GEOL 8150: Earth-Surface Geochemistry

at the University of Georgia

GEOL 8150 is a geochemistry course taught by Bruce Railsback at the University of Georgia. It's offered every other year. The course has been taught eight times, in 1993, 1995, 1996, 1998, 1999, 2001, 2003, 2004, and 2006. It will presumably be offered in 2007, 2008, or 2009.

About GEOL 8150

Course Goals and Philosophy:
The goals of this course are (1) to enhance the application of chemical principles to geology by geology students who have had something like two semesters of undergraduate chemistry and perhaps a standard geochemistry course, and (2) to develop professional skills in synthesis of data, scientific writing, and public presentation. Goal 1 is to be achieved through lectures, problem sets, and an exam; Goal 2 is to be achieved through a project.

Class Format:
Students are given a packet of lecture notes (See Table of Contents below). To speed up the conveyance of information, to allow more interaction, and to avoid boredom, we don't have actual lectures. Instead, students read the lecture notes on a given topic and other reading on that topic before they are to be discussed. Then we meet to discuss the lecture notes and assigned readings. Our discussions center on student questions, which can range from background questions to questions about details to questions that expand on the material to questions about the whole lecture. Sessions at which there are no questions or discussion feature a quiz over the lecture notes and readings. In 2006, the lecture notes were 312 pages.

Exams:
The exams will consist of essay questions that will be distributed prior to the exams. The final exam will include questions over student presentations. The only numbers that students are explicitly asked to reproduce are the solubility of quartz (in ppm SiO2(aq)) and the solubility product of calcite.

Paper/Presentation Project:
Each student is to write a paper and give a classroom presentation on a topic of his or her choice. These projects will involve detailed examination of the literature on the topic chosen and synthesis of what is known. The research should focus on a question like "what can or does geochemistry (or an area of geochemistry) tell us about Topic X?", where Topic X is a geological process, event, or phenomenon. It is assumed that students will choose topics relevant to their thesis research or topics of great interest to them. Completion of the project should leave the student with a solid state-of-the-art knowledge of what is known, what has been done, and what needs to be done in a given area of study.

Table of Contents for GEOL 8150 Lecture Notes

Prologue

Part I: Principles

I. "Solutions": some ugly realities
A. Definitions
B. Increasing complexity of solutions
C. Speciation in the (geochemically) real world

II. Free energy, K's, solubilities and activities
A. Activities of solutes
B. Activity of water
C. Saturation State
D. Free energies, equilibrium constants, and solubilities
E. Effect of Temperature

III. Solutions and Solids I ("Colloid Chemistry")
A. Surface Effects on Solids and Double Layers
B. Adsorption and the Solution

IV. Solutions and Solids II
A. Crystallization
B. Dissolution
C. Transport of Dissolved Solids
D. Examples of Kinetic Studies
E. Solid-liquid-solid interactions I: Ostwald's step rule and Recrystallization
F. Solid-liquid-solid interactions II: Solubility, Particle Size, and Ostwald Ripening

V. Stable Isotopes
A. Definitions and standards
B. Fractionation - separation of isotopes
C. Equilibrium Fractionation of isotopes in crystallization
D. Some Kinetic Fractionations
E. Strontium Isotopes
F. Sm and Nd

VI. Rare Earth Elements
A. Definitions and Representations

Part II: MATERIALS

VII. Silica
A. Forms of silica
B. Solubility Behavior
C. The Fate of Biogenic Silica

VIII. CO2, HCO3-, and CO32-, and CO3-bearing Minerals
A. Carbonate equilibria - Version 1
B. Carbonate equilibria - Version 2
C. Alkalinity
D. CaCO3

IX. Clay Minerals
A. Clay Mineralogy
B. Cation Exchange and Clay Minerals

X. Water
A. Description/characterizarion of Natural Solutions
B. Graphic Representation of Water Chemistry Data
C. Characterizing the quality of chemical analyses
D. A caveat about trace element concentrations

