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