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Basics of Geochemistry
Abundance and speciation of the elements
Atoms
Abundance of the elements
Binding energy and elemental abundance
Abundance and form of the most abundant elements in Earth's continental crust
Cations and anions I: definitions
Cations and anions I: some geochemical realities
Cations and anions III: geochemical perspectives on ionic bonding
Cations and anions IV: the meaning of the superscripts
Variation in ionic radius between and within elements
Ionic Potential
Hardness and softness of ions I: an introduction
Hardness and softness of ions II: a spectrum across the periodic table
An Earth Scientist's Periodic Table of the Elements and Their Ions
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A bit of the Earth Scientist's Periodic Table of the Elements and Their Ions as a cross-section of the Earth
Categorizing cations
Categorizing anions
The importance of oxygen
The special situation of silicon
Redox chemistry
A brief review of redox chemistry
A periodic table of redox behavior
Common redox reactions in the oxidation of organic matter
Characterization of solutions by pH and Eh - the canonical view
Characterization of solutions by pH and Eh - a data-based view
Why oxidation commonly leads to acidification
Redox, ionic potential, and the behavior of cations
The geochemical redox conditions of some important elements
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Solutions and aqueous speciation of ions
Solutions, colloids, and suspensions
Speciation of cations in aqueous solution I
Speciation of cations in aqueous solution II
The power of polydentate ligands
Aqueous speciation of some hard cations across the periodic table
Variation in hydrated radius of ions
Aquoacidity of cations, in context
Activity and activity coefficients I
Activity and activity coefficients II: the logic of the Debye-Hückel equation
Activity and activity coefficients III: Ionic strength
Activity and activity coefficients IV: brines and γ > 1
Activity and activity coefficients V: from infinitely dilute solutions to brines
Activity and activity coefficients VI: Specific ion interaction
Activity and activity coefficients VII: Specific ion interaction constants
Silicon in aqueous solution
Conductivity as a proxy for total dissolved solids
The typical solutes of geochemical solutions (i.e., of natural waters)
Solutions, CO2, HCO3-, CO32- and CaCO3
Speciation of inorganic carbon in aqueous solution
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Variation in the dissociation constants of H2CO3 and HCO3- with temperature and salinity
PCO2 of atmospheres and pH and HCO3 - concentration of solutions
Carbonate equilibria in solutions exposed to the atmosphere I
Carbonate equilibria in solutions exposed to the atmosphere II
The carbon, and carbonate, cycle
Ca2+ and HCO3- concentrations in natural waters. Part I: a plot
Ca2+ and HCO3- concentrations in natural waters. Part Ia: an inset
Ca2+ and HCO3- concentrations in natural waters. Part Ib: an inset
Ca2+ and HCO3- concentrations in natural waters. Part II: observations
The reaction for equilibrium of CaCO3 with natural waters
Reactions for the dissolution of CaCO3
Reactions for the precipitation of CaCO3
Degassing of CO2 and precipitation of CaCO3
Adsorption of hydrated Mg2+ on calcite as an inhibitor of calcite growth
minerals" in the section on Carbonate minerals below.
