Cutting Edge > Petrology > Teaching Activities > Major Element Control Presentation

Major Element Control Presentation

Kurt Hollocher
,
Union College
Author Profile

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.


This page first made public: Jun 23, 2008

Summary

The presentation is an introduction to the control of magma chemical compositions by the fractionation of crystallizing phases. It is followed by a lab exercise where students interpret volcanic rock petrology and a geochemical data set (from Iceland) in terms of sequences of fractionating phases.

Used this activity? Share your experiences and modifications

Context

Audience

This presentation is designed for a sophomore or junior level petrology course for majors.

Skills and concepts that students must have mastered

How the activity is situated in the course

In context, this presentation is shown after phase diagram lectures and exercises, and it is linked to them by examining phase diagrams that illustrate the crystallization sequence (Olivine-plagioclase-augite). Further, a following lab exercise has the students deduce somewhat similar crystal fractionation controls for a set of Iceland lavas (for phenocryst petrology) and geochemical data sets (with which control lines are plotted).

Goals

Content/concepts goals for this activity

The presentation itself is not enough to make the connection between liquid composition changes, phase diagrams, and chemistry, but in the context of earlier phase diagrams, presentation, return to phase diagrams, and the petrology-geochemistry Iceland exercise, it helps get across the idea of how crystal fractionation can control magma evolution.

Higher order thinking skills goals for this activity

Other skills goals for this activity

Description of the activity/assignment

The presentation is an introduction to the control of magma chemical compositions by the fractionation of crystallizing phases. It is followed by a lab exercise where students interpret volcanic rock petrology and a geochemical data set (from Iceland) in terms of sequences of fractionating phases.

It is a useful as an introduction because it shows clearly, with data points, interpreted lines, and oral explanation how fractionating crystals can, in principal, control the chemical composition of derivative magmas.

In context, this presentation is shown after phase diagram lectures and exercises, and it is linked to them by examining phase diagrams that illustrate the crystallization sequence (Olivine-plagioclase-augite). Further, a following lab exercise has the students deduce somewhat similar crystal fractionation controls for a set of Iceland lavas (for phenocryst petrology) and geochemical data sets (with which control lines are plotted).

The presentation itself is not enough to make the connection between liquid composition changes, phase diagrams, and chemistry, but in the context of earlier phase diagrams, presentation, return to phase diagrams, and the petrology-geochemistry Iceland exercise, it helps get across the idea of how crystal fractionation can control magma evolution.

Determining whether students have met the goals

More information about assessment tools and techniques.

Download teaching materials and tips

Other Materials

Supporting references/URLs

See more Teaching Activities »