Teaching notes


Audience: undergraduate- or graduate-level petrology course.

Skills and concepts that students must have mastered: Basic knowledge of plate tectonic settings and processes of igneous differentiation is assumed for this exercise. The students should be familar with the theory and practice of variation diagrams and normalized REE plots, and should know how to manipulate and plot data in Excel spreadsheets.

How the activity is situated in the course: This activity could be used fairly early in an igneous petrology course to introduce the importance of plate tectonics in generating igneous rock diversity. It is recommended that this activity follow material on igneous processes, such as fractional crystallization and magma mixing.


Content/concepts goals for this activity: Students who complete this exercise should be able to:
  1. use the GEOROC online geochemical database to extract useful whole-rock major- and trace-element data
  2. make useful geochemical plots (variation and normalized REE diagrams)
  3. interpret geochemical plots to suggest or rule out possible petrogenetic processes

Higher order thinking skills goals for this activity: This exercise requires students to formulate hypothesis based on geochemical data, and to compare/contrast datasets.

Other skills/goals for this activity: Students gain practice in using an Excel program to plot geochemical data, interpreting geochemical plots, working in groups, and making presentations in class. In addition, the act of obtaining and using data from online databases like GEOROC informs the students about the powerful resources that have recently become available to the scientific community via the creation of digital cyberinformatics and cyberinfrastructure. A carefully guided approach of guiding students into these databases, through the various steps required to screen, download, import, and use their data, empowers the students in a tangible, practical way to think and act like scientists.


This is up to the instructor.