Geochemistry Flashcards
study of the nature and distribution of chemical elements in rocks and minerals; the application of
basic chemistry to earth sciences
Geochemistry
GEOCHEMISTRY was first coined or used as a term by
Christian Friedrich Schonbein
the first geochemist in the modern sense of the world
Frank W. Clarke
Book of Frank W. Clarke
The data of geochemistry
correlated the mineral formation and structure to its
chemical composition
Victor M. Goldschmidt
Father of Modern and Crystal Chemistry
Victor M. Goldschmidt
rock loving mineral
Lithophile
ore loving mineral
Chalcophile
iron loving mineral
Siderophile
gas loving mineral
Atmophile
a model of the evolution of the universe that
postulates its origin from a hot, dense mass that expanded rapidly and cooled
Bigbang Theory
fundamental composition of Bigbang Theory
Quark soup
is the energy of radiation produced at a specific wavelength when the universe was at temperatures
greater than about 3000oK
Cosmic Microwave Radiation
spectral lines of light emitted by distant galaxies
Red shift
“hierarchy of heavenly bodies”
➢Cluster of galaxies ➢Galaxies ➢Stars, pulsars, and black holes ➢Planets ➢Satellites ➢Comets ➢Asteroids ➢Meteoroids ➢Dust particles ➢Molecules ➢Atoms of H and He
produced by contraction of interstellar gases resulting in increase in temperature; energy production by H fusion becomes possible and thus produces the star.
Main Sequence Stars
high luminosity and high temperature stars
Blue Giant
stars less massive than the sun
Red Dwarf
bigger than the sun and is formed by depletion of H in the core during the main phase; the energy production shifted from the core to the outer shell.
Red Giant
end stage of stellar evolution; contraction leads to the
increase in core temperature and eventually explodes to
form the supernova; the star cycle begins again
Pulsar, White Dwarf, Black Hole
the theory that explains the complexation of material from the simple structure of H and deuterium
Nucleosynthesis
diffuse mass of interstellar gas and dust.
Solar Nebula
condensates accreted to form larger bodies as a result of selective adhesion caused by electrostatic and magnetic forces.
Planetisimal
volatile-rich planetisimals composed of water,
ammonia, methane, and other volatiles
Cometisimal
chunks of rock from space that land on Earth
Meteorite
Minerals in meteorite
KPOP
Kamacite
Pyroxene
Olivine
Plagioclase
Bronzite is what group of mineral?
Pyroxene
Predominantly Ni-Fe alloys Minor amounts of other minerals such as troilite (FeS) Types classified according to % Ni:
Iron Meteorite
has Widmanstatten structure, exsolution feature formed by slow cooling
Octahedrite
Minerals found in Iron Meteorite
HAO
Hexahedrite
Ataxite
Octahedrite
Chiefly silicates, mostly ferromagnesian Up to 1/4 metallic Ni-Fe Types
Stone Meteorite
Contain chondrules
Chondrite
Most important chondrite
Carbonaceous Chondrite
- Have same composition as Sun’s atmosphere
- High content of volatiles
Chondrite
- Same composition as terrestrial mafic and ultramafic rocks
- Most achondrites are breccias
Achondrite
Equal amounts of silicates and Ni-Fe
alloys Many are crystallized silicates which have been
brecciated, then invaded by metallic and sulfide melts
Stony Meteorite
no chondrules
Achondrite
Pallasite is what type of mineral?
Olivine
What minerals are found in Stony Meteorite?
Pallasite
Mesosiderite
protons are _____ more massive than electrons.
1825 times
denotes any of the more than 1300 different atomic forms characterized by a distinct combination of protons and neutrons; only about 270 of which are stable
Nuclide
composed of positively charged protons and neutrons,
particles of nearly equal mass but of zero charge
Nucleus
Elements of even atomic number are more abundant than those of odd atomic number on either side
Oddo-Harkins Rule
play the crucial role of overcoming
the repulsive forces between protons, thus binding
the nucleus to a tight structural unit
Neutron
refers to the number of proton in an atom of an element
Atomic Number
number of protons plus the number of neutrons
in an atom of an element
Atomic Mass
the sum of the masses of its naturally occurring isotopes weighted in accordance with their abundances
Atomic Weight
variation in atomic masses due to differences in the number neutrons of an element
Isotope
– nuclides having constant mass number but a different
atomic number
Isotone
nuclides having the same atomic mass but different
neutron number and atomic number
Isobar
a region surrounding the nucleus occupied by electrons
having approximately the same energy.
Electron Shell
Charge deficiencies that result from the substitution of
ions of unequal charges must be compensated by a
second substitution involving an ion having a different
charge
Coupled Substitution
An alternative to coupled substitution in which ions
are attached on the charged surfaces of small ions;
usually displayed by the clay minerals.
