igneous petrology unit of geoscience 201
3rd order birefrigence
calcite
equilibrium crystallization metlting type of system
closed system
diopside
clynopyrexine
granitoid rocks
coirse grained plutionic rocks composed pre-dominately of feldspar (plagioclase and potassium) and quartz
granites
composed primarily of quartz and feldspar, with mioner hornblende and or biotite
is the lithospheres geotherm conductive or convective
conductive (high dT/dP)
is the asthenosphere geotherm conductive or convective
convective (low dT/dP)
orogenic granitoids
crystal thickening associated with mountain building
phenocrysts
crystals thats much larger than its surroundings
how do theolites form predominately
decomposition
at oceanic plate
decreasing pressure, increase temp
when f=2, _____ part of phase diagram
divariant
davis Clapeyron equation
dp/dt = change in s over change in v
latent heat of fusion
energy needed to melt rocks
composition of liquid at start _____ composition of solid at end
equals
how basalts form differently
evolve via fractional crystallization as separate series along different paths
reticulite
extreme form of pumis, lava froth
condensed phase rule
f=c-p+1
anorithe
feldspar
plutonic rocks composed predominately of
feldspar and quartz
polarization
filtering of light to vibrate in one plane
xenolith
foreign rock
i-type
form through extensive fractional crystallization
s-type
form through partial melting (anatexis) of meta-sedimentary rocks derived from surface processes
when the angle of incidence equals the critical angle, the angle of refraction
is 90 degrees
intrusive igneous rocks
magmas that cool slowly and completely beneath the surface without ever erupting -large interlocking crystals and absence of a matrix
anorogenic
not associate wiht mountain building
Ocean Island Basalts
occur not at plate boundaries but at "hot spots" that are located over a deep mantle source -melt fraction is quite small in OIB
stokes law
rate of crystal settling is determined by physical properties of magma crystals
lever rule
relative proportions of liquid crystals at any given temp can be determined form the isopleth
fractional crystallization/melting
removal of solid from liquid
becke line
result of total internal reflection
mafic composition
rich in mg, fe, lower in si
unstable equilibrium (on a graph)
right before true minimum
pressure distribution is controlled by _____ and _____
rock density and depth
migmatite
rock that has almost melted and is composed of intermingled melt and residual components
pahoehoe
runny viscous magma, smooth
moho
separates crust and mantle
basalt magmas normally form
shield volcanoes
uniary phase diagram
single component in a diagram
pele's hair
small volcanic glass happens from explosive eruptions and cool air
higher pressure favors ___ volume (smaller, larger)
smaller
component
smallest number of chemical constituents required to completely describe a system ex) Mgo, Sio2, H2o
interstitial crystallization sequence
solid of mineral deposit in which the minerals fill the pores of the host
mantle convection
stirs the asthenosphere
______ (system/phase) are made of _______ (system/phase); _____ (system/phase) are made up of components
system, phases, phases,
geotherm
temperature as a function of depth
equilibrium (on a graph)
true minimum
when f=1, ____ lines
univariant
non-polarized light
vibrates in all directions
plane-polarized light
vibrates only in one direction
alkaline basalts
(high na, ca, k) formed at subduction zones
calc-alkaline basalts
(high xfe3+) formed at subductin zones
theolite basalts
(low Na, low fe) generated at mid ocean ridges, oceanic islands, and subduction zones
when f=0, __ points of freedom, cannot change T/P
0
how do granites form? (two types)
1) melt pre-existing silica rock (continental crust) 2)fractional crystallization of maifc melt both processes will produce sio2 rich melts around the cotectics and eutectic minima in the system
birefringence formula
B= |n1-n2|
partition coefficient
D^sol/melt=csol/cmelt
Gibbs Phase Rule
F = C - P + 2
what type of magma is calc-alkaline basalts
Island- arc basalts
when the angle of incidence is greater than or equal to the critical angle,
all the light undergoes reflection
angle of incidence
a light ray strikes a surface at a given angle
isopleth
a line of constant composition
pleochroism
a mineral in thin section can change color depending o angle of rotation
metastable
a non equilibrium state that may persist for a very long time
intensive
a physical quality whose value does not depend on amount of substance for which its measured (density, hardness, temp, pressure, color)
latent heat
additional energy in rock that doesnt account for a temperature increase
differentiation
any process that changes the composition of a magma
liquid line of descent
