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.

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

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This page first made public: Oct 22, 2008

Summary

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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.

Download 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.
Cathedral Peak Granodiorite Graph (PowerPoint 2007 (.pptx) 39kB Sep29 09) - graph of problem solution. As an alternative to SLOPE and INTERCEPT, the student can get this information by making a scatter chart of the data, and then inserting a linear trendline with equation displayed on the chart....this is pretty visual and helpful for many students.

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