Metamorphic rocks form from taking a pre-existing rock and increasing the pressure and temperature of the rock changing the rock
In metamorphic high temperature and pressure cause both _______ and _________ changes.
Physical; chemical
Typically with metamorphic rocks occurs ______ km below the surface at temperatures around ________.
A) 10-30 km; 200-600°C
What are the factors that influence metamorphic changes?
Temperature
Pressure; both lithostatic and differential pressure
Fluid activity
How does temperature influence metamorphic changes?
Temperatures causes recrystallization and speeds up reactions meaning the bonds rapidly break and reform causing a bigger rock sometimes
How does pressure influence metamorphic changes?
There are 2 types of pressures that influence metamorphic changes lithostatic pressure and differential pressure.
Differential pressure results in the development of foliation
How does Fluid activity influence metamorphic changes?
Fluid activity may introduce new chemicals and change the rocks bulk composition; speeding up reactions
Under dry conditions, most minerals react very _____, but when even small amounts of fluid are introduced, reaction rates ____ with metamorphic rocks.
D) slowly; increase
Define recrystalization
Recrystalization is the metamorphic process that occurs under situations of intense temperature & pressure where grains molecules or atoms of a rock or mineral are packed closer together creating a new crystal structure.
Define lithostaic pressure
Lithostatic pressure is the pressure exerted on rocks by the weight of overylying rocks
Define differential pressure
Differential pressure is the pressure that is not applied equally to all sides of a rock body
Define foliation
Foliation is the processes of being split into thin sheets is the result of differential pressure
Name the types of metamorphism
Regional metamorphism
contact metamorphism
burial metamorphism
hydro-thermal metamorphism
cataclysmic metamorphism
What is regional metamorphism?
Regional metamorphism affects the rocks in a large region of the crust, e.g. areas undergoing mountain building (most commonly at convergent boundaries)
tends to produce foliated rocks
metamorphic grade varies depending on P,T
What is contact metamorphism?
Contact metamorphism is the heating of rocks adjacent to igneous intrusions due to heat from magma (not a place to find foliation)
What is burial metamorphism?
Burial metamorphism affects rocks deep in sedimentary basins and is low grade metamorphism due to the deep burial of sediments
results from high lithostatic pressure
Shallow marine setting after millions of years--Fossils can get preserved
What is hydro-thermal metamorphism?
Hydro-thermal metamorphism resluts from hot, watery fluids altering rock; important at mid-ocean ridges
What is cataclysmic metamorphism (dynamic)?
Cataclysmic metamorphism (dynamic) results from high pressure alterations along faults producing mylonites
*suffered intense pressures
Name the foliated metamorphic rocks
slate
phylite
schist
gneiss
ampibolite
migmatite
Name the nonfoliated metamorphic rocks
marble
quatzite
greenstone
hornfels
anthracite
Metamorphic rocks are formed at/in the ______.
D) crust
True or False; If false restate to be true
Depending on the setting of the metamorphic rock may look different
True
Name a foliated low grade metamorphic rock that is fine grained and has flat breakage (slaty cleavage)
A) slate
Name a foliated low grade metamorphic rock that is fine grained, and has satin sheen
A) phyllite
Name a foliated intermediate grade metamorphic rock that is course grained, and has an alignment of platy/elongate minerals
B) schist
Name a foliated metamorphic rock that is high grade metamorphic that is course grained and banded in appearance
A) gneiss
Name a non foliated metamorphic rock that is composed of dominant quartz mineral and forms from metamorphosing Sandstone (SS) prolitith.
A) quartzite
Name a non foliated metamorphic rock that is composed of dominantly of calcite or dolomite mineral and forms from metamorphosing limestone or dolostone protolith
A) marble
Name a metamorphic rock that is composed of partially decayed plants in swamps
C) anthracite coal
Why does anthracite coal burn the highest of the coals?
Anthracite coal burns the highest of the coal's because it has more carbon and less impurities.
In order to produce anthracite coal they have to be anywhere in the ____ having more _____ pressure then it has _____ pressure.
A) crust; lithostatic; differential
True or False; if False restate to be true
Minerals grow in the direction of more pressure
False
Minerals grow in the direction of less pressure
What is a protolith?
A protolith is the original rock of a metamorphic rock
True or False; if False restate to be true
Quartz is the most resist to weathering
True
What is the most common dolomitic marble?
Calcite
Name an example of regional metamorphism
continental plate colliding with continental plate
Name an example of contact metamorphism
Oceanic plate colliding with continental plate or hotspot
Name an example of dynamic metamorphism
Along fault lines
Name an example of hydro-thermal metamorphism
Oceanic ridges
Name an example of burial metamorphism
The orogeny of mountains; rocks coming down off the mountain sides
Cataclastic metamorphism (also called dynamic metamorphism) forms due to
D) high pressure along faults
Contact metamorphism would be LEAST LIKELY to occur at which of the following plate settings?
A) continent-continent collision zone
Lithostatic pressure is
D) due to the weight of the overlying rock and a uniform pressure
Marble forms from metamorphism of _________.
C) limestone
Metamorphism of rocks adjacent to an igneous intrusion is _____.
D) contact metamorphism
Rocks metamorphosed during the Grenville Orogeny about 1.1-1.3 billion years ago are exposed in the Adirondack Mountains of New York and ____.
A) in the Hill Country of Texas
Which of the following is not a foliated metamorphic rock?
A) quartzite
Which of the following statements about metamorphism is NOT correct?
A) Metamorphism requires that there be a differential pressure in the crust.
Which type of metamorphic rock has relatively smooth breakage surfaces?
B) slate
Which type of metamorphism commonly occurs along oceanic ridges?
C) hydrothermal metamorphism
What does metamorphic grade refer too?
Metamorphic grade refers to the general pressure and temperature conditions
What is a mylonite?
A mylonite is a highly strained rock produced as a result of cataclastic metamorphism
How are foliated rocks classified?
Foliated rocks are classified based on type of foliation
How are non-foliated rocks classified?
Non-foliated rocks are classified based on mineral composition
Name a non-foliated rock that refers to rocks with minerals that typically forms from contact metamorhphism
D) hornfels
What is the metamorphic facies concept?
Metamorphic facies concept – the mineral composition of a metamorphic rock reflects the rock type of the protolith (the original rock that was metamorphosed) AND metamorphic grade. This concept helps geologists determine things like what the P,T of metamorphism were and what the protolith was. That information can help answer questions like – how deeply were rocks buried (i.e. how tall was an ancient mountain belt), and what type(s) of environment(s) or plate boundaries existed prior to or during metamorphism.