The geochemistry of minerals
Growth and stability of minerals: nano-scale models
Surface features on a growing or dissolving crystal: terraces, kinks, and steps
Particle size and reactivity: It's all about edges and corners, rather than surface area
Size matters: why very small particles are very soluble
An explanation of the free-energy barrier to nucleation of crystals
Thermodynamics of nucleation of a new crystal vs. growth on an existing crystal
An explanation of the greater solubility of acicular, rather than equant, crystals
A thermodynamic perspective on Ostwald ripening
A thermodynamic perspective on Ostwald's Step Law
An illustrative example of Ostwald's Step Law: silica
An explanation of transport-limited and surface-reaction-limited crystal growth
How rate of solute supply can control crystal morphology
Nucleation vs. syntaxial overgrowth
Nucleation vs. syntaxial overgrowth I: an introduction
Nucleation vs. syntaxial overgrowth II: an example from a sandstone
Nucleation vs. syntaxial overgrowth III: an example from a sandy limestone
Nucleation vs. syntaxial overgrowth IVa: a stalagmite example
Nucleation vs. syntaxial overgrowth IVb: a stalagmite example in detail
Nucleation vs. syntaxial overgrowth V: an example in a Holocene limestone
Nucleation vs. syntaxial overgrowth VI: an example in a fractured limestone
Nucleation vs. syntaxial overgrowth VII: an example in a fractured dolostone
Phenomena at mineral surfaces
Sorption: adsorption and absorption
Surfaces, double layers, and adsorption I: some historical scientific context
Surfaces, double layers, and adsorption II: the interaction of H2O with mineral surfaces
Surfaces, double layers, and adsorption III: variation with pH
Surfaces, double layers, and adsorption IV: a diffuse layer in the Gouy-Chapman model
Surfaces, double layers, and adsorption V: a compact layer in the Stern model
Surfaces, double layers, and adsorption VI: models of specific or "Type II" adsorption
Surfaces, double layers, and adsorption VII: different surfaces in one crystal
Adsorption of cations, and adsorption isotherms
Trends in the adsorption of cations on mineral surfaces
An explanation of "point of zero charge" - Part I
An explanation of "point of zero charge" - Part II
Adsorption of hydrated Mg2+ on calcite as an inhibitor of calcite growth
Incorporation of trace elements
Distribution coefficients and the co-precipitation of trace and minor elements
An explanation of why distribution coefficients vary with precipitation rate and temperature
Precipitation of trace elements from an evolving fluid
The solubility of minerals
Solubility of minerals I: solubility products (Ksp values)
Comparative solubility of minerals I: fluorides, oxides, nitrates, and sulfates
Comparative solubility of minerals II: Explanations via ionic strength and cation-cation repulsions
Comparative solubility of minerals III: Explanations via bond strength and cation-cation repulsions
Comparative solubility of minerals IV: It's not about z/CN bond strength
Basics of Mineralogy
The meaning of "mineral"
The definition of "mineral", Part I: The 1800s (and their influence today)
The definition of "mineral", Part II: The 1900s
The definition of "mineral", Part III: The 2000s, and a modern definition
The diverse meanings of "mineralize"
Compendia of minerals
Minerals as the most fundamental level of observation in the Earth Sciences
Crystallinity, coordination, and chemistry
Crystallinity and mineral stability I
Crystallinity and mineral stability II
The ubiquity of crystallinity
Coordination of anions around cations
Two-fold and three-fold coordination
Four-fold (tetrahedral) coordination
Six-fold (octohedral) coordination
Eight-fold (cubic) coordination
Twelve-fold coordination
Coordination and radius ratios
Variation in C-O and Si-O coordination
Chemical Bonding
Chemical Bonding II: sketches
Mineralogical implications of the hardness and softness of ions
Repulsion between cations, and mineral stability
Linkage of polyhedra in minerals
Systematic Mineralogy
-ides and -ates in mineralogy
A table of systematic mineralogy I: basic categories
A table of systematic mineralogy II: redox implications
A table of systematic mineralogy III: redox pairs
