XXIX. Geochemistry Flashcards by Catherine Themis

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

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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

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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

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Elements that bond with oxygen and prefer silicate minerals (e.g., Si, Al, K). Common in the Earth’s crust.

Lithophile (rock-loving)

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Elements that dissolve in molten iron and tend to concentrate in the core (e.g., Fe, Ni, Co).

Siderophile (iron-loving

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Elements that bond with sulfur and form sulfide minerals (e.g., Cu, Pb, Zn). Found in ore deposits.

Chalcophile (ore-loving)

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Volatile elements that prefer the gaseous phase or occur in the atmosphere (e.g., H, N, noble gases).

Atmophile (gas-loving)

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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

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The study of the chemical composition of matter in the universe and the processes that led to these compositions.

Cosmochemistry

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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

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explains the origin of the universe

The Big Bang Theory

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explains the origin of the Moon

Giant Impact Hypothesis

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refers to a period of intense meteorite impacts after planet formation

Late Heavy Bombardment

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Name the planets (closest to farthest from the sun).

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

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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

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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

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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

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_____ 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

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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

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mainly made up of silicates (e.g. olivine, pyroxene, plagioclase)
make up over 90% of all meteorites

Stones (Chondrites, Achondrites, Carbonaceous Chondrites)

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abundance of both silicate minerals and iron-nickel alloy

Stony Irons (Pallasites, Siderophyre, Lodranite, Mesosiderites)

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consist mainly of iron-nickel alloy

Irons (Hexahedrites, Octahedrites, Ataxites)

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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

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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

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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

10. 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)

XXIX. Geochemistry Flashcards

(60 cards)