Dual-energy X-ray computer axial tomography and digital radiography investigation of cores and other objects of geological interest

An X-ray multi-purpose dual-energy computer tomograph has been used to investigate a variety of objects of geological interest such as unconsolidated sediments (sand, silt, clay, mud) and/or metamorphic rock samples. By using an appropriate set of standard materials as well as a proper version of filtered back projection reconstruction algorithms, we have obtained for each studied sample two images, depicting with an error of 2 to 3% densities as well as the effective atomic number. In the case of unconsolidated sediment samples, the computer tomograph has been also used to obtain good quality radiographs, prior to obtaining the tomographic images of the cross-sectional area of interest. Both radiographs and computer axial tomography images had a spatial resolution of 0.4 to 0.5 mm. Digital radiographs as well as tomographic images of unconsolidated sediment samples show with clarity internal features such as grain sizes, laminae thickness and orientation, bioturbations, revoked materials or fragments of wood. Computer tomography analysis of rock samples reveals rheological features in the relationship with metamorphism and deformation, image contrast regarding density and atomic effective number of constituents, as well as significant correlations between physical parameters and internal structures or textures.