METAMORPHIC ROCKS Flashcards
Different temperature and pressure ranges create specific sets of metamorphic minerals that are called metamorphic facies. Using the graph, determine what facies a rock would be found in if it was buried 30 km deep and heated to a temperature of approximately 200 degrees
Blueschist
Shale, a sedimentary rock, can be subjected to high heat and pressure through
burial during continental collision.
What type of metamorphism would occur at a plate boundary where two continents are colliding?
Dynamothermal or regional metamorphism
Which type of foliation does gneiss have?
Compositional layering
During metamorphism, the process that changes the crystal structure of a mineral without changing its chemical composition is called
phase change.
Which agent of metamorphism involves hot water moving ions?
Interaction with hydrothermal fluids
Metamorphic grade is determined mainly by
temperature.
Identify the metamorphic process that is shown in the image.
Recrystallization
The temperature range for the formation of low-grade metamorphic rocks is __________ degrees C.
250 to 400
Which nonfoliated metamorphic rock forms from the metamorphism of limestone?
Marble
Which statement about the pathways of the rock cycle is TRUE?
Granite that is eroded, transported, deposited, and lithified will become a sedimentary rock.
Using the graph, determine what type of metamorphism (related to its geologic setting) a rock would likely be experiencing if it was at a depth of 20 km and heated to a temperature of 500 degrees C.
Mountain belt metamorphism
Metamorphism can occur in the surrounding rock as an igneous pluton forms. Which type of metamorphism is most likely to occur in the surrounding rock?
Thermal or contact metamorphism
A rock experienced melting then cooling, burial to deep depths during mountain building, and then uplift and weathering. Which pathway did this rock take through the rock cycle?
Igneous → metamorphic → sedimentary
When a rock is subjected to compressional pressure, the grains will
elongate perpendicular to the direction of stress.
In a rock undergoing metamorphosis, which type of stress occurs when one part of a rock moves sideways relative to the rest of the rock?
Shear stress
Which of the following describes an igneous to metamorphic to sedimentary path through the rock cycle?
A granite becomes buried and heated to form gneiss, and is then uplifted and eroded to make sand.
Which process brings metamorphic rocks to the surface over time?
Exhumation
The fine-grained foliated metamorphic rock formed from the metamorphism of shale or mudstone is called
slate.
Identify the metamorphic process that causes grains to warp and/or elongate but not melt or dissolve.
Plastic deformation
A nonfoliated metamorphic rock that is composed entirely of calcite is called
marble
Clay minerals within a buried body of slate are recrystallized at high temperatures and pressures to form mica, producing a rock called phyllite. This is an example of
metamorphism
Which of the following is a high-grade metamorphic rock?
gneiss
In the formation of gneiss (from a granite protolith), distinctive compositional bands form because of
crystals dissolving, with atoms and ions migrating and reorganizing as new crystals.
What was the direction of compression that formed the foliation in the image below?
in and out of the image, pulling outward
Thermal (contact) metamorphism occurs
in areas surrounding igneous intrusions.
Foliation may include the alignment of __________ in a metamorphic rock.
minerals
Which list properly orders these foliated metamorphic rocks from lowest grade to highest grade?
slate, phyllite, schist, and gneiss
Regional metamorphism
is another name for dynamothermal metamorphism.
Which of the following is a common foliated metamorphic rock?
gneiss
What is a primary difference between phyllite and schist?
Mica crystals within schist are larger than those within phyllite.
A buried body of shale is subjected to differential stress, causing clay minerals to realign and produce slate. This is an example of
metamorphism
Two common metamorphic rocks that typically lack foliation are __________ and __________.
quartzite; marble
What type of metamorphism affects the greatest volumes of rock and produces the greatest variety in metamorphic rock types?
dynamothermal
Rocks subjected to __________ feel a squeezing motion.
compression
Which of the following is a common protolith involved in the formation of slate?
shale
Consult the figure below. The region of thermally metamorphosed rock surrounding a cooled pluton is called a(n)
aureole
Foliated metamorphic rocks possess
mineral grains in preferred orientations or patterns of association such as banding.
Which of the following processes CANNOT occur in the formation of metamorphic rock?
complete melting of the rock, followed by solidification to form a new rock
Slaty cleavage, schistosity, and compositional banding are all examples of
foliation
