Rock Cycle/Igneous Flashcards
What is a rock?
Naturally occurring solid compound made up of an aggregate of minerals or a body of glass
What is an igneous rock?
Rocks that form from the freezing of melt (magma/lava)
What are sedimentary rocks?
Grains or other pieces of hard rock get glued together to form a coherent solid
What are metamorphic rocks?
A pre existing rock undergoes solid state change in response to the modification of its environment at depth
What is foliation?
Alignment of mineral grains
What can all 3 types of rocks do?
Produce all 3 types of each other
How do igneous rocks form? And what temps do they form?
From the freezing of melt and they form at around 650 to 1100 Celsius
What is it called when melt is below and above surface?
Below=magma above=lava
What are rocks when they form from the freezing of magma?
Intrusive Igneous Rocks
What are rocks when they form from the freezing of lava?
Extrusive Igneous Rocks
Where can melt form?
In special places where pre-existing rock is able to melt under high temps or pressure
Define Geotherm
Curved line on a graph that compares temp, pressure and depth
Describe decompression melting & what boundary is it associated with?
Temperature stays the same, pressure decreases (divergent boundaries)
Describe flux melting and what boundary is it associated with?
Hot rocks mix with volatile minerals causing melting to occur (Convergent boundaries)
Describe heat transfer melting
Heat from magma melts rocks around it
What helps us describe melts?
oxides
What are the 4 groups that we can describe igneous rocks in?
felsic, intermediate, magic, ultramafic
Describe felsic rocks
Light, highest amount of silica, 66-76% S.O
Describe intermediate rocks
Intermediate in color, 52-66% Silica
Describe mafic rocks
dark, 45-52% S.O
Describe ultramafic rocks
dark green in color, olivine, 38-45% S.O
What do the 4 compositions reflect in a rock
Where it came from
How much of a rock can melt to produce magma?
2-3%
What happens to rocks that form from partial melting?
they become more felsic
What would partial melting of an ultramafic source produce?
Mafic Igneous rocks
How could magmas become more mafic?
Heat transfer melting
How could melt become more mafic?
Iron+Mg rich materials enter
How does magma rise
magma becomes less dense
What happens when heavy rocks create pressure
magma is squeezed upwards
What is viscosity
Resistance to flow
Is felsic or mafic mage more viscous
felsic
What does viscosity depend on
temp, silica count, gas content
What happens if melt reaches the surface opposed to staying below
it cools faster
Describe faster vs slower cool
Faster: lava, extrusive,smaller crystals
Slower: Magma, Intrusive, Larger crystals
what factors control cooling
size and shape, depth, water
What are the first minerals to crystallize
mafic minerals (Iron-Mg-Rich)
What is a dike?
tabular intrusion that cross cuts pre existing layers
What is a sill?
tabular intrusion that is parallel to preexisting layers
What is a Laccolith?
Blister shaped intrusion that domes up overlying layers
What is a pluton?
Blob Shaped intrusion that extends for 10’s of kilometers
What is a batholith?
Blob Shaped intrusion that extends for 100’s of kilometers
