XXIX. Geochemistry Flashcards
The term “geochemistry” was first coined in 1838 by this chemistry professor of the University of Basel in Switzerland.
A. Dmitri Ivanovich Mendeleev
B. Gustav Kirchhoff
C. Victor M. Goldschmidt
D. Christian Friedrich Schönbein
D. Christian Friedrich Schönbein
He is considered as the “father of geochemistry” and is largely known for his
determination of the composition of the Earth’s crust.
A. Victor M. Goldschmidt
B. Christian Friedrich Schönbein
C. Norman Levi Bowen
D. Frank W. Clarke
D. Frank W. Clarke
For his extensive work on crystal structures of minerals using x-ray diffraction, _____ is often called the “father of modern geochemistry and crystal chemistry”.
A. Victor M. Goldschmidt
B. Christian Friedrich Schönbein
C. Norman Levi Bowen
D. Frank W. Clarke
A. Victor M. Goldschmidt
Elements that bond with oxygen and prefer silicate minerals (e.g., Si, Al, K). Common in the Earth’s crust.
Lithophile (rock-loving)
Elements that dissolve in molten iron and tend to concentrate in the core (e.g., Fe, Ni, Co).
Siderophile (iron-loving
Elements that bond with sulfur and form sulfide minerals (e.g., Cu, Pb, Zn). Found in ore deposits.
Chalcophile (ore-loving)
Volatile elements that prefer the gaseous phase or occur in the atmosphere (e.g., H, N, noble gases).
Atmophile (gas-loving)
Which of the following best explains the origin of our solar system?
A. The Big Bang Theory
B. The Nebular Hypothesis
C. Giant Impact Hypothesis
D. Late Heavy Bombardment
B. The Nebular Hypothesis
The study of the chemical composition of matter in the universe and the processes that led to these compositions.
Cosmochemistry
It proposes that the solar system formed about 4.6 billion years ago from a giant rotating cloud of gas and dust (a nebula). Gravity caused the nebula to collapse, forming the Sun at its center and planets from the surrounding material.
The Nebular Hypothesis
explains the origin of the universe
The Big Bang Theory
explains the origin of the Moon
Giant Impact Hypothesis
refers to a period of intense meteorite impacts after planet formation
Late Heavy Bombardment
Name the planets (closest to farthest from the sun).
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
What are the two types of planets?
Terrestrial planets – small, rocky planets: Mercury, Venus, Earth, Mars
Jovian planets (Gas Giants/Ice Giants) – large, gas-rich planets: Jupiter, Saturn, Uranus, Neptune
A star’s energy is generated through nucleosynthesis. This usually starts with the fusion of _____.
A. He to N
B. N to He
C. H to He
D. He to H
C. H to He
The stars energy come from the fusion of light elements into heavier elements; convert hydrogen to helium. Most of the elements in the universe heavier than He were created in the stars in a process called _________.
nucleosynthesis
_____ are often considered as the most primitive meteorites and are thought to be representative of the initial material from which the solar system was also derived from.
A. Carbonaceous chondrites
B. Ordinary chondrites
C. Achondrites
D. Stony irons
A. Carbonaceous chondrites
a solid piece of debris from outer space—often originating from the asteroid belt—that survives its fiery passage through Earth’s atmosphere and impacts the surface, varying in size and providing crucial insights into the formation and early history of planetary bodies
meteorite
- mainly made up of silicates (e.g. olivine, pyroxene, plagioclase)
- make up over 90% of all meteorites
Stones (Chondrites, Achondrites, Carbonaceous Chondrites)
abundance of both silicate minerals and iron-nickel alloy
Stony Irons (Pallasites, Siderophyre, Lodranite, Mesosiderites)
consist mainly of iron-nickel alloy
Irons (Hexahedrites, Octahedrites, Ataxites)
found in December 1984 in Antarctica; Ejected from Mars about 17 million years ago and spent 11,000 years in or on the Antarctic ice sheets
ALH84001 meteorite
In the periodic table of elements, the elements are arranged in order of _____.
A. Decreasing atomic weight
B. Increasing volume
C. Increasing atomic number
D. Decreasing atomic number
C. Increasing atomic number
pure chemical substance consisting of one type of atom distinguished by its atomic number
Element
consist of a nucleus of protons and neutrons surrounded by electrons
Atom
A maximum of 2 electrons can occupy an orbital and the 2 electrons must spin in the opposite directions.
Pauli exclusion principle
One electron goes into each of these orbitals before two electrons can be placed in any of them.
Hund’s Rule
_____ is a type of chemical bonding which involves the sharing of electrons between two non-metals that have similar electronegativities.
A. Covalent bond
B. Ionic bond
C. Van der Waals bond
D. James bond
A. Covalent bond
The silicon-oxygen tetrahedron is the basic unit for building crystal structures or silicate minerals. What is its net change?
A. SiO4+2
B. SiO4-2
C. SiO4+4
D. SiO4-4
B. SiO4-2
- Two substances are called isomorphous if they have similar structures but different chemical formulas. A good example of this is the pair _____.
A. Siderite and calcite
B. Calcite and aragonite
C. Pyrite and marcasite
D. Pyrite and chalcopyrite
C. Pyrite and marcasite
The two end members of the olivine solid solution series are forsterite (Mg2SiO4) and
fayalite (_____).
