Chapter 7
Along which of the three lines shown in this diagram would you expect to find high-pressure, low-temperature metamorphic mineral assemblages?
A
Why do metamorphic rocks usually record the maximum pressure and temperature conditions of metamorphism?
Because fluids present during program metamorphism are often gone by the time pressure and temperature decrease
______ metamorphism occurs when high temperature is dominant factor, whereas pressure can be quite low.
Contact
Heat for metamorphic processes comes from which of the following sources?
Earth's interior Magma bodies
______ metamorphism occurs when hot fluids metamorphose a rock.
Hydrothermal
Which of these are types of metamorphism?
Hydrothermal metamorphism shock metamorphism regional metamorphism contant metamorphism
Match the nonaffiliated metamorphic rock with its parent rock.
Marble= limestone quartzite=sandstone hornfels=shale or basalt
Which type of rock is formed through transformations in solid state?
Metamorphic
______ refers to changes to rocks that take place in Earth's interior without melting.
Metamorphism
Foliation in metamorphic rocks formed within a subduction zone is formed by ______.
Shearing
Which of the following are examples of differential stress?
Shearing and compression
______ is a very fine-grained metamorphic rock that splits easily along flat parallel planes.
Slate
Match the foliated metamorphic rocks with their descriptions.
Slate= is very fine-grained and splits easily along flat parallel planes Phyllite=has newly formed micas that are larger than the platy minerals Schist= has minerals that are parallel and visible to the naked eye Gneiss= contains alternating bands of light-and-dare-colored minerals
Match the types of foliation with their correct descriptions.
Slaty cleavage= splits easily along flat and parallel planes schistose= coarse platy minerals grown parallel to a plane due to differential stress Gneissic= minerals separated into distinct alternating layers
A gneiss is a metamorphic rock with ______.
alternating bands of light- and dark-colored minerals
Metamorphic reactions are difficult to duplicate in a laboratory because they ______.
are extremely slow
The separation of light- and dark-colored minerals into bands indicates that gneiss forms ______.
at very high pressures and temperatures
The zone of contact metamorphism around an intrusion is called a(n) ______.
aureole
Water is the most important fluid involved in metamorphism; another important fluid is ______.
carbon dioxide gas
The stable cores of continents are known as ______.
cartons
During metamorphism, clay minerals recrystallize into mica because ______.
clay minerals are not stable under high pressures and temperatures
Nonfoliated metamorphic rocks are named based on their ______.
composition
which of the following are examples of differential stress?
compression shearing
Pressure applied equally on all surfaces of a substance as a result of burial or submergence is called ______ pressure.
confining
Metasomatism is often associated with ______ metamorphism because cooling magma is a good source for hydrothermal fluids and ions.
contact
______ metamorphism occurs adjacent to a body of magma that intrudes relatively cool country rock.
contact
______ metamorphism occurs when high temperature is the dominant factor, whereas pressure can be quite low.
contact
A stable mineral does not ______.
convert to another mineral react with another substance
Granitic plutons and metamorphic rocks make up ______.
cratons
Minerals crystallized under high pressure and more ______ because the pressure forces atoms closer together into a more closely packed crystal structure.
dense
An object is subjected to ______ stress when forces on it are stronger in one direction and weaker in another direction.
differential
Regional metamorphic rocks are almost always foliated, indicating ______ stress during recrystallization.
differential
______ ore deposits are those where the ore minerals are deposited as fine grains distributed throughout the rock, rather than concentrated in veins.
disseminated
A rock that is capable of being bent or molded under stress is called ______.
ductile
Rocks subjected to shearing will ______.
flatten and lengthen
If a metamorphic rock is ______, you need only to determine the type of texture and not the mineral content, to name the rock
foliated
If a metamorphic rock is ______, you need only to determine the type of texture and not the mineral content, to name the rock.
foliated
When considering the texture of a metamorphic rock, take into account whether is it ______ or non foliate..
foliated
Metamorphic rock textures include ______.
foliated and nonfoliated
When a metamorphic rock has a planar texture, with multiple parallel layers, it is said to be ______.
follated
Stress is measured as ______.
force per unit area
The increase in temperature with depth is called the ______ ______.
geothermal gradient
The banded metamorphic rock shown here is ______.
gneiss
The rocks found in cratons are largely ______.
granites metamorphics
The rocks found in creations are largely ______.
granites and metamorphics
Foliation in metamorphic rocks that form in the region marked by the red circle on this diagram will be approximately ______.
horizontal
As seen in this figure, ______ processes are important at mid-oceanic ridges where water descends through fractures in the oceanic crust.
hydrothermal
Mylonites are rocks composed of compacted pulverized rock. They are believed to form ______.
in fault zones
The chemical composition of a metamorphic rock ______.
is usually the same as that of the parent rock
A(n) ______ is a line connecting points of equal temperature, shown in this illustration as red dashed lines.
isotherm
The parent rock for marble is ______.
limestone
Isotherms are ______.
lines of equal temperature
The study of metamorphic rocks provides information about the conditions are processes within the ______, and has alded our understanding of plate tectonics.