A table of systematic mineralogy IV: numbers of minerals
Notes to accompany "A table of systematic mineralogy"
A table of hybrid minerals
Radical groups in minerals, and the oxysalts,
sulfosalts, seleniosalts, tellurisalts, and fluosalts
Patterns in the compositions of minerals I: carbonates and sulfates
Patterns in the compositions of minerals II: silicates and phosphates
Patterns in the compositions of minerals III: the oxysalt or "ate" minerals
Patterns in the compositions of minerals IV: chlorides and oxides
Patterns in the compositions of minerals V: the "ide" minerals
Patterns in the compositions of minerals VI: a summary
Mineral Groups
Silicate minerals
Silicon in aqueous solution
The many forms of silica (SiO2) I: minerals and solutes
The many forms of silica (SiO2) II: rocks and other aggregates
Feldspars and feldspathoids I: tetrahedral substitutions
Feldspars and feldspathoids II: the common feldspars
Feldspars and feldspathoids III: the feldspars of large cations
Feldspars and feldspathoids IV: the boron-bearing feldspars
Feldspars and feldspathoids V: a summary of the feldspars
Feldspars and feldspathoids VI: feldspar polymorphism and solid soutions
Feldspars and feldspathoids VII: the feldspathoids
Feldspars and feldspathoids VIII: the limits of interstitial cations
Bowen's Reaction Series and Igneous Rocks
Bowen's Reaction Series I: The original document
Bowen's Reaction Series II: A silicon-centered explanation
Bowen's Reaction Series III: Melting temperatures of oxides
Bowen's Reaction Series IV: Toward a broader explanation
Bowen's Reaction Series V: A summary explanation
Generalized trends in silicate minerals in igneous rocks
Rate of cooling of magmas and the texture of igneous rocks
Origins of melts and magmas I
Origins of melts and magmas II
Clay minerals
Clay Mineralogy I: Phyllosilicate Minerals
Clay Mineralogy II: T-O-T phyllosilicate Minerals
Clay Mineralogy III: Compositions of T-O-T phyllosilicate minerals
Why clay (Al-phyllosilicates) is clay (fine-grained minerals)
X-ray diffraction and the powder method
Carbonate minerals
Cation sites in the common carbonate minerals
CaCO3 minerals
Stability and solubility of carbonate minerals of divalent cations
Factors favoring precipitation of CaCO3 as calcite or as aragonite
Adsorption of hydrated Mg2+ on calcite as an inhibitor of calcite growth
Mg-bearing carbonate minerals
Solubility of common carbonate minerals
Occurrence of common carbonate minerals
X-ray diffraction (XRD) of aragonite and calcite
The diversity of carbonate minerals
The many wonders of CaCO3
Non-silicate minerals relevant to historical geology
Properties of Minerals
Properties of minerals
Density of minerals
Density of Minerals I: Inter-radical cations
Density of Minerals II: Complex anions in oxysalts
Density of Minerals III: Oxides and stoichiometry
Density of Minerals IV: Simple anions
Density of Minerals V: Coordination
Density of Minerals VI: The effect of structural H2O
Density of Minerals VII: The effect of OH- in oxysalts
Density of Minerals VIII: The significance of crystal structure
Hardness of minerals
Hardness of Minerals I: the Mohs Scale
Hardness of Minerals II: Variation with structure and bonding
Hardness of Minerals III: hydrous vs. anhydrous minerals
Hardness of Minerals IVa: variation with bond length and cation size
Hardness of Minerals IVb: variation with bond length and anion size
Hardness of Minerals Va: Variation among oxides and oxysalts
Hardness of Minerals Vb: Variation among oxides and oxysalts
Hardness of Minerals VI: Effect of crystal face and direction
Density and hardness of minerals
Density and hardness I: a first look
Density and hardness II: a look using normalized density
Density and hardness III: Knoop hardness and normalized density
Melting temperature and hardness of minerals
Melting temperature and hardness of minerals
Compressibilty of minerals
Compressibility of minerals as a function of cation and anion size
Color of minerals
Color of minerals
Color in the olivine-group minerals
Color in carbonate minerals
Topics in Geochemistry
Isotopic geochemistry
Isotopes (with examples from carbon to chlorine)
Isotopes (with examples from lead to uranium)
Isotopes - the basics, and why we care
