Nondestructive high-resolution visualization and measurement of anisotropic effective porosity in complex lithologies using high-resolution X-ray computed tomography

New methods are presented that allow high-resolution X-ray computed tomography (HRXCT) to be utilized for imaging and measuring the effective porosity field of mineralogically complex specimens at resolutions in the 5-100 μm range. These methods extend previous established approaches by allowing sample displacement between successive imaging runs and eliminating the need for a highly-attenuating tracer. A highly detailed map of partial porosity can be generated by scanning a sample in a dry state and infiltrated by distilled water, and performing a three-dimensional alignment of the two data sets. This map can then be used to obtain a number of quantitative analyses, such as the frequency distribution of partial porosity and directional analysis to infer flow anisotropy. It can also be used for petrographic study of the relationship of porosity to evolving mineralogy in a dynamic system. These methods are demonstrated on a series of altered volcanic rocks from a deep-sea hydrothermal field.