lithosphere
A diver senses confining pressure proportional to the weight of overlying water. Likewise, an object buried deeply within the Earth's crust is compressed by strong confining pressure called ______ pressure.
lithostatic
The two most common nonfoliated metamorphic rocks are ______.
marble quartzite
Texture and mineralogical transformations that occur in the solid state create rock.
metamorphic
The degree of metamorphism, which is controlled by the pressure and temperature conditions under which it occurred, is referred to as ______.
metamorphic grade
Contact, regional, and hydrothermal are important types of ______.
metamorphism
______ is a mixed igneous and metamorphic rock.
migmatite
Schist is a metamorphic rock with ______.
minerals that are parallel and visible to the naked eye
Most metamorphism occurs at ______ in the Earth's crust.
moderate and great depths
Metamorphism refers to changes to rocks that take place in the Earth's interior. These changes can include ______.
new texture new mineral assemblages
Phyllite is a metamorphic rock with ______.
newly formed micas that are larger than the platy minerals
The texture of this metamorphic rock is ______.
nonfoliate
Because differential stress is not significant factor during contact metamorphism, contact metamorphic rocks are generally ______. For example, when magma intrudes shale, it is metamorphosed to ______.
nonfollated hornfels
The pressure gradient is approximately ______ for 3.3 kilometers of burial in the crust.
one kilobar
The pressure gradient is approximately ______ for 3.3 kilometers of burial un the crust.
one kilobar
A rock that is later changed into a metamorphic rock is called a(n) ______.
parent rock
Migmatite forms when ______.
part of a rock melts and crystallizes and igneous rock while the rest is metamorphosed
Shearing occurs when ______.
parts of a rock move or slide relative to one another in a plane
Slate is used for making which of the following?
pool tables chalkboards roof tiles
Most of the world's copper comes from disseminated deposits associated with an intrusion. These deposits are called ______.
porphyry copper deposits
The ______ ______ is the increase in lithostatic pressure with depth.
pressure gradient
Confining (or lithostatic) pressure is ______.
pressure that is applied equally on all surfaces of a rock as a result of burial or submergence
confining (or lithostatic) pressure is ______.
pressure that is applied equally on all surfaces of a rock as a result of burial or submergence
The ore minerals containing metals such as zinc, gold, and silver are usually found in ______.
quartz veins
The two most common nonaffiliated metamorphic rocks are ______.
quartzite marble
Most metamorphic rocks found on the Earth's surface formed through ______ metamorphism.
regional
Changes in the mineral assemblage of a metamorphic rock from high grade to lower grade are referred to as ______ metamorphism.
retrograde
The foliated metamorphic rock shown here is ______.
schist
The hydrothermal metamorphism of basalt and gabbros close to divergent boundaries is sometimes called ______.
seafloor
The parent rock of slate is usually ______.
shale
Phylite is a rock that is transitional between ______ and schist; as such, we expect it to form at a depth between where the other two have formed.
slate
The fine-grained, foliated metamorphic rock shown here is ______.
slate
______ develops under temperatures and pressures only slightly greater than this found in the sedimentary realm.
slate
Rank the progressive metamorphism from lowest grade (top) to highest (bottom) among these rocks.
slate phyllite schist gneiss migmatite
Rank the progressive metamorphism from lowest to grade (top) to highest (bottom) among these rocks.
slate phyllite schist gneiss migmatite
Rank the three very different textures from lowest to highest degree of metamorphism.
slaty schistose gneissic
A mineral is said to be ______ if, given enough time, it does not react with another substance or convert to a new mineral or substance.
stabel
A mineral is said to be ______ if, give enough time, it does not react with another substance or convert to a new mineral or substance.
stable
When forces are applied to an object, the object is under ______.
stress
The presence of high-pressure, low-temperature minerals such as glaucophane, in a metamorphic rock indicates that it formed in a(n) ______ zone.
subduction
Regional metamorphic rocks are typically foliated because they form under differential stress. The differential stress is due to ______.
tectonism and mountain building
The differential stress associated with regional metamorphism is the result of ______.
tectonism in the region
Minerals are stable within a given ______ and ______ range.
temperature pressure
The minerals that are found in a schist depend upon ______.
temperature pressure partent rock
High-grade metamorphic rocks form at high ______.
temperatures
The temperature range over which a mineral is stable depends upon ______.
the pressure conditions the presence of water
One bar of pressure is equivalent to ______.
the pressure of the atmosphere at sea level
Geologists use the presence of one or more minerals in a metamorphic rock to infer ______.
the temperature and pressure during metamorphism
Regional metamorphic rocks are almost always foliated because ______.
they have experienced differential stress during recrystallization of the minerals
Water is important during hydrothermal metamorphism because it ______.
transports ions increases the rate of metamorphism
Names of foliate metamorphic rocks are based primarily upon their ______.
type of foliation
When a hydrothermal rock crystallizes within a preexisting fracture in a rock, it forms a hydrothermal ______.
vein
Retrograde metamorphism will only occur if additional ______ is/are added to the rock after peak metamorphism.
water
The most important fluid involved in metamorphic processes is ______.
water
The new ions introduced during metasomatism are carried by ______.
water