Modern Analytical Methods in
Radiogenic Isotope Geochemistry:
A Semester Long Applied Course
Jeff Vervoort
Washington State University
Motivation:
Finding a mechanism to train a group of students
to use the laboratory safely and intelligently
…so that the students:
Understand what they are doing.
Gain the skills and knowledge so that they can do further
independent geochemical work (e.g., thesis research, etc.)
Context
Audience: This course is designed for beginning graduate
students and advanced undergraduates. The pre-requisites
for the course are Introductory Geochemistry and (ideally)
radiogenic isotope geochemistry.
Skills and concepts that students must have mastered: A
basic understanding of chemistry and geochemistry is
required. An understanding of the principles of radiogenic
isotope geochemistry would be advantageous.
Structure of the Course
Structure: This is a laboratory based course with lectures
scheduled to provide background for the laboratory work.
By necessity, the course is front-end loaded, with heavy
scheduling of lecture and lab sessions at the beginning and
a much lighter (scheduled) load at the end of the semester
(but replaced with independent project).
Goals:
Understand the principles behind different geochemical
methods (e.g., sample preparation; solution chemistry;
mass spectrometry).
Know the quality of the data (precision, accuracy). This is
important for the correct interpretation of the data (not all
data are created equal).
Gain the skills and knowledge so that the students can do
further independent geochemical work (e.g., thesis
research, etc.).
Think critically (question everything!).
Course Structure:
Laboratory
& Lecture
Laboratory work drives the lectures
Projects:
Group Project:
Class works on one project collectively
(e.g., Rb-Sr and Sm-Nd isotope geochemistry)
Individual Project:
Students work on independent projects of
their choosing
Lecture
Introduction to the elements
Geochemical behavior of the elements
Sample preparation
Ion chromatography
Rb-Sr and Sm-Nd chromatography
Use of isotopic tracers; principles of isotope dilution
Determination of analytical blanks
Fundamentals of mass spectrometry
TIMS; MC-ICPMS;mass bias; interference corrections
Data reduction
Assessment of data (Precision, accuracy, quality)
Interpretation of data
Presentation of results (e.g., epsilon values etc.)
Laboratory
Introduction to the laboratory (including safety training)
Fundamental laboratory techniques (mixing acids, pipetting)
Titration of acids
Cleaning protocol
Sample dissolution and treatment
Ion chromatography
e.g., Rb-Sr, Sm-Nd, Lu-Hf, Pb, etc.
Collection of blanks
Preparation of samples for mass spectrometry
Mass spectrometry
standards; unknowns; blanks
Data reduction (mass bias & interference corrections, etc.)
…all lab and lecture topics are presented in the context
of the group class projects
Group Project:
Class works on one project collectively
(e.g., Rb-Sr and Sm-Nd isotope geochemistry)
…end product:
Submit short report on results (reduce,
present, and interpret isotope data)
Laboratory
Introduction to the laboratory (including safety training)
Fundamental laboratory techniques (mixing acids, pipetting)
Titration of acids
Cleaning protocol
Sample dissolution and treatment
Ion chromatography
e.g., Rb-Sr, Sm-Nd, Lu-Hf, Pb, etc.
Collection of blanks
Preparation of samples for mass spectrometry
Mass spectrometry
standards; unknowns; blanks
Data reduction (mass bias & interference corrections, etc.)
Lecture
Introduction to the elements
Geochemical behavior of the elements
Sample preparation
Ion chromatography
Rb-Sr and Sm-Nd chromatography
Use of isotopic tracers; principles of isotope dilution
Determination of analytical blanks
Fundamentals of mass spectrometry
TIMS; MC-ICPMS;mass bias; interference corrections
Data reduction
Assessment of data (Precision, accuracy, quality)
Interpretation of data
Presentation of results (e.g., epsilon values etc.)
Independent Project
Proposal
Students submit a proposal for their project
Research Plan
Details of the analytical methods
Analytical work
Students in charge of their own schedule
End Products
Written: Detailed methods section
Oral: Presentation of research and results
What has worked (students):
*This IS problem based learning
*Students have learned to think critically
*Hands-on techniques are an effective way to teach
geochemical fundamentals (relevance)
*Many unexpected (and very intriguing) results
*Results have led to further work and impressive end
products (presentations at meetings; providing the basis for
thesis work and further research)
Independent Projects
Examples:
Sr-Nd isotopes in the Talkeetna Arc
Hf-Nd isotopes in the Aleutian Arc
Sr-Nd-Pb-Hf isotopes in mantle xenoliths
Sr-Nd-Pb isotopes of Canary island volcanics
HFSE chemical separation protocol
Ca isotope chemistry and analysis
Sr isotopes in stream and soil water
Sr isotopes in paleosols
LA-ICPMS zircon dating of lower crustal
xenoliths
What has worked (Instructor):
*Moves the instructor in new and unexpected directions
(letting the genie out of the bottle)
*Find out interesting things along the way (serendipity)
*Can be used to set up new techniques in the lab
What has not worked:
*Diverse interests in this course
…students want different aspects from this course
…hard to focus on the scientific literature in depth
*Only works (in my class) with small numbers.
*Very time consuming.
Challenges/Problems:
*Diverse interests in this course
…students want different aspects from this course
…hard to focus on the scientific literature in depth
*Time consuming
*This kind of course can only accommodate a few students
*Scheduling (irregular hours; irregular times throughout the
semester)
*Need to start with a common (group) project so that
students can help each other (avoids chaos)
*Project results may not be interesting
Applicability:
*This course grew out of my needs at WSU, but has
applicability to other departments and situations
--applicable to other analytical techniques
--senior thesis work
--promoting undergraduate research
An Introduction to
Calcium Isotopes
Methods and Madness
Amy Carey
Geol 597
U-Pb Geochronology of Snake
River Plain Xenoliths
Dave Wolf
Geology 597
Spring, 2005