complete remelting of the rock, followed by solidification to form a new rock
d. complete remelting of the rock, followed by solidification to form a new rock
Metamorphism, in broadest terms, involves : . a..the settling of crystals within a melt as it cools b..the sorting of grains by size, as is accomplished by rivers and beach waves c..cementation of loose grains and precipitation of new minerals into pore spaces d..changes in mineralogy and texture in response to heat and stress
d. changes in mineralogy and texture in response to heat and stress
. Gneiss typically forms under higher pressures than hornfels. a..true b..false
a. true
Which list properly orders metamorphic rocks from lowest to highest grade? a..conglomerate, sandstone, siltstone, shale b..shale, slate, phyllite, quartzite c..slate, phyllite, schist, gneiss d..gneiss, phyllite, schist, slate
c. slate, phyllite, schist, gneiss
Foliated metamorphic rocks possess : . a..leafy plant fossils (ancient foliage) b..a homogeneous texture resulting from randomly oriented grains c..a planar fabric consisting of mineral grains in preferred orientations or preferred patterns of association (banding) d..minerals precipitated directly from sea water
c. a planar fabric consisting of mineral grains in preferred orientations or preferred patterns of association
The preexisting rock which is subsequently altered to form a metamorphic rock is termed a : . a..parent rock b..source rock c..protolith d..premetarock
c. protolith
commonly serves as a protolith in the formation of marble. a..Limestone b..Sandstone c..Shale d..Slate
a. limestone
commonly serves as a protolith in the formation of phyllite. a..Limestone b..Sandstone c..Shale d..Slate
d. slate
commonly serves as a protolith in the formation of quartzite. a..Limestone b..Sandstone c..Shale d..Slate
b. sandstone
: commonly serves as a protolith in the formation of slate. a..Limestone b..Sandstone c..Shale d..Gneiss
c. shale
Rapid, deep burial of sediments in an accretionary prism leads to the formation of a metamorphic rock termed : . a..blueschist b..greenschist c..migmatite d..gneiss
a. blueschist
Meteorite impacts have been known to induce metamorphism of sediments and rocks. a..true b..false
a. true
Dynamothermal metamorphism produces : . a..foliated rocks only b..nonfoliated rocks only c..both foliated and nonfoliated rocks
c. both foliated and nonfoliated rocks
Thermal (contact) metamorphism produces : . a..foliated rocks only b..nonfoliated rocks only c..both foliated and nonfoliated rocks
b. nonfoliated rocks only
Burial metamorphism produces : . a..foliated rocks only b..nonfoliated rocks only c..both foliated and nonfoliated rocks
b. nonfoliated rocks only
The mineral glaucophane is associated with (a) high temperature and low pressure (b) high temperature and pressure (c) low temperature and pressure (d) high pressure and low temperature
d. high pressure and low temperature
A high grade metamorphic rock that can be formed from intense shearing is (a) phyllite (b) schist (c) slate (d) migmatite (e) gneiss
e. gneiss
Argillite is a low grade rock from (a) contact metamorphism (b) regional metamorphism (c) hydrothermal metasomatism
a.contact metamorphism
A metamorphic mineral change on a map is represented by (a) an isograd (b) the geotherm (c) a porphyroblast
a. an isograd
What has the best cleavage (a) slate (b) phyllite (c) schist (d) gneiss (e) migmatite
a. slate
What has the best cleavage (a) slate (b) phyllite (c) schist (d) gneiss (e) migmatite
c. schist
A equant material subjected to confining pressure from burial is (a) flattened to a disk (b) elongated like French bread (c) remains equant
c. remains equant
Mylonite will be found (a) in contact with plutons (b) in hydrothermal deposits (c) between schist and phyllite (d) on fault zones (e) in bolide impact craters
d. on fault zones
Marble forms from a limestone protolith in BOTH contact and regional metamorphism (a) T (b) F
a. T
Metamorphism at ocean ridges is mainly (a) contact (b) dynamic (c) hydrothermal (d) regional
c. hydrothermal
The father of the rock cycle was (a) Darwin (b) Hutton (c) Suess
b. Hutton
For rocks at the surface, the true starting point for the rock cycle would be (a) igneous (b) sedimentary (c) metamorphic
a. igneous
During the exhumation phase of mountain development, the next stop on the cycle would be (a) igneous (b) sedimentary (c) metamorphic
b. sedimentary
Is it true that one can go straight from Sedimentary to Igneous on the rock cycle? (a) Y (b) N
b. N
The plate boundary that accumulates the most change from sedimentary to metamorphic is (a) divergent (b) convergent (c) transform
b. convergent