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Teaching Petrology in the 21st Century
Montana State University, Bozeman, MT
Cutting Edge > Petrology > Teaching Activities > Graphing Chemical Data to Identify Fractional Crystallization

Graphing Chemical Data to Identify Fractional Crystallization

John Brady
,
Smith College
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Summary

Students are given major-element, whole-rock chemical analyses from ten samples of lava from the 1868 eruption of Mauna Loa. They do not know sequence of eruption, only that the lavas came from the same volcano. Students are asked to evaluate the hypothesis that the observed chemical variation is due to the fractional crystallization of olivine. The hypothesis can be tested any of a number of graphs. Several examples are given in the accompanying Excel workbook.

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Context

Audience

This activity is designed for a required course in petrology for majors (sophomore or junior level).

Skills and concepts that students must have mastered

Students should be familiar with basic igneous processes.

How the activity is situated in the course

This is a stand-alone exercise.

Goals

Content/concepts goals for this activity

Students are asked to evaluate the hypothesis that the observed chemical variation in lava is due to the fractional crystallization of olivine. The hypothesis can be tested any of a number of graphs (provided).

Higher order thinking skills goals for this activity

This activity involves data analysis.

Other skills goals for this activity

Description of the activity/assignment

Students are given major-element, whole-rock chemical analyses from ten samples of lava from the 1868 eruption of Mauna Loa. They do not know sequence of eruption, only that the lavas came from the same volcano. Students are asked to evaluate the hypothesis that the observed chemical variation is due to the fractional crystallization of olivine. The hypothesis can be tested any of a number of graphs. Several examples are given in the accompanying Excel workbook.

Determining whether students have met the goals

More information about assessment tools and techniques.

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