Shape Preferred Orientation (SPO) methodology for oriented hand specimens of rock and outcrops through digital image processing

Abstract

The shape-preferred orientation (SPO) is a technique, which allows the study of the fabric of deformed rocks and understanding its dominant deformational style and partitioning. This work presents SPO results and methodological aspects for one hand specimen of rock and a highresolution composed image of an outcrop through digital image processing. The technique involves imaging of three semi-orthogonal oriented sections for digital processing and subsequent implementation in structural software. The image processing consists of digital separation of a phase of interest, i.e. defining the deformational fabric. The processed images are then implemented in the SPO2003® software for acquisition of sectional ellipses and finally implemented in the Ellipsoid2003® software to obtain the characteristic ellipsoid of deformational fabric. For outcrops, due to the difficulty to finding three appropriate sections for photography, it was only obtained a sectional ellipse, characteristic of the rock fabric based on contrasting deformed quartz segregates in mylonitic schists.