Microstructure and pore content analysis of a permafrost core by X-ray microtomography

Abstract

Summary Characterizing the quantitative properties of multiphase geomaterials such as permafrost is a significant challenge for both engineering and geophysical fields. This paper presents preliminary findings from a project that aims to investigate the microstructure and the changes in pore contents of a natural permafrost drill core from Tuktoyaktuk Coastlands, Canada, as it thaws. The sample was analyzed using X-ray microtomography (μCT). Using high-resolution μCT images (50 µm), we could map the microstructures and quantify the volume of ice, brine, gas, and two types of sediment, as the cores were exposed to a thawing temperature experiment. The images revealed that the sample has an irregular reticulate cryostructure pattern. The phase transition of pore content was observable at different temperatures, with distinct peaks of ice and brine in the vertical profiles. In future studies, additional permafrost cores from the same region will be analyzed using μCT, and the information from the images will be combined with electro-acoustic data collected on the same samples to investigate how different cryostructures respond to thawing and how this affects their electro-elastic properties.