SEM photo at 250X. Since it is possible to induce fractures during sample preparation, often one cannot be sure whether the fractures observed in thin section are original or artifacts. In this specimen, the backscattered electron image shows a change in composition along the fracture. Although the EDS compositional analysis did not change between lighter an darker matrix, the darker region may be hydrocarbon saturation (thus producing a darker image) or more porous (less mass to backscatter the electrons). Note that in this region only, tiny carbonate rhombs occur.
1000X BEI of alteration region along fracture. The 10 semi-quantitative point analyses indicated that there are small quantities of A1203 with the silica phase. Sphene, pyrite, and feldspar (anorthoclase) were found.