Relative abundance of stable isotopes: even-odd relationships
Commonly used stable isotopes
The delta symbol in stable isotope geochemistry
Isotope notations: %s, δ values, and ε values
A simple mass spectrometer
Isotopic mixing curves
Fractionation of carbon isotopes in photosynthesis
Fractionation of oxygen isotopes in formation of minerals from solution
An explanation of why isotopic fractionation varies with precipitation rate and temperature
Oxgyen isotope composition of calcite as a function of temperature and water composition
A graphic explanation of fractionation of oxygen isotopes between water and calcite
Oxygen isotope fractionation in the precipitation of calcite and aragonite
Isotopologues of CaCO3 applied to past temperature
The "clumped isotope" paleotemperature method for carbonates
Rock-water ratios and the stability of δ13C and δ18O values in carbonate materials
C and O stable isotope compositions of Cenozoic Earth-surface materials of all sorts, Part I
C and O stable isotope compositions of Cenozoic Earth-surface materials of all sorts, Part II
The δ13C record of marine limestones
The δ18O record of marine limestones
Correlation of charge and δ13C in Earth-surface C-bearing materials
Parallels in fractionation of isotopes and partitioning of trace elements
Fractionation of oxygen isotopes in formation of glacial ice
Half-lives and abundances of radioactive isotopes
Half-lives of radioactive atoms and measurement of age
Decay systems commonly used in radiometric dating
Terrestrial carbonates
Earth's naturally occurring carbonate materials
Degassing of CO2 in caves and precipitation of speleothems
Controls on the δ13C and δ18O of spelean CaCO3
C and O stable isotope compositions of speleothems
Sources of C and O in the CaCO3 of speleothems, or,
Why δ13C varies more than δ18O in speleothems
Isotopic evolution of cave waters with degassing of CO2 and evaporation
C and O stable isotope compositions of pedogenic carbonates
δ13C and δ18O profiles in pedogenic carbonates
Pedogenic CaCO3 (caliche) as a record of ancient atmospheric concentration of CO2
Organic geochemistry
Organic and inorganic compounds
Organic and inorganic compounds, and biogenic and non-biogenic materials
Unpaired electrons of atoms and the compositions of simple molecular substances
Organic structures and functional groups relevant to geochemistry and environmental chemistry
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C-H-O chemistry of some naturally occurring organic substances
C-H-O chemistry of some naturally occurring redox reactions
Atmospheric geochemistry
Why the gases of the atmosphere are gases
The chemical composition of Earth's atmosphere I
The chemical composition of Earth's atmosphere II: the big two
The chemical composition of Earth's atmosphere III: the noble gases
The chemical composition of Earth's atmosphere IV: water vapor
The chemical composition of Earth's atmosphere V: the major carbon-bearing species
The chemical composition of Earth's atmosphere VI: anthropogenic inputs
The multiple forms of oxygen
The chemical composition of Earth's atmosphere VII: the O-bearing radicals
The chemical composition of Earth's atmosphere VIII: the role of the OH radical
The chemical composition of Earth's atmosphere IX: residence times
Acid Rain I: the big picture
Acid Rain II: the details
The Suess Effect
Geochemistry of some natural waters
The typical solutes of geochemical solutions (i.e., of natural waters)
Chemistry of some river waters with respect to bedrock lithology
Variation in groundwater chemistry with host lithology
Variation in groundwater pH and total dissolved solids with depth
Change in pH and total dissolved solids of groundwater with depth and time
Variation in concentration of dissolved silica with depth
Variation in dissolved O2 with depth in groundwater
Chemistry of lacustrine waters
Size and salinity of lakes, and the ocean(s) I
Size and salinity of lakes, and the ocean(s) II
Relationships of lakes and the ocean to their drainage basins: a plot of hydrologic dominance I
Relationships of lakes and the ocean to their drainage basins: a plot of hydrologic dominance II
Overturn of freshwater lakes
Weathering, soils, and soil development
