Calculating Rb-Sr Isochrons

Andy Barth

Indiana University~Purdue University, Indianapolis

This activity is part of the On the Cutting Edge Peer Reviewed Teaching Activities collection. (view details)

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Scientific Accuracy
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Initial Publication Date: October 22, 2008 | Reviewed: October 21, 2012 (see revision history: 2 events)

Summary

Radioisotopes, Geochemical Analysis, Geochemistry, Igneous Rocks | College Lower (13-14), College Upper (15-16), Graduate/Professional

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Context

Audience

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

Skills and concepts that students must have mastered

How the activity is situated in the course

This is a stand-alone exercise.

Goals

Content/concepts goals for this activity

This activity is designed to help students understand how to calculate Rb-Sr isochrons and addresses isotope heterogeneity and sampling at various scales.

Higher order thinking skills goals for this activity

Other skills goals for this activity

Description of the activity/assignment

This is a spreadsheet that I use in petrology to walk students through calculating Rb-Sr isochrons and talking about isotope heterogeneity and sampling at various scales. The example exercise is the Tuolumne intrusive series. The file, available for download below, contains workbooks (see different tabs) with example isochrons and a spreadsheet of data for the homework problems.

Determining whether students have met the goals

Students have successfully met the goals of this exercise if they answer the homework problem set completely and accurately.

More information about assessment tools and techniques.

Teaching materials and tips

Teaching Notes to Accompany Calculating Rb-Sr Isochrons (Microsoft Word 75kB Oct21 08) -- directions on how to calculate slopes and intercepts from the Excel spreadsheet, and how to use the slope to calculate an age.

Rb-Sr Isochron Examples and Homework (Excel 52kB Sep7 08) - this file contains examples and homework data for the exercise. Each example and homework data set is a separate tab in this Excel spreadsheet.