3-D Reconstruction

My colleague Ross Moore and I have reconstructed and analysed complexly folded and refolded surfaces using the program Mathematica. We recently published a paper in computers and geosciences (Moore and Johnson, 2001 - see publications) that covers all the work we have done so far, and you can also find an html version by clicking here.

To date we have reconstructed spiral-shaped inclusion trails in garnet porphyroblasts, and oppositely-concave microfolds in and around plagioclase porphyroblasts.

Click on this image for a larger view of spiral-shaped inclusion trails in a garnet porphyroblast from Nepal.

Click on this image for a larger view of oppositely-concave microfolds in and around a plagioclase porphyroblast from Australia.

For the porphyroblast studies, we made serial thin sections through porphyroblasts, traced the inclusion trails and matrix foliations in each section, and used these tracings for our reconstructions; below are two examples.

Reconstruction of the central inclusion surface within the garnet porphyroblast above.

Cutaway view of reconstructed oppositely-concave microfolds in and around the plagioclase porphyroblast above, which is coloured green.

We also made QuickTime movies of the reconstructions. All this material, or appropriate links, can be found in the paper cited above, but if you want to see a spinning central inclusion surface reconstructed from the above garnet porphyroblast, click here. Note - this QuickTime movie is 360K.

We have also used Mathematica to model superposed folds and the many interference patterns that can be found in 2-D sections through them. Below are a couple of examples, but have a look at the preliminary html version of our latest paper (link above) for lots of 3-D refolds, 2-D interference patterns, and movies that serially-section multiply folded rocks.

Click on this image for a larger view of this crescent moon interference pattern - a result of Ramsay Type 2 refolding. From Olary, Australia.

Click on this image for a larger view of this dome and basin interference pattern - a result of Ramsay Type 1 refolding. From the Nepal Himalaya.

In the images below, this first fold form is overprinted by three others in different orientations to form the three basic types defined by Ramsay.

Type 1 refolding. The fold form on the right represents the overprinting, or second fold.

Type 2 refolding. The fold form on the right represents the overprinting, or second fold.

Type 3 refolding. The fold form on the right represents the overprinting, or second fold.