Using Data to Teach Igneous Petrology

submitted by

Pranoti M. Asher Georgia Southern University
Author Profile

This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

In order to make connections between the two disparate segments (lecture and laboratory) of a Petrology course; short exercises using real data accompany each laboratory exercise. Three examples are discussed pertain to granites, basalts, and andesites.
GSA Poster (Acrobat (PDF) 9.3MB Oct24 03)

Learning Goals

Content/Concepts:

Higher Order Thinking Skills:

Drawing conclusions from data
Making connections between data set and physical models

Other Skills:

Collecting data
Writing
Data analysis - using Excel, graphing software
Working with peers

Context

Instructional Level:

Undergraduate major

Skills Needed:

Enrolled in Petrology course
Microscope skills
Basic Geochemistry

Role of Activity in a Course:

The activities described in this poster make up a central theme in my Petrology course. All laboratory exercises are connected to topics covered in lecture.

Data, Tools and Logistics

Required Tools:

No special tools or equipment requried.
Excel required
Standard petrographic microscopes required.

Logistical Challenges:

Assist students with determining field of view using the various objectives on the microscope.

Evaluation

Evaluation Goals:

Assigning such activities allows students to retain materials learnt in lecture, have a better understanding of the lecture material, improve their ability to think critically, and gain experience in non-discipline skills such as writing, graphing, and working with peers.

Evaluation Techniques:

I have assessed the success of these exercises by using the traditional end of the semester evaluation forms - mostly anecdotal comments regarding the success of the laboratory portion of the course, how it fits with the lecture material

Description

At Georgia Southern University, Petrology is taught as a lecture course along with the accompanying laboratory. In order to make connections between the two disparate segments of this course; short exercises using real data accompany each laboratory exercise. Two examples are discussed below.

The first example is associated with a laboratory exercise on "Basalts, Andesites, Rhyolites and Tuff." In this laboratory, students examine and describe each of the rocks using hand specimens and thin sections. Once the rock descriptions are complete, the students evaluate the similarities and differences between these rocks (e.g., all the samples are porphyritic and contain plagioclase, anorthite content of plagioclase varies with composition). Students then work in small groups to calculate magma ascent rates from amphibole reaction rim thickness according to methods described by Farver and Brabender (2001). The students collect, appraise, and interpret their own data in the context of a much larger data set and model developed by Rutherford and Hill (1993). This addition to the exercise allows students to make linkages with lecture discussions on magma ascent rates and how they may be determined for recent volcanic eruptions.

The second example relates to a laboratory exercise on "Basalts." Here, students examine and report descriptions on hand-samples and thin sections of three different basalts: an olivine tholeiite from Kilauea, an alkali basalt from the Gregory rift in Kenya, and a Mesozoic diabase (quartz-normative tholeiite) from New England. Whole rock and trace element data for these samples are also provided. Students use their rock descriptions and the geochemical data provided to answer questions regarding the degree of saturation of the magma, classification of the type of basalt (requiring normative calculations), and the tectonic setting of each rock (analyzing trace element data). This part of the exercise reinforces lecture materials on phase diagrams and geochemical tools used to decipher tectonic origin of rocks.

Assigning such activities allows students to retain materials learnt in lecture, have a better understanding of the lecture material, improve their ability to think critically, and gain experience in non-discipline skills such as writing, graphing, and working with peers.