earth materials Flashcards
It is the transition zone between
SIAL (silica aluminum), upper crust and SIMA
(silica magnesim ), lower crust
Conrad Discontinuity
discontinuities in the layers of earth
co
mo
re
gu
le
_________ are composed largely of dark colored mafic rocks enriched in _____ of _____, ____, and _____ relative to average crust
oceanic crust ; oxides ; iron, magnesum, and calcium
Composed largely of dark colored, mafic rocks enriched in oxides of magnesium, iron and calcium
( FeO and CaO) relative to average crust
oceanic crust
thickness of oceanic crust (depth to moho)
5-7 km
under some oceanic islands, oceanic crust can extend its thickness up to:
18km
primary rocks found in oceanic crust
basalt and gabbro
t or f: oceanic crust are older relative to the age of the earth
F (younger)
slices of ocean crust thrust onto continental margins
ophiolites
can be generalized as granitic in composition enriched in K2O, Na2O, and SiO2
continental crust
continental crust is enriched in oxides of:
Potassium, Sodium, and Silica
oldest well documented continental crust
4.03 Ga
from the northwest territories of canada
t or f: continental is thicker than oceanic crust
T
the great age of some continental crust results from its
buoyancy
silica composition of continental crust
approximately 60%
silica composition of oceanic crust
approx 50%
thickness of continental crust
30 km, under mountains is 80 km
age of oceanic crust
up to 180 Ma, 3.5% of earth’s history
age of continental crust
up to 4000Ma, 85-90% of earth’s history
t or f: oceanic crust have relatively lower surface elevation than oceanic crust
t
oceanic crust are mostly submerged _____sea level while continental crust are mostly emergent _____ seas level
below ; above
thickness of earth’s mantle
2900 km
radius of the earth
6370 km
earth’s mantle constitutes how many percent of earth’s volume
approx 83%
silica composition of earth’s mantle
40-45%
the earth’s mantle has an _____ composition
ultrabasic
sublayers of earth’s mantle
upper mantle and transition zone
lower mantle
MgO content of mantle
30-40%
depth of low velocity zone
100-250 km
marks the contact between strong lithosphere and weak asthenosphere
low velocity zone
the uppermost part of the mantle and the crust together constitute the relatively rigid _____
lithosphere
the asthenosphere is more _____ and _____, rather than rupturing when subjected to stress
plastic ; flows slowly
lithosphere is strong enough to _____ in response to stress
rupture
minerals found in transition zone
ringwoodite and garnet
minerals found @660km depth
perovskite and periclase
minerals found @410km depth
olivine, wadleysite
major minerals found in mesosphere
perovskite and periclase;
ilmenite;
ferrite;
stishovite;
magnesiowustite;
complex zone near the core-mantle boundary, where anomalous seismic signals are common
D” layer
our knowledge of the deep mantle continues to expand largely based on ________ deep within the earth
anomalous seismic signals
D’’ discontinuity ranges from
130-340 km
heat sources in the earth
- residual heat from formation
- frictional heat
- decay of radioactive elements
these sporadic ULVZ may be related to the formation of _______within the lower mantle
deep mantle plumes
percent composition of iron in earth’s core
approx 85%
percent composition of nickel in earth’s core
5 %
density of outer core
10-12 g/cm^3
density of inner core
appox 13g/cm^3
refers to the non-uniform seismic velocities in the core
seismic anisotropy
amount of heat that can arise from accretion of small bodies, forming proto-earth
10,000 kelvins
heat produced by descent of iron-rich materials
2,000 kelvins
long-lived radioactive isotopes
235U, 238U, 232Th, and 40K
goldschmidt classifications
lithophile-rock loving
siderophile - iron loving
chalcophile - sulfur loving
atmophile - gas loving
what does HREE/LREE stand for?
Heavy Rare Earth Elements;
Light Rare Earth Elements
what does LILEs stand for?
Large Ion Lithophile Elements
what does LFSEs and HFSEs stand for?
Low Field Strength Elements ; High Field Strength Elements
the substance of which any physical object is composed of
matter
controlling factors of state of matter
temperature and pressure
layers of electrons that orbit around the nucleus are called
orbitals or energy-level shells
an atom that has gained or lost electron
ion
smallest particle that defines an element
atoms
consists of elements that combine in a specific ratio
chemical compound
covalent bonds have electronegativity of
less than 1.68
ionic bonds have electronegativity of
greater than 1.68
4 types of bonding
covalent
ionic
metallic
Van der Waals
very weak bonding
Van der Waals Bonding
what is a mineral
Naturally occuring
inorganic
homoenous solid
definite chemical composition
crystalline structure
most abundant silica group
feldspar (plagioclase) 39%
abundance of quartz
12%
arrange silica in terms on increasing abundance
plag
ortho
quartz
pyroxene
(non silicates)
amphibole
mica
clays
other silicates
involves circulation and exchange of elements and minerals within the ecosphere and its environment
biogeochemical cycle
t or f: asthenosphere is solid but mobile
T
depth of transition zone
410-660km
depth of upper mantle from the crust
410km
depth of lower mantle from the crust
660km
depth of outer core from the surface
2900km
depth of inner core from the surface
5150
it is a strong rigid layer
lithosphere
layers of ophiolite
layer 1 - sediments
layer 2 - pillow basalts and sheeted dikes
layer 3 - gabbro
layer 4 - layered ultramafic rocks
depth of asthenosphere
100-660
smallest quantity of a compound
molecule
4 types of bonding
covalent
ionic
metallic
Van der Waals
element abundances in the crust
46.6
27.7
8.1
5.0
3.6
2.8
2.6
2.1
