Fault rocks lab

John Singleton, George Mason University

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Summary

This lab is intended to give students some hands on experience looking at fault rocks with a suite of cataclasites and mylonites I have collected. The focus is on identifying key textural features in both hand sample and thin section and understanding how deformation within a fault zone varies with depth.

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Context

Audience

The target audience are students in a required undergraduate course in structural geology, but the lab could be modified for graduate level advanced structural geology course.

Skills and concepts that students must have mastered

This lab should follow lectures on brittle faults and ductile shear zones. Students should have previously completed a course in mineralogy (and ideally igneous and metamorphic petrology). One of the question requires a stereonet.

How the activity is situated in the course

This lab is a stand-alone exercise that builds on lecture material.

Goals

Content/concepts goals for this activity

It is important for students to relate lecture material to actual rocks. This lab gives students hands-on practice in: how to identify and classify brittle and ductile fault rocks, identification of mylonitic fabrics, determining deformation/recrystallization mechanisms in mylonites, and understanding how fault rocks and deformation mechanisms vary with depth.

Higher order thinking skills goals for this activity

The skill goals for this lab are: a) for students to make careful observation of rocks with the naked eye, hand lense, and microscope, and b) to make interpretations based on their observations.

Other skills goals for this activity

For some students this lab may be a good refresher in how to use a petrographic microscope.

Description and Teaching Materials

Fault rocks lab (Microsoft Word 2007 (.docx) 870kB May4 12)



Teaching Notes and Tips

Assessment

This lab will be successful if, after completing the lab, students feel comfortable identifying and classifying brittle and ductile fault rocks and identifying the key textural features in cataclasites and mylonites. Student's answers to the lab questions should be a good indicator of whether this in the case.

References and Resources