as cooling proceeds liquid composition follows the liquids towards the eutectic
melting of a solid
as melting proceeds, liquid composition follows the liquidius away from the eutectic
orogenic
associated with mountain building
limu o pele
forms by interaction of sheets of basaltic lava and seawater
pillow
forms on eruption of basalt in the sea- reacts directly with seawater (expected at mid-ocean ridges)
1st order birefringence
garnet, quartz, hornblende
vesicles
gas bubbles that form pore spaces
rhyolites
granitic magmas that erupt at the surface to form volcanic rocks
element is compatible if d ___ 1
greater than
matrix
groundmass of a rock
unary systems
h2o, al2sio2, sio2
invariant points
have specific and unique coordinates
columnar jointing
hexagonal columns that form when basaltic lava flow cools
fluid fluxing
important in subduction zones and other settings
isotropic minerals
in isometric system and the speed of light is the same in all directions
when mantle plumes occur does temp increase or decrease
increase
3 ways to melt mantle
increase the temp, decrease the pressure, add volatiles to lower solidus
for stokes law when volume increases, change in pressure ___ radius ____, viscosity of liquid ____
increase, increase, decrease
the concentration of an incompatible element ___ as a magma evolves by fractional crystallization
increases
factors affecting sequence and degree of crystallization
initial comp of magma, pressure changes as magma rise, and cooling
anorogenic granitoids
intraplate setting asssociate with plumes or rifts
2nd order birefringence
kyanite
degrees of freedom (f)
largest number of independent intensive thermodynamic parameters (such t, p or x)
aa
lava flows, blocky nature
element is incompatible if d ___1
less than
what colors are in periodotite and what mineral is it
light green-shows olivine , and darker grains are clynopyrexine
eutectic
liquid transforms to two solid phases
fractional crystallization
liquid/solid removed from each other, cannot thermodynamically communicate composition (changed with temperature)
metastable equilibrium (on a graph)
local minimum
quartz
low relief
amphiboles relief
low to high
granitoids that are dark have __ sio2 while light have ___sio2
lower, higher
constructive wave interference
makes amplitude bigger (in phase)
destructive wave interface
makes amplitude smaller (out of phase)
diapir
mantle wedge
volatile-induced melting
melting occurs in response to addition of fluid
adiabatic melting
melting occurs in response to pressure
mid ocean ridge basalts (MORB)
melting occurs in response to pressure drop with no change in temp ----> adiabatic melting - theolitic basalt
in what type of crystals does inclined extiction occur
monoclinc crystals
the asthenosphere has ___ ___ than the lithosphere
more melt, this allows it to flow because it weakens
snells law
n1sinθ1 = n2sinθ2. When n2>n1, light bends toward the normal. When n2<n1, light bends away from the normal
ratio of speed of light in vacuum to the speed in a given material
n=Vv/v
isotropic minerals
no change in light as the mineral goes around
fractional crystallization/melting type of system
open system
what two settings do plutoinc rocks form in
orogenic or anorogenic
in what type of crystals does parallel extiction occur
orthohombic crystals
lithospheric pressure
p=pgh
anatexis
partial melting
what do basalts come from
partial melting of the mantle
what rock dominates the mantle (ultramafic rock)
peridotite
phase
physically distinct, mechanically separable part of a system ex) fosterite, quartz, ice, water
mechanics
potential energy minimized
basalt
primary product in mantle melting - extrusive igneous rock made up of primarily of fine grained olivine, pyroxene, plagioclase, oxide
adiabatic
process where heat does not enter or leave system concerned
extensive
quality whose value depends on the amount of substance (mass, vol, gibbs energy, heat capacity, enthalphy
gravity settling
the differential motion of crystals and liquid under the influence of gravity due to their differences in density
retardation
thickness times birefringence - is the difference between peaks and the thickness of the mineral
relief
three- dimensional character or depth -determined by difference in refractive indices between two material
binary system
when two components are mixed, the melting point of the mixture is lower than the individual melting points of the components
lava fountain/cinder cone
where basalt erupts
percent crystals (lever rule)
xz/xy times 100
are granitoids intrusive?
yes
can equilibrium state change with temp
yes
does equilibrium depend on kinetics
yes
percent liquid (lever rule)
zy/xy times 100
stokes law equation
ν = 2r^2 (ρ1 - ρ2) g/9η0 where: ν = velocity of settling r = particle radius ρ1 = particle density ρ2 = medium density g = gravitational acceleration η0 = medium viscosity