Part III: Earth-Surface Systems

XI. Rain Water
A. Major Element Chemistry
B. Acidity of Rain Water
C. Trace Elements in Rain Water

XII. Weathering (and Soils)
A. CO2 from Plants
B. Minerals for Weathering

XIII. Soils (and Weathering)
A. Variation with Climate and Lithology
B. Variation with Depth
C. Variation on Soils through Time: Soil Development
D. Cations in Smectites
E. Rare-Earth Elements in Soils
F. Organics in soil (and groundwater)

XIV. Groundwater
A. Variation in pH
B. Variation in TDS
C. Variation in Dissolved Silica
D. Variation in Groundwater Chemistry with Lithology
E. Equilibration with Minerals
F. Oxidation & Reduction Reactions
G. Experimental Studies of Rock Weathering and Groundwater

H. Rain water, weathering, soils, and groundwater: a summary

XV. River Water and Estuaries
A. River Water
B. Trace Elements
C. Acidity
D. Acid Mine Drainage
E. Estuaries

XVI. Lakes
A. Limnology and eutrophy
B. Major-element chemsitry of lakes
C. Acidification of lakes

XVII. The Oceans
A. Ocean Circulation
B. Chemical Composition of seawater
C. Subdivision of elements/constituents in the oceans
D. Some effects of, or related to, varying oxygenation of the oceans
E. Box models and budgets of oceans
F. Silica Fluxes and the Silica Cycle

XVIII. The History of the Atmosphere and Oceans
A. O2, CO2, and the C and S Isotopic Records
B. Seawater Chemistry and the Evaporite Record
C. The Isotopic Record of Cretaceous to Modern Oceans
D. The O Isotope Record
E. Other Isotopic Records of the Oceans
F. Closing Caveat

XIX. Clay/Shale Diagenesis
A. Illitization of Smectite
B. Destruction of Kaolinite

XX. Deep Groundwaters / Deep-Basin Brines
A. Terminology
B. Why Care about Deep-Basin Brines?
C. Some Possible Processes Generating Subsurface Brines
D. Geochemistry of some deep basin brines
E. Oxygen Isotopes
F. Organic acid anions
G. Possible sources of water for brines

XXI. The Water and Rock Cycles

Some diagrams generated for or around the course:

A figure showing the size of objects from protons to the Earth, with its implications for the smallest organisms and mineral particles.
A figure showing Organic Structures and Functional Groups Relevant to Geochemistry and Environmental Chemistry.
A plot of the Abundances and half-lives of C, N, O, and S isotopes.
A plot of Ionic charge and radius from C^4- to Mn⁷⁺.
A figure comparing nucleation and crystal growth on an existing lattice.
A figure explaining why very small particles have greater solubility than large particles.
An explanation of Why clay is clay (why clay minerals are clay-sized).
A graphic explanation of Fick's First and Second Laws of diffusion (for the calculus-impaired).
An illustration of carbonate speciation (CO₂, H₂CO₃, HCO₃^-, and CO₃^2-).
Two triangular diagrams showing the compositions of various clays (smectites, illite, etc).
(with major acknowledgements to Steve Altaner)
A chart of the geochemical redox conditions of some important elements.
Of Ions and Orbitals - a large pdf diagram pondering coordination and structure of molecules and crystals.
A periodic table designed specifically for this course.

Geochemical Links

Cornell University's extensive Geochemical Links.
Illinois State Academy of Sciences's Geochemistry Links.
The Stanford University Library's list of geochemical resources.
Jerzy Weber's lists of links on the chemistry and other aspects of soils.

Links for Chemists.
The history of Chemistry, including Wilhelm Ostwald (one the course's major figures).

USGS Geochemical Software.
Chemfinder page for identification of chemical compounds.
The Chemist's Art Gallery of chemical animations and visualizations.
Virginia Tech's list of Acronyms of Analytical Instrumentation and Techniques.
Chemical Dictionaries.

The Geochemical Society.
International Association of Geochemistry and Cosmochemistry.
American Chemical Society Geochemical Division.

A scenic but disgusting little bit of geochemistry.

To Railsback's main page
To the UGA Geology Home Page
email to Railsback at rlsbk@gly.uga.edu