A. MnSiO4
B. CaMgSiO4
C. Fe2SiO4
D. CaFeSiO4
C. Fe2SiO4
The ability of different elements to occupy the same lattice position in a particular
crystal is called _____.
A. Isomorphism
B. Inclusion
C. Polymorphism
D. Diadochy
D. Diadochy
Lithophiles are elements that remain or close to the surface. They combine readily with oxygen, forming compounds that do not sink into the core. Which of the following is not a lithophile element?
A. U
B. Zn
C. Sc
D. V
A. U
_____ are elements which tend to sink to the core because they dissolve readily in iron either as solid solutions or in the molten state.
A. Lithophiles
B. Chalcophiles
C. Siderophiles
D. Atmophiles
C. Siderophiles
The _____ marks the temperature at which crystallization reaches completion and
the melt ceases to exist.
A. Solidus
B. Liquidus
C. Eutectic point
D. Cotectic boundary
A. Solidus
In a binary phase diagram with diopside and anorthite as chemical components, the melt can coexist with crystals of both diopside and anorthite only at the _____.
A. Solidus
B. Liquidus
C. Eutectic point
D. Cotectic boundary
C. Eutectic point
As crystallization advances, the number of soild phases _____.
A. Increases
B. Decreases
C. Remains the same
D. Fluctuates
A. Increases
Trace element abundances are often expressed as ppm. As a rule of thumb, 1 wt%
= _____.
A. 10 ppm
B. 100 ppm
C. 1000 ppm
D. 10,000 ppm
C. 1000 ppm
> 1.0 wt%
MAJOR
0.1-1.0 wt%
MINOR
< 0.1 wt%
TRACE
Which of the following is not a major oxide in most igneous rocks?
A. MnO
B. MgO
C. Al2O3
D. CaO
A. MnO
SiO2 Al2O3 FeO* MgO CaO Na2O K2O
Major elements
TiO2, H2O, MnO and P2O5
Minor elements
H2O is the most common volatile constituent in most rocks and minerals. When
present as OH-bonded in hydrous minerals such as amphiboles and micas, H2O+ is
sometimes referred to as _____.
A. Structural water
B. Mineralized water
C. Meteoric water
D. Pure water
A. Structural water
Loss of ignition (LOI) is the weight loss that occurs when the powdered sample is
heated to _____, at which point all the remaining volatiles are released.
A. 500°C
B. 600°C
C. 700°C
D. 800°C
B. 600°C
On the basis of increasing MgO, which is the most plausible succession of igneous
rocks?
A. Rhyolite > basalt > andesite > peridotite
B. Peridotite > basalt > andesite > rhyolite
C. Rhyolite > andesite > basalt > peridotite
D. Basalt > peridotite > rhyolite > andesite
B. Peridotite > basalt > andesite > rhyolite
The commonly observed mafic to silicic trend in igneous rocks is characterized by _____.
A. Decrease in SiO2 with decrease in MgO
B. Increase in SiO2 with decrease in MgO
C. Increase in SiO2 with increase in MgO
D. Decrease in SiO2 with increase in MgO
B. Increase in SiO2 with decrease in MgO
A Harker diagram is a binary plot typically showing _____.
A. MgO vs FeO
B. Al2O3 vs CaO
C. MgO vs NaO
D. SiO2 vs FeO
D. SiO2 vs FeO
In a single magmatic suite, parental magmas should have _____ than evolved
magmas.
A. Lower SiO2 and higher FeO content
B. Higher SiO2 and lower FeO content
C. Lower SiO2 and higher NaO content
D. Higher SiO2 and lower NaO content
A. Lower SiO2 and higher FeO content
According to the total alkalis vs silica (TAS) diagram for volcanic rocks, trachyte
has _____ than rhyolite.
A. Higher SiO2 and lower alkali content
B. Higher SiO2 and higher alkali content
C. Lower SiO2 and lower alkali content
D. Lower SiO2 and higher alkali content
D. Lower SiO2 and higher alkali content
In general, tholeiitic magmas have _____ than calc-alkaline magmas.
A. Lower FeO
B. Higher FeO
C. Higher alkali content
D. Lower alkali content
B. Higher FeO
The partition coefficient (KD) determines the compatibility of elements to a particular
solid. Incompatible elements often have _____.
A. KD > 1
B. KD < 1
C. KD = 1
D. KD = 0
B. KD < 1
What technique is often used to determine the chemical composition of a specific
mineral?
A. EPMA
B. XRD
C. XRF
D. ICPMS
E. SEM
A. EPMA (Electron Probe Micro-Analysis)
analyze mineral grains on the scales of microns in minutes
EPMA (Electron Probe Micro-Analysis)
examine physico-chemical makeup of unknown solids
X-ray diffraction (XRD)
major and trace element analyses of bulk rocks, minerals, sediments and fluids
X-ray fluorescence (XRF)
trace compositions; capable of detecting metals and several non-metals at very low
concentrations
Inductively coupled plasma mass spectrometry (ICPMS)
generate high-resolution images of shapes/objects (SEI) and to show spatial variations in chemical compositions
Scanning Electron Microscope (SEM)