Adsorption
This occurs when the minor element has the same
charge and a similar atomic radius as the major
element it is replacing
Camouflage
This takes place when a minor element enters a crystal preferentially because it has a higher ionic potential than the ions of the major element
Capture
This involves the entry of a foreign ion that has a lower ionic potential that the major ion because it has either a lower charge or a larger radius, or both; the extent to which ions are admitted into a particular lattice site
decreases as the difference in radii of competing ions increases
Admission
possesses lowest potential energy possible for the mineral
Stable
possesses the highest potential energy
Unstable
requires an energy hurdle to put in the most stable form or of
lower potential energy
Metastable
reveals or shows the ranges of stability in
pressure-temperature space
Phase Diagram
areas representing the range of applied
pressure and temperature in which a mineral may exist in its stable form
Stability Fields
the line separating the various stability
fields and defines a restricted set of circumstance under
which the separated phase coexist in equilibrium
Phase Boundary
energy required for transformation to take place and is represented by the height of the energy hurdle
Activation Energy
– concerned on the free energy changes
associated with chemical equilibrium between phases, and provides the tools for working out which mineral
assemblages will be stable under which conditions.
Thermodynamics
deals with the mechanics of the reactions that lead to equilibrium, and the rates at which they occur
Chemical Kinetics
– a part of the universe which we wish to confine attention or whose properties are under consideration; the system is separated from its surroundings by a boundary whose properties can be defined
System
– one that is free to exchange both matter and energy
with the surroundings
Open System
– a part or parts of a system occupying a specific volume
and having uniform physical and chemical characteristics which distinguishes it form all other parts of the system
Phase
one that is sealed with respect to the transfer of
matter, but that can still exchange energies with its surroundings
Closed System
– comprise the minimum number of chemical species required to specify completely the compositions of all the phases present
Components
all parts of the system have the same temperature;
there is no net transfer of heat
Thermal Equilibrium
one that is capable of exchanging neither mass or
energy with its surroundings
Isolate System
– the diffusion rates of an element in and out of the
crystal are unequal; there will be a net change of composition of each phase with time.
Disequilibrium
the distribution of components among the phases of
a system has become constant, showing no net change with time
Chemical Equilibrium
for every element present the flux of atoms across the
crystal boundary is the same in both directions resulting in zero net flow, and no change of composition in time
Equilibrium
a formula which expresses the number of phases that can coexist in mutual equilibrium in terms of the
number of components in the system
Phase Rule
An Al2SiO5 that forms at low temperature
Kyanite
means that the three phase equilibrium
assemblage completely constrains the state of the system to a particular combination of P and T
Invariant
one degree of freedom indicates that the state of the
system is only unconstrained in one direction which is along the phase boundary
Univariant
the pressure and the temperature can vary independently without upsetting the equilibrium phase
assemblage
Divariant
is the locus of temperatures below which a given
substance is completely solid
Solidus
The temperature which partial melting starts
Solidus
The temperature above which a material is completely liquid
Liquidus
the point on a phase diagram where the maximum number of allowable phases are in equilibrium
Eutectic Point
- A phase that has a composition intermediate between two other phases.
Intermediate Compound
Temperature where crystallization occurs
Liquidus
The point on a phase diagram where a reaction takes place between a previously precipitated phase
and the liquid to produce a new solid phase
Peritectic Point
melting wherein a phase melts to a liquid with the same composition as the solid
Congruent Melting
are usually measured in percentage and are commonly above 1% of the chemical composition of the material
Major Elements
melting wherein a phase melts to a liquid with a composition different from the solid and produces a solid of different composition to the original solid.
Incongruent Melting
are elements that occur in such small concentrations that they do not change the essence of what a material is. usually < 0.1%
Trace Element
are everything in between. Technically, this means things between 1% and 0.1%.
Minor Element
Useful for rocks in mobile belts that are no longer recognizably in their original setting
Trace Element
ions that do not fit into the structure of the rock-forming minerals or minerals precipitating in the magma
Incompatible Elements
Are not necessarily primitive nor primary but
where other magmas derived
Parental Magma
ions easily
accommodated in the mineral structure.
Compatible Elements
are the first magma derived from primitive magma.
Primary Magma
magma derived from the mantle
Primitive Magma
mineral found in fertile unaltered magma
Lherzolite
mineral found in a most evolved magma
Dunite
separates the subalkaline from the alkaline fields at low P
Thermal Divide
What element is being consumed by plagioclase that results to a negative anomaly?
Europium
High concentration indicate a mantle source, limited fractionation
Cr, Ni, Co
Implies an enriched source or extensive liquid evolution
Zr, Hf
Found in subduction-related melts, typically low conc
Nb, Ta
Indicator of Pxn fractionation
Sc
Substitutes for Ca in plagioclase
Sr
Used to study melting and crystallization
Ru, Rh, Re. Pd, Pt, Os, Ir
Used in modeling source characteristics and liquid evolution
REE
Strongly partitioned in Garnet and Amp
Y
is a non-destructive analytical technique used to
determine the elemental composition of materials
XRF
is the primary, non-destructive tool for identifying
and quantifying the mineralogy of crystalline compounds in rocks
XRD
s a spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state.
Atomic Absorption Spectometry
an analytical
technique used for elemental determinations
Inductively Coupled Plasma Mass Spectrometry
The time taken for the radioactivity of a specified isotope to fall to half its original value.
Half Life