Carbon dioxide in soil
Typical reactions in the chemical weathering of silicate rocks
Weathering, alkalinity, and acidity across the periodic table
Goldich's Weathering Series explained in terms of bond strength
Mineralogy of soils from the Piedmont and Blue Ridge of the southeastern United States
Soil development through time I
Soil development through time II
The complementary nature of near-surface waters and minerals
Environmental issues
DDT, Part I: chemical and ecological aspects
DDT, Part II: Silent Spring and the banning of agricultural use of DDT
Chlorofluorocarbons (CFCs) and related compounds: a gallery
CFCs and related compounds, and their environmental history
Chlorofluorocarbons (CFCs) and related compounds: a tabular summary
Chlorofluorocarbons (CFCs) and related compounds: atmospheric concentrations through time
Simple CFCs in the spectrum from carbon tetrachloride to carbon tetrafluoride
Toxicology and past use of Pb (lead)
Greenland ice records of lead transport in the atmosphere
Acid mine drainage I: chemical reactions for oxidation of sulfides
Acid mine drainage II: patterns in acid mine drainage
Geochemistry of deep-basin brines
Deep-basin brines I: Density, TDS, and chloride
Deep-basin brines II: Variation in major cations
Deep-basin brines III: Dominance of Ca2+ among cations
Deep-basin brines IV: Dominance of Cl- among anions
Deep-basin brines V: Effect of Ca2+'s dominance on pH and SO42- concentration
Deep-basin brines VI: Comparison with shallower groundwater
The Oceans
The Geography and Geology of the Oceans
Straits I: width and depth
Straits II: connections of the major ocean basins
Straits III: closure of the largest gulfs, bays, and marginal seas
What is an ocean, and how many does Earth have?
Plate tectonics: divergent, convergent, and transform boundaries
Mid-ocean ridges
A mid-ocean ridge vent or "black smoker", Part I
A mid-ocean ridge vent or "black smoker", Part II
Photosynthetic and chemosynthetic marine ecosystems: the sea surface, hydrothermal vents, and cold seeps
A cross-section through the North Atlantic to scale: no vertical exaggeration
Possible causes of sea-level change
Ocean Circulation
Global climate zones: a seven-page work-up
Global climate zones: one detailed page from the above
Variation of atmospheric pressure between and within climatic belts
The Trade Winds and Westerlies wind belts
Surface circulation: the ocean currents:
Gyres of currents: building a gyre
Some origins of eddies in the (northern hemisphere) oceans
Cold-core rings and warm-core rings
Gyres of currents, and eddies
Gyres of currents, idealized and eddified
ENSO (El Niño) events
The Ekman spiral, dynamic topography, and coastal and equatorial upwelling
The Ekman spiral, dynamic topography, and geostrophic currents
Interactions of currents, tides, and waves
Interactions of currents, tides, and waves II
Deep circulation:
The thermocline
The thermocline and deep circulation of the Atlantic - schematic
The thermocline and deep circulation of the Atlantic - less schematic
Density of seawater at the sea surface
Why density of seawater increases with salinity
Expressions for the deep circulation of the oceans
Two models of deep ocean circulation
Models of deep ocean circulation in the 2010s
The Warm Saline Deep Water hypothesis
Chemistry of seawater / marine chemistry / chemical oceanography
The twenty-four most abundant solutes in seawater
Marine nutrient cycles I: Nitrogen
Marine nutrient cycles II: Phosphorous
Marine nutrient cycles III: Silicon
Marine nutrient cycles IV: Iron
Iron as a limiting nutrient in the ocean
Variation in concentration of solutes in the oceans I: Nutrients (nitrate, phosphate, silica)
Variation in concentration of solutes in the oceans Ia: Nutrients and biological productivity
Variation in concentration of solutes in the oceans II: Dissolved oxygen (O2)
Variation in concentration of solutes in the oceans III: Carbon dioxide (CO2)
Variation in concentration of solutes in the oceans IIIa: Carbon dioxide and the carbonate compensation depth (CCD)
Variation in concentration of solutes in the oceans IV: Oxidation of sinking organic particles - a summary
Variation in δ13C of dissolved inorganic carbon in the oceans
