Teach the Earth > Sedimentary Geology > Teaching Activities > Tutorial Petrographic Image Atlas for Carbonates

Tutorial Petrographic Image Atlas for Carbonates

Kitty Milliken
University of Texas at Austin
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This product is a highly interactive collection of annotated digital images.

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See the Sandstone Tutorial to get information on historical context, the general character of the atlases, suggestions for instructors, and references.

Skills and concepts that students must have mastered

Ideally, introductory courses, mineralogy, and crystallography.

How the activity is situated in the course

A laboratory supplement to be used mostly outside of organized laboratory activities.


Content/concepts goals for this activity

The main goal is enhanced skills with identification of carbonate rock components as seen in thin sections.

Higher order thinking skills goals for this activity

Involves analysis of complex visual fields and development of categorization strategies in order to link heterogeneous materials to specific identifications.

Other skills goals for this activity

Involves inspection of complex visual fields.

Description of the activity/assignment

See entry for the Sandstone Tutorial to get information on historical context, the general character of the atlases, suggestions for instructors, and references.

Hardware Requirements
The carbonate tutorial is currently under development and the specific hardware requirements are not yet established.

Program and Functionality
The carbonate tutorial is a web-type interface that can function as a stand-alone server for distribution on CD or DVD. Images are presented as layered .pdf files that feature high-resolution scans of entire thin sections. Typical samples include three layers: plane polarized light, cross-polarized light, and a gridded scale layer. Other image types such as back-scattered electron images, cathodoluminescence, and X-ray maps are included on some individual images.

As with the sandstone tutorial particular features are mapped and connected to information concerning component identification. The same sense of exploration that characterizes the sandstone tutorial will be possible with this new product.

In a significant departure from the approach of the sandstone tutorial, the images are zoomable across a range of approximately 800 percent. This allows both larger-scale rock fabrics and individual allochems and crystals to be observed in the same image and acknowledges the generally coarser-grained nature of limestones as compared to sandstones. Also, because authoring of .pdf files is simpler than programming in Authorware???, the carbonate tutorial will take advantage of community participation in authoring individual samples. Individuals expert in particular aspects of carbonate geology will contribute annotated images of samples that they believe should be part of the collection.

Virtual Thin Sections

High-resolution scans of entire thin sections yield image files that can be considered "virtual thin sections" (Choh and Milliken, 2004). The utility of these files extends beyond their use in the curriculum into applications in research and archiving of collections. High-resolution makes it possible to record the physical attributes of the section with great fidelity, such that it is possible to glean nearly as much information from the digital file as from the specimen itself. It is also important however that much of the value of a specimen or collection of specimen resides in the information, both factual and interpretive, that attaches to the material. It is in this area that virtual thin sections surpass the utility and value of the actual specimen in several respects: information is integral to the image file; information can attach to specific regions of the file; data on one specimen can be easily linked to information on another (for example, for comparison); the specimen and its information can be navigated quickly (e.g., by automated searching); virtual thin sections can be widely duplicated and shared.

The characteristics of virtual thin sections have tremendous utility for linking research with education. Virtual thin sections created and annotated by experts in the context of research collaborations can be duplicated and transferred to educators who can then utilize the "specimens" in the curriculum. Collections collected and annotated by experts over a lifetime of research can be preserved with their information content intact for future generations.

Determining whether students have met the goals

Evaluation is determined by student performance on laboratory tests of identification skills.

More information about assessment tools and techniques.

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