Characteristics of Paleostress Field in the Klodnicki Fault Zone (Upper Silesian Coal Basin) Based on Optical Anisotropy of Coal

摘要

The aim of the present study was an application of coal optical property measurements for analysis of structural development of the Klodnicki fault zone ― one of the main tectonic discontinuities in the Upper Silesian Coal Basin (the USCB). Optical properties of vitrinite depend on physical conditions during coalification; therefore, it is possible to determine the process of coal basin development basing on reflectance anisotropy measurements. Measurements of vitrinite reflectance were carried out on six coal samples. Four of them had been taken near a hanging stope of the Klodnicki fault in coal fields belonging to the Wujek mine and Staszic mine. Two other samples had been taken on opposite slopes of the Krzyzowicki fault in mining area of the Pniowek mine. Vitrinite reflectance measurements were done using a petrological microscope with linearly polarized light source. Maximum and minimum apparent reflectance values (R'_(max) and R'_(min)) were measured. Vitrinite anisotropy was described by Reflectance Indicating Surface (the RIS) which was a geometrical representation of the optical anisotropy tensor. The presented study shows the usefulness of coal reflectance measurements in the analysis of paleostress field existing during the forming of coal basin when coalification process continued.