Variation in concentration of solutes in the oceans V: Scavenged ions
Variation in concentration of solutes in the oceans VI: The conservative solutes
Concentrations and residence times of solutes in seawater I: an oceanographic perspective
Concentrations and residence times of solutes in seawater II: a geochemical perspective
Concentrations and residence times of solutes in seawater III: a combined perspective
Box models of the long-term carbon cycle
Boron in marine calcite as an indicator of ancient PCO2
The Black Sea
The Black Sea I: Geography
The Black Sea II: A schematic cross-section
The Black Sea IIIa: Variation with depth
The Black Sea IIIb: Chemical variation with depth
The Cenozoic, Quaternary, Pleistocene, and Holocene
Isotopic records of the Cenozoic
From deep-sea sediments to paleoclimate records
Marine isotope stages and substages
Oxygen isotope records of Cenozoic global cooling and glaciation
Terminology and timing of some later Quaternary climatic events
Five million years of climate and hominin history
The Paleolithic in the context of oxygen isotope records of Cenozoic cooling and glaciation
The last 150,000 years of human and glacial history
The last glacial cycle in marine sediments, Greenland ice, and Antarctic Ice
Terminology and timing of some later Quaternary climatic events
Holocene ice core isotopic records, climatic events, and human history
Democracy in the context of human and glacial history
Northern Hemisphere climate over the last two thousand years
The Quaternary
Milankovitch cycles I: eccentricity of Earth's orbit, seasonality, and extent of glaciation
Milankovitch cycles II: tilt of Earth's axis, seasonality, and extent of glaciation
Milankovitch cycles III: precession of the seasons, seasonality, and extent of glaciation
Wisonsinan, Illinoian, and earlier glacial deposits of North America
AD, CE, BC, BP, calendar years, radiocarbon years, and all that
Calibration of radiocarbon dates
Calibration of radiocarbon dates II
Radiometric dating via U-series disequilibrium I
Radiometric dating via U-series disequilibrium II
Contextual Materials
Basic Geology
Meteorites, and their implications for the origin of Earth
A simple model of the evolution of the early Earth, Part I
A simple model of the evolution of the early Earth, Part II
A simple model of the evolution of the early Earth, Part III
A simple model of the evolution of the early Earth, Part IV
The age of the Earth and our solar system
The standard geologic time scale
Earth at a glance
Plate tectonics and Earth dynamics
Plate tectonics: divergent, convergent, and transform boundaries
Faults and folds, and how they form
Rocks, Part I
Rocks, Part II - the rock "cycle"
Rocks, Part III
Origins of melts and magmas I
Origins of melts and magmas II
Bodies of igneous rock
Metamorphism and metamorphic rocks
The origin of sedimentary rocks
The origin of siliciclastic and biochemical sedimentary rocks
Lithification of sediments to sedimentary rocks I: Proceses
Lithification of sediments to sedimentary rocks II: Possible pathways
Lithification of sediments to sedimentary rocks III: Compaction
Lithification of sediments to sedimentary rocks IV: Cementation
Steno's princples of sedimentary layers
Unconformities and their significance to geologic time
The idea of determining Earth's age from the thickness of accumulated sediments -
and why it fails
Relative dating: superposition, inclusions, and cross-cutting relationships
Movement of facies of sediment with rising sea level
Movement of sedimentary facies with change of sea level
Movement of sedimentary facies with change of sea level, and sequences
Three thoughts about fossils
The fun mysteries and important practicalities of geology and the geosciences
The Bigger Picture
Ways of understanding I
Ways of understanding II
The meaning of the word "Data" in science
Sources of geological information in the field
Large-scale flow in Earth Systems
Earth Dynamics: a unifying view of plate tectonics and mantle flow, meridional ocean circulation, and atmospheric circulation
A Phanerozoic paleoenvironmental timeline
The size of things
Human awareness of space and time
(a review of how science has changed human awareness of the world, best viewed in .ppt)
PPT file
