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RESEARCH PRODUCT

Pore-space characterization of an altered tonalite by X-ray computed microtomography and the14C-labeled-polymethylmethacrylate method

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[1] The structure of geological materials strongly affects migration processes that take place in them and are also important in their weathering and alteration processes. Further information of that structure will also be important for many applications that involve geological materials. The emphasis of this study was thus to characterize the pore structure and porosity of altered tonalite by combining different measuring techniques: X-ray tomography, the14C-polymethylmethacrylate method, electron microscopy, and argon pycnometry. Intragranular porosities were determined using chemical staining of rock surfaces. Three-dimensional distributions of minerals and porosities were evaluated with consistent values for the total porosity. Porosity and pore size distributions together with pore connectivities were also determined. Combining the results of different methods, a 3-D porosity map was outlined for one sample. This porosity map enabled us to model, for example, diffusion in a more realistic environment. Scanning electron microscopy was used to identify the minerals and to obtain information on mineral texture and alteration state. The methods introduced here can be applied to many porous materials.