Image Analysis of Petrographic Textures and Fabrics Using Semivariance

Andrew R. H. Swan and Jane A. Garratt
School of Geological Sciences, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey, KT1 2EE, UK

Abstract: Many subjective descriptive terms such as ‘smooth’, ‘coarse’ and ‘anisotropic’ are routinely used to convey properties of textures and fabrics, but these aspects of geological objects are not easily quantifiable. The use of directional semivariograms of image greylevels is assessed for this purpose. These quantify anisotropy of ‘coarseness/fineness’ by using semivariogram ranges, and ‘roughness/smoothness’ by using semivariogram sill values. These can be summarized by ellipses derived from semivariogram ranges and directions. The method will find applications in analysis of rock thin sections as well as analysis of surface texture of grains and microfossils.

Keywords: image analysis • petrographic textures • fabric • semivariance

Mineralogical Magazine; June 1995 v. 59; no. 395; p. 189-196; DOI: 10.1180/minmag.1995.059.395.03
© 1995, The Mineralogical Society
Mineralogical Society (