PDF indexing

Planar deformation features (PDFs) in quartz grains are the most commonly used diagnostic features of hypervelocity impact structures. PDFs are straight, parallel sets of planes of amorphous material that are less than 2 µm wide and spaced 2-10 µm apart. Specific combinations of PDF orientations provide information on the peak shock pressure recorded by samples, within the range of ~5 to 35 GPa.

The determination of PDF orientations is usually done using a universal-stage (U-stage)-equipped petrographic microscope, followed by indexing measurements to crystallographic orientations in relation to the c-axis. Currently, indexing of PDFs is done manually using a Wulff net and a stereonet and following a strict procedure, which is both time consuming and error-prone. Because of limitations of the manual indexing method, only information about polar angles and Miller-Bravais indices of PDFs were recorded and used in previous studies. The angular relationships between PDF sets were in most cases ignored. Here, we present a web-based program for indexing PDFs that also allows for analysis of azimuthal angles between PDFs in a given quartz grain. The study of combinations of PDF orientations can be useful for a better understanding of impact processes. Our program is available from: http://lithosphere.univie.ac.at/impactresearch/. The source code (i.e., implementation in Java programming language) will be made available. Read more...

Description of the program

Download a sample input file and use